RESEARCH LABORATORIES ANNUAL REPORT

JANUARY — DECEMBER It**

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i»r«»J Atomic Energy C»« l»U« i»B

A V A l l A • I L1 TV

Itroti Atomic Energy Commission raporis and bftHtogfophiw may be obtofnccJ on application to :

TECHMKAl IMfOtMATIOM DEPARTMENT ISIAEl ATOWC ENERGY COMMISSION

r . 0 . I . ( 7 1 2 0 - l TRMiVIV, ISHAI l

I A - 1 2 1 8

RESEARCH LABORATORIES ANNUAL REPORT

January-December 1969

Israel Atomic Energy Commission

[

C O N T E N T S Page

NEUTRON AND REACTOR PHYSICS l

Solving Reactor Dynamic Equations by a Hybrid Method... 1 A Program for Solving the Multigroup Space-Time Dependent

Diffusion Equation With Temperature Feedback 4 A Fast Method for Setting the Initial Conditions of an Analog Hybrid Computer 6

The Effect of Errors in the Delayed Neutron Data on Fast Reactor Static and Dynamic Calculations a

The Solution of the One-Dimensional, Hultlzone, Multigroup Diffusion Equation using the Lie Series Method .. 10

The Solution of the Two-Dimensional, Hultizone, Multigroup Diffusion Equation Using the Lie Series Method 10

Integral Transport Theory in Spherical Geometry. ]1 PL/K Method - Applications 12 Fluctuation Factors for the Theoretical Evaluation of Average Neutron Cross Sections of Fissile Nuclei, in the Unresolved Resonance Region 12

Nuclear Data for Pu-240,241,242 U Fast Breeder Reactors for Desalination 14 Power and Water. Feasibility Studies 15

NUCLEAR PHYSICS Xj

Dynamic Investigation or the Core Excitation Model 19 Calculation of Energy Levels in the 16 £ A i 21 Region. i<> Oelbruck Scattering of 9MeV Gamma Rays 20 Precise Measurements of Attenuation Coefficients of

Gamma Rays in the 7 MeV Region 21 Parity Determination of Resonant Levels Excited by Tita­

nium Capture Gamma Rays 22 Fluctuations of Partial Radiative Widths in Nuclei Exci­

ted by (Y,Y') Reactions...., 23 Measurement of Nuclear Level Widths in the 6-9 MeV Energy

Region Using Resonance Scattering of Ml Gamma Rays 24 Use of a New High Resolution Genu Monochromator 25 Gamma Ray Intensity Anomaly in the (YIY 1) Reaction 26 Study of the Energy Levels of Z03 T i Using the (Y,Y')

Reaction i. 28 Study of Level Structure of 5 0Ti Using the *9li (n,Y)

Reaction 23 The Level Structure of 5 i T i Studied by the 50 ri (T),Y) Reaction 29

Study of Energy Levels of Using Nuclear Photo-excitation * • 2 9

Use of the (Y.Y) Reaction for Studying the Energy Levels of 75AS 31

Study of the Energy Levels of " 2 C d Using Kucleer Photoexcltation 32

Study of the Energy Levels of " 9 L * Using Nuclear Photoaxcltation...,,«.... 33

The Level Scheae of 1 3 9ta,, Studied by Photoexclration With Theraal Neutron,Capture teams Kays 34

The Level Schsiaa of l w P r Studied by Photoexcltation With Neutron Capture Gaama lays . 35

SOLID SIATE PHYSICS AW HSTALHISOY 37

Have taction f o r Sol id %c . . . . 39 The Energy Gap Law lor Kadiationlese Trannitions In

Lug* HolKule* 3 9

Ceeerallaed (eduction Faccore for the Jahn-Tallar Effect oa a Doublet 40

Optical Phoooa* of. S*«ll Cry*t»l* *0 Meaaetoelectrlc Efface in Doubly Fol*ri»«d System*... 41 S l » Effect* oo Fla«*on-Phouon Had** in Polar Seel- _

coedMctore. . . . . . . . . . . . . . . . . . • . • • 42 lb* Solution of the oDltsaann Transport Equation for

a Single Phonoa Mote In Solida, With Hoaentua Con-eerrlag Colllelone 42

Theory of the Interaction Between an Impurity and the Boat La t t i ce 43

lata Coaataata of Optical Emission in Ruby 44 Zero-Phono* I r a u l t i o a at tha trceutar in Kaf 45 ESI Spectra of Ik Ion* in Simla Cryatala of HgO 46 E S E o f l r * 4 , in HjO.. . . . 47 Ihernoluartnoocoaf.a and Ear in Boron Hitrld*>.>.. 47 Moeabeuer Study of Hacrli-Isolstsa lodin* Compound*.. 47 Hoaabauar Study of Iodine-Fluorine Coapound* 48 High Teaper*tura Pnaa* Tranaition in ET^POA Type

Cryacala 49 Mossbauor Effect Study of tba Ferroelectric Phaaa

Iranaltion of XH PO* Type Cryatala 50 Study of tha Ferroelectric Behaviour of Hydrogen Bon-

dad Ferroelectric* by neutron Scattering SI Kechanleai Landing to Farroalactrlcity Induced in Csn-

troeyaaetric Crystal* by AAtlferroewgnetlc Tranal-t loa t 52

Landau'* Theory of Second Order Phaaa Tranaition*.. . . 52 Balicolaal Magnetic Structur* of « Lln*ar Atonic .Chain 53 Koaabauar Effect Studies of Intametal l lc Irca-Antiaony

C o B p o a a a e . . . . - . . . . . * • * * • • • . • • • • • • . . . • • 53 Hoaekauar Effect in Ferrltee 54 Hagnetic Field* at Nuclei of Magnetic loee in Iroa end

F i n i t e * Studied by I m a t l Scattering of Nuclear. Caana laya 54

Hoeabeuer Effect Studiea of the Cubic Lave* Accinide-Iro* Intsraatall ic Compounds . 55

Charge State* of ftp sacoi l Atoa* Following Alpha Decay 55 SubUttic* Magnetisation in YbPeO, and VFe03 e* Obtain­

ed by Meutron Diffraction and I t s Halation to the Hyperflne Tleld 55

Neutron Diffraction Mseeureaent* of Powder ThFeO, 56 Xeutron Diffraction Study of Powder HMnCl, 56 neutron Diffraction Study of PolycrystelllSa Samples

of tbjknCl, end C*,HaCl. 57 Allowed asutroa aeflecCions fro* Magnetic Lat t i ce s . . . 58 Fmpsrstlsa aad Cryatal Structure of to** Compound*

of tea Type A j £ 59 Preparation aad Crystal Structure of TlanCl,, TIFeCli,

TICoClj and TINiClj 60 Low Teapmrauirs Elasticity, aad Hiaaafooltetlcity of

Oyspreaiaa Single Crystals 60 Elastic aad Kagaatoelaatic Propertia* of Terkiua,

adlsd.ua aad Irklua Single Crystal* at Low Teaeere-taree 41

Ill gage

SOLID STATE PHYSICS AND METALLURGY ( c o n e d . )

E l a s t i c Moduli and Ultrasonic Attenuation in Thulium, Ytterbium, and Lutetium from 4.2 to 30Q'K 61

NMR of Al l a TiAl and TiAlH Alloy• 62 Spin Lat t i ce Relaxation time of Protons In Uranium

Hydride . . . . . . . 6 2 NHR Study of Hydrogen Diffusion in the Three Phase* of

the Titanium-Hydrogen System r . . . 63 A Method for Precise determination of HMR Line Gentera

Using Analog Fourier Transform* 64 Diffusion of Copper and Zinc in Praseodymium 66 Diffusion of Cobalt in Beta-Uranium.... , 67 Oxygen Self Diffusion In UO 67 Kinetics and Mechanism of t&e Age-Hardening Process

in Aluminium Alloys . . . 68 Research on LLSi, 69 The Effect of Hydrogen on Cracking in Irradiated

Uranium 70 Composite Materials by Chemical Plating 71

PURE AND APPLIED MATHEMATICS 75

On Algebras Connected t o L i e and A s s o c i a t i v e Algebra* 77 The Power o f a Matrix and the General ized Lucaa

Polymonials 7fl Cayley-Hamilton I d e n t i t i e s f o r Matrices With Non-As­

s o c i a t i v e Elements 73 On the Korovkln Summability Operator for Double

Fourier S e r i e s 79 Construct ion of the Fe jer Kernel from a Maximum

Principle v , SO An Expansion Theorem for Products o f Generalized

Herraite-Gatissian Functions 81 Molecular I n t e g r a l s Over Generalized Hermite-Gaussiaa

Functions SI Molecular I n t e g r a l s Over Gaussian Functions 81 Phys ica l Rea l i za t ion of Non-Compact Dynamical Symme­

tries ^ ei A System With Infinitely Degenerate Sound States . . . 82 On the Use Of Second Quantization for the Calcula­

tion of Two-Centre Harmonic Oscillator Integrals. £2 A Simple Solution of the Linear Potential Problem.. 82 Analysis of Variance by the Range Method 82

HIGH F'ERCY AND NUCLEAR CHEMISTRY 85 Derivat ion of the Average Decomposition Prot i b l l i t y

o£ Hot Molecules During Moderation 87 Moderation Preceases of Hot Atoms l a the Gaseous

Phass 88 The'Influence of Energy on Hot R e a c t i o n s . . . . . . . * . . . On the Problematic! of the B i l l i a r d Ba l l Modal f o r . 90

High-Energy Displacement Reactions in the Gaseous Phas* 91

The Eff icacy of Various Scavengers i n the Study o f Hot Chlorine Reactions 92

Delayed Neutrons in F i s s i o n . 92 A Ssmi-Rmpirical Treatment o f Xeutron Emission Proba­

b i l i t i e s from Delayed: Neutron P r e c u r s o r s * . . . 92 Determination of Independent F i s s i o n YieMa o f Shoct -

Lived Halogens in Thermal F i s s i o n of * 3 5 U 93

£ut HICH EHERCY AND NUCLEAE, CHEMISTRY ( c o n t d . )

Separation of Fission Produced Iodine by Surface loalaatlon •

On-Ll*e Bxperimeate on Short-Llvod Kara Caa Fiaeion Products.

94

96 Prlnsry Maaa Distribution of Kr laotopaa Formed In tha Thermal Flaaloa 9 6

Bnpid Separation of Antimony Iaotopca from Z 3 5 U Fiaalon Products "

SOUS Isotope Separotor: Auxiliary Instrumentation and Operating Conditions " e

The Ssllard-Chalmers Enaction on Callium Phthalocya-alae in a High neutron Flux 100

A Computer Program for Activation Aualyala uith very Short-lived Euclidee 101

Coaparisoo of Several Hethods for the Correction of Dead-Time Effects in Gamma-Kay Spectrometry Meas­urements 101

X-Bay Fluorescence Determination of Uranium Solutions alth a Lithium Drifted Silicon Detector 102

neutron Activation Analyaia of Uranium by Multiple Gaame Kay Batio Determination !04

Lithium Iaotoplc Analysis by Neutron Activation and Simultaneous Keeaurement of Li and 1 7 H 104

Determination of Trace Elements in Biological Mace-rlala by Neutron Activation and X-Ray Spectrometry. 1^°

Xondeatructive Activetion Analysis of Gallium.:'. 106 neutron Activation Analyaia by a Combined Cepture and

Decay Gamma Spectrum Method 107 KA9IATZ0N CHEHISTftY 109

i mediation Induced Cheln Decomposition of Tetre-amd Pemtaehloroethane in tyclohexana Solutiona..... H I

Determination of Arrhenius Parameters in the Gammn Indueed>Pree Radical Compensation Enaction Between Alkaaes'and Chloroethylenes 112

negative Ion Formation in the Eediolysls of Arylchlo-rides in Cyclohexana Solution 112

Kinetics and Mechanism of Radiation Induced Syntheaia of Substituted Chlsroolefins 113

Isotoplc Exchanga Induced by Excitation of tha Iodlne-lodobeaseae Charge Transfer Complex 114

Effect of Uganda on Inactivity of Hetal Cations To­wards tha Bydrated Electron. Part 2. Effect of Gly­cine Ethyleaadlamlne and Kltrilotrlacatlc Acid.... U S

•eduction of Cobalt (III) Complexes by Monovalent Zinc, Cadmlsm amd lickal low 1* Aqueous Solutiona. 115

Tha Effect of Tlgonds on the Chemical Propertias of Monovalent Ceamlmm low 115

Tha Pnlae ladlolvsla of Aeneous Solutlona of Lantha-aids* Eu(lll), YbCllli, Sn(lll) and Tb(lll) 116

Effect at Positively Charmed lone on tha Hydrogen Y U M la the ladlelyals of Aqueous Solutions 117

PHYSICAL AND INuRGAHIC CHEMISIBY 119 Phase Semes Theory in Chemical Kinetics. 121

V

PHYSICAL AND INORGANIC CHEMISTRY (contd.) Negative Ion - Neutral Molecule Interactions by

Pulsed Mcrhods 121 Kinetics of Reversible-Consecutive Reactions. A Com­

plete Mathematical Solution 173 Molar Volumes ol Electrolytes and Ionic Radii 124 Apparent Molal Volumes in Mixed Salt Solutions:III.

The Reciprocal Aqueous System LiCl-NaNQ. 125 Determination of Hater Vapor Pressure Levering of

Dilute Electrolyte'and Non-Electrolyte Solutions in the Range 0.02-0.1 Molal 126

Relative Stabilization of the Higher Oxidation States of Americiua 127

Electrocatalytic Oxidation of Amines on Platinum Electrodes. Part II. Oxidation of Copper Ethyle-nediamine.., . 1-8

Electrecatalytfc Oxidation of Amines on Platinum Electrodes. Part III. Oxidation of Nickel Ethyle-nediamine * 129

The Polarographic Reduction of Chlorate Catalyzed by Molybdenum-Tungsten Mixtures ...... 129

The Eleccrodeposltion of Indium 130 The Microstrueture of Thin Electrodeposited Cobalt

and Cobalt-Phosphorus Films 131 Surface Treatment of Aluminium 2S 131 A New Electrolyte for the Anodic Dissolution of Re­

fractory Metals.. * . 131 Working of Refractory Magnesia Bodies 132 Systematic Study of the Nature of Electropierclng and

Cutting of Metals 133 Phenomena of Corrosion and Capacitance 133 The Double Layer, VI, Electrical Aspects.. 134 Quantitative Gas Chromatographic Analysis of Gases

Evolved in the Electrolysis of Nitric A d d 135 A Method for Sampling Gases Evolved During Elactro-

lysi - 135 Thermodynamic Properties of Associated Solutions of

the Type: A+B+AB. and A+B+AB.+Ar 135 Mutual Solubi l i t ies of Diphenyl Methyl Phosphate and

Some Aliphatic Hydrocarbons 138 Gas Chromatographic Studies of Solvent Extraction

Systems. I I . Diphenyl Methyl P h o s p h a t e . . . . . . . . . . . . 139

Extraction of H.C1 and H2SO4 by Solutions of Trlbutyl Phosphate In Carbon Tetrachloride! Benzene and Chloroform 140

Separation of Alkali and Alkaline Earth baits by Sol­vent Extraction 141

Studies on Amine Salt Solutions at High Temperatures by Distribution and Gas Chromatographic Methods,,, 142

Osmometric Measurements of 1-Chloronaphthalane Solu­tions of Various Amine Sslta at 100*C 1*3

Mixed Chlorlde-Blaulfata Complexes of Ga l l ium. . . . . . . 144 Ketone Extraction of Mixed Chlorlde-Sisulfate Com­

plexes of Aluainiuri and I n d i u m . . . . . . . . . . . . . . . . . . . . . 145 Anion Exchange of Metal Complexes. XVII. The Selec­

tive' Swelling of the Exchanger In Mixed Aquaous-; Organic Solvents • 146

Illft PHYSICAL AND INORGANIC CHEMISTRY ( c o n t d . )

I b i t M l Regenerat ion o f l o o E x c h a n g e " 146 S o l u b i l i t y o f Calcium S u l f i t e In Sea Water 147 Draayl N i t r a t e - Organic Phosphate Exchange R e a c t i o n 148 Transport of Uraayl N i t r a t e Through S o l v e n t - Heabra-

aaa 148 Diffusion Coefficients of Uranyi Nitrate in Phosphate

Ester Solvent-Membranes 14° Purification and Separation of Plutonlum-238 and

Waataat—-237 150 Preparation and Properties of Uranium Dioxide 151 Recovery of Uranium as a By-Product of Pboephoric

Add Production 152 Production of Metal Fovr^ra by Reduction of Metal

Sal ts i a Sprays 153 A Labaratory Apparatus for Studying; the Thermal Decoat-

poeitioa of Solutions of Salts in Falling Droplets. 153 Production of Pur* Mitel Oxide* by Theraal Diasoci.fi-

tioa of Tbeir Salts in Sprays. Preparation of AljO, Standard Reference Materiel 155

SPECTROSCOPy AMD SPECTHOCHEMICAL ANALYSIS 157

Good L-S Coupling i n S i n g l y I o n i z e d 111 and Cu 159 Hew *ff 8 ( 7 F ) 6 e L e v e l s o f S i n g l y I o n i z e d Gadolinium

(Gd I I ) . . 1 6 0 "Cathode legion" Method for the Spectrocheaical Deter­mination of Impurities in Rare Earth Matrices...... 160

Concentration and Velocity of Uranium Particles in a' DC Arc Flasaa 161

Indirect Spcctrochcaical Determination of Minute Im­purities In "Pure" and "High Purity" Metallic Zinc. Irl

Spectrochcmicel Determination of Soaa Trace Elements ia U S Standard fcficenc* Materials: Zinc Metal 683 and Alfalfa...;. 162

Spectrocheslcal Analysis of Jar Handles from. Archaeo­logical Excavations v ; 162' ~

GEOCHEMISTRY 165 2 3 4 U / Z 3 8 U gatio in the Red See 167 Absolute Dating of Some Marine Terraces on the Islend of Tiran * 167

Compositional Changes In Sea Hater in Contact with Rocks 168

The Haaaat Cader, Huqeib and Gofra Springs 169 Pyroclastlc Cones and Explosion Cratera In the Golan. 170 neutron Flux Estimates on the Moon...,.; 171

FOOD IRRADIATION AND APPLICATIONS OF TRACER TECHNIQUES 173 Attempts to Reduce Postlrradlation Damage to the Peel

of Stored* Field - Infected Citrus Fruit 175 Combined Heat, Radiation and Dlphanyl Treatment* to

Reduce lot in Citrus Fruit Inoculated with Paolcil-lium Itelicum and FenicilUua Digitatua 176

Effects of Gamma Radiation on Ethylene Production, Phenylalanine Aanonia-Lyase Activity and Protein Synthesis in Grapefruit Feal * ' 177

VII

£2X1 FOOD IRRADIATION AND APPLICATIONS OP TRACER TEOCUQU2S (contd.)

Development of Discoloration of the Sprout Bud during Postirradiation Storage of Onions 1.78

Storage Experiments on Irradiated Onions 179 Chemical Analyses of Stored. Irradiated Onions 160 Effect of Irradiation on Chemical Composition of

Stored Potatoes 181 Storage Test of Winter Harvested Potato Crop 183 Retardation of the Post Harvest Ripening of Avocado Pears 183

Prolonging the Shelf life of Bread 184 Determination of the Dilution of a Gas Discharged in

a Specially Ventilated Atmosphere 185 The Use of Radioisotope Tracers In the Study of the

Dispersion of Sewage and Xnactivatlon of Bacteria Discharged into Coastal Waters 185

Concentration Dynamics In a Lake with a Water Current Flowing Through It 186

The Use of Radioisotopes for Measuring the Sediment Movement in a Small Wadi 187

RADI0BI0L0CY AND MEDICINE 139 Effects of Dose and Temperature on the Formation of Photoproducts from UV-Irradlated DNA, .. ., 191

Photoproducts of Frozen Thymine Solutions Irradiated by UV Light 192

The Effects of Ionizing Radiation on the Emergence of Adult C. Maculatus from Infested Grains.. 193

Comparison of Relative Uptake of Gamma Emitting Ra­dionuclides by Some Local Aquatic Plants 1?4

Gastrointestinal Absorption of - Ce in Suckling Mice 195

Modifying the Survival of Irradiated Rats by Pneumo­thorax 197

2-Substituted Selenazolidines as Potential Radlopro-tection Agents v 198

Growth Inh ib i t ing Ef fec t s of Cytotoxic Agents on Human Tumor and Tumor-Bearing Normal Tissue i n -Vi tro: C l i n i c a l Application 199

Use of 1 3 1 I - L a b e l l e d Rose Bengal for D i f f e r e n t i a l Diagnosis of Jaundice , * • 200

Use of Whole-Body Counting i n Anemia With Iron Defic iency 200

Bloodstream Background Subtraction i n Renography. . . . 201 A Case of Insoluble Natural Uranium Contamination, a

Two-Year Follow-Up Study 202 A S t a t i s t i c a l Survey of Potassium Content i n the

Human Body, by Whole-Body C o u n t i n g . • • • * > . . . . . . . . . . £03

HEALTH PHYSICS 205 Radiation Safety Whole Body Counter 207 Long-Lived Radioactive Fal lout i n I s r a e l . . . . ' . 207 1 3 7 C s and ^ S r Levels i n Fbod . . . i 20« Inf luence of Flocculants on the Decantation of Ttew-

t r a l l s s d Radioactive Wastes 209 Use of Adsorbents i n Liquid Wests D i s p o s a l . . . 209 Incorporation of Low Level Radioactive Waste Concen­

t r a t e s In Concrete Mixtures . . 210

VIII

ItM. aUCUAl SUEI! 211

A Staple Method for tepid latlaatloa of Dlapareloa. 213 • u r i Evaluation at the 1MCM 213 Meteorological Prediction far Air Pollution Evalua­

tion; C M l l t a a in nanusl Frequency Distribution of Winds In I i r i i l 214

nslsoet of Pollutant* to tntt Atnolphere f ran Power Plants: Ara Higher Stack* Always Desirable? 215

Talaad Siting of Muclssr Power Enactors in Zaraal.. 216 underground Locatioa of Nuclear Xaactora In Iaraal. 217 nediacion "Actios Levels" for Different Population

Cmaps 218 Addltivlty of Effects of External and Internal

Irradiation Doaea 219 iKSTUMsranoif AID IT-HODS 221

HEIJuY Isotope Separator 223 Cylindrical mrror Analyser With Surface Entrance

and Exit Slots . I . Nonrelstivistlc Part 226 Cyllndrlcsl Mirror Analyser With Surface Entrance

and Exit Slots . I I . Kelatlviatic Part 226 Ion Bean Stabilizer for Theraal Ionization Sourcea

of Haas Spectronecera 227 A Stabilized Iberaal Ion Source for Maaa Spectro­

metry 228 Haas Hater 229 Progracaed Pulse Generator. . v . . . . . . 230 2-30Hc/s, SOW IMS Pulsed MW Iranaadtter 231 Diaital Stabilizer and Pulacr 231 High Efficiency Integrated Circuit Power Supply*... 233 Digital Integrated Circuit Taster 234 Hoaabauer Electroaechsnlcal Drivs Using an LVayn... 234 A Plaeh Photolysis Htaauring Systan 236 Teaperature Frograanere 23? Level Detector for Liquid Nitrogen 239 Inexpensive. AcccTate Tenparature Control for Bathe. 239 An ttficiency Independent Method in Gaana Kay Spec­

troscopy 240 A Note on the Walford-Douet Method for Rapid Calibra­

tion of Geraeniiai SpectroMtara. . . . . . 243 Abcoluta Cslibraiion of leta-Cssae Sourcea 240 A Saaleoaductor Sandwich Detector for the Slaulta-

aeavs and Independent Counting of Hlxad Alpha-t s ta aaaplas . . . . 241

Pus* far Cerroslva Cases • 242 Oxide furnace 243 Ssalography of Prasaure Seals 244 A Consistent Unit for the Specific Leak lata of Seals 245 The Leak lata Vs. Tightening force in Metallic

O-liags 247 PnOCOCnON Or UHOISOTOPES AND LAUUID COMPOUNDS 251

iMtepic Consosltloa of Ioaina-131 Solutions 253 leparatl—,.*« Carrler-Prae Pkeeaaorus-32 fron Irra­

diated Elsaaetary Sulphur by Taeradc Osieat len. . . . 254 Past Iktbsd for Sasarstlea of Plaerlag-U . 256 Prodactlea ef Ttterbitst-IM Mr* Coaplax 257 Method for Eacoverlng enriched Tia-112 (rsa Eitkana-

tad Iadlan-lUa Csnaratsra 257

IX

Page

INFORMATION EXOIANGE AND RETRIEVAL 2 5 9

Analysis of a Literature Search on Ge-Ll Detectors Conducted by the Euraton Nuclear Documentation Systsa 261

Audiovisual Coewmlcatlon Techniques In Scientific Information DlssealQatloo. 262

NEUTRON AND REACTOR PHYSICS

The following short sucaarles illustrate sane aspects of the work done In the field of neutron and reactor physics during the period of the present report. The topics treated include new and continued work on several problems in East reactor physics and thermal reactor physics. Aeong these are the possible use of Lie series methods in reactor physics, the use of hybrid coraf-uters for reactor dynamics calculations, tiie effects of errors in delayed neutron data on fast reactor statics and dynamics, several transport theory problems, com­putation and evaluation of nuclear data, and the use of fast reactors for desalination.

SOLVING REACTOR DYNAMIC EQUATIONS BV A HYBRID METHOD:

D. Sophier and S. Y'tftah.

Development of the "HVBSKOV" prosra» f « solving ctactor d y a d i c ' equations by hybrid analog and dig i ta l computation has baen continued. The "pyramid1* method developed In Ref.l was fully applied to the solution of the space-time dependent diffusion equation. Many time saving ioprova^ meats were introduced into the HY3SII0V code according to the reece=ien-datloas in Chapter 8 of Baf . l .

«: *o

I TO

i JO

40

10

to

•o

0 WO 200 MO 400 500 «0O Z(tml—•>

Fig. 1 Total power distr ibution at t * 0.04 sec after a perturbation in £ a

has been inserted a t intervals 15 - 17. The curves are the result af 23 i t e ra t ions . I t is seen that convergence i s obtained a t the 19th i te ra t ion

The resul ts obtained for a bare homogeneous fast oxide reactor are presented In Figs. 1 and 2r The reactor was perturbed by a 25 decrease in £ at intervals 16 and 17, and the evolution of the power was followed during a period of 0.24 sec. Figure I shows the power d i s t r i ­bution at t " 0.04 sec after, the perturbation, as obtained Etc* 23 i t e ra t ions . The solution vaa obtained by integrating region after region i s « s e r i a l aethod. I t ia seen that 19 i terat ions were required un t i l convergence was obtained. Figure 2 shows the results for the •«•* problem solved by the fully developed "pyramid" aethod. I t is seen that

Miasm 2

Fig. 1 The transient occurring in' a Cast iPuOl/UO^ reactor following reduction of the flop of, sodlua to -ee ro ln the- l e f t core outer region. In A and B the behaviour of two of the four group fluxes i s shown as a function of space fot various time' in tervals . In C the mean fluxes of the four groups are. given as a function of-time. D shows the spat ia l distr ibution of the fuel temperature. .E shows the change of power aa' a-functlon o'f t i n t , and F the tine behaviour of the

. -. fu«l and,coolant tenperaturei ,

- « - •

tha t i n t applculnalliia t* th* tibaa daaa»d«nt boundary «alu*a at t - 0.0* i«c i s aula* clns* to til* asset raault and only 2-4 iteration* wi.\l b* aaraeaary for th* solution to oonusrge to i t s f inal raluu.

Tko solution* ohtsluad o n In atreaaant with thoa* obtalnad by a pur* dig i ta l cod* (eea next abstract), but * aubetantlal cost reduction 1* acklavad by ualag MtMUOf.

Total powr distribution as obtained by using th* "pyramid" sathod. Iks points In aha dre lasshos th* raluoa obtsln*d fro* ths f i r s t approxlamtlv* solution on til* boundarl«s of th* rftglone, as conpar*d

with til* cosvargad solution l*f*r*nc*: 1. SAHIB., D. and TlrUH, s . , IA-119I; ae* also Annual Itaport IA-1190

<1»W) p.5

A PROGRAM FOR SOLVING THE MULTIGROUP SPACE-TIME DEPENDENT DIFFUSION EQUATION WITH TEMPERATURE FEEDBACK^: D. Saphisr and S. Yiftah.

A digital eouputar prograa, "SBOViT", for solYing ths spsoa-. Uas dependant diffusion aquation with taaperatura feedback has been s s t up for th* ralLCO IKA.1S1C E-2000 coapuur. lb* program Is v r l t u n In IORT11*-!! and aay b* run, with saner chaugas, on oth*r coaputus a* wall .

lb* diffusion aquation Is solTsd for a slab raactor with a s i r l x i of * l * n n rations, on* hundred aeehpolnts, four eoargy (roups

end aa to s i x delayed MUttoo groups. Thn maximum nuabar of isotopes foe which mixtures In the cod* may b« prepared Is can.

Iba mean valuta of f u t l and coolant temperature at each aeahpolnt a n calculated from th* power production distribution in the reactor. The Influence o£ teaperature and density change* (Dopplcr and sodium effects) on tha dynamic* of tha raactor are taken into account via the P*T*I>£ end shielding factors which cause the cross sections to change with temperature and density.

She program, can he used to sinulate various incidents and pertur­bations in fast reactor systems, such as control rod withdrawal, blocking of a coolant channel, reduction of the coolant i n l e t temperature, e t c . "Eie flue poyer, delayed neutron precursor concentration, fuel and coolant teoperftures as a function of space and tine are displayed by the Calcomp Plotter, as shown by a typical example reproduced in part in ?ig. 1.

Eeferance: 1. SAEHZEa, D.» U.Sc. Thesis (Appendix A), Technion - Israel Inst i tute

of Technology (1963)

A FAST METHOD FOR SETTING THE INITIAL CONDITIONS OF AN ANALOG HYBRID COMPUTER: D. Saphiar.

Hfaen integration 1* performed with an analog computer, the i n i t i a l conditions must be supplied to the integrators. Usually th is la done with the aid of a potentiometer whose higher tap i s connected

. to a standard voltage source. With servo-set potentiometers 3 seconds art required for a s ingle set t ing . Thus in a problem with 50 integra­tors, for example, 150 seconds w i l l be necessary for the I .C. set t ing . If the solution of the problem requires an i terat ive procedure, 2.5 minutes are los t during each cycle .

Daring the preparation of tha HTB5B0V program C' a fast method requiring only a fraction of tha above time was developed* This method ewes DAC (Dlgital-to-emelog Converter) channels instead of potentiometers.

The method requires logic switching circuitry, as shown in Fig. 1. l a this example *•• Integrators are set by 8 DAC channels In a sequential meaner - 8 at a time. The logic cycle Is started by a puis* In CL-1 (Control Lime 1) ufcica starts the timer. Each timer haa tour reglaters -> ,1 ,C ,D - capable of counting up to a preset number (maximum 99). The output of• the 1 register in which counting occurs la' "1" - in the others i t i s "0".

Upon appearance of a pulse in the "A" register output, it in fed into a differentiator, which releases a 1 uacc vide pulse. Thin pulse ia fed through an OR gate to o BCD downcounter. A logic network connected to the various outputs of the BCD perfonas the appropriate switching of the Integrators and connects thea to the ADC chancels. The BCD counter Is started by a pulse through CL-0 which is fed through another differentiator. This is necessary because the usual reset node of the timers is in the "A" position.

MITtAL CCM3IT10N Si

»6J0 t430 *2J0 A«0 - — A600 - — A4Q0 *!00

AMI A 431 -— •111 AMI - — A50I -—• 9401 — AZOI

A6«0 — A440 A2«0 - — A040 A6:0 - — A410 A2t0

B f- B^ B^ I »» > ' .?, ' ' ,«,'

«sao -— AG*. I

4 4 J O — — • 4 3

azso A 2 S i — A S 2 D - — 1 A S S l .— A 4 2 D ' • 4 3 ' IZZO

<5?> Iter > l c J .c [

Fig. i Logic circuit providing ssqucntisl connection*

for setting th* initial conditions

- a -

After A coumta, the timer passes to the 1 regiater, whoM output I s thee M t to **1N. Tlilfl output la us«l aa a starting pulee feel taxouma SL-0 for transferring the I . e . valuea from the DAC registers to the switched imtegratore. The A period (10 maac) 1* smesesery ta assure that th* ewitching of tba i.. fcegratora haa bian commleted.

The I . e . ' a ace eat during tba *+C*D period, vhlch la long sanrngh to act a l l the eapacitore to their proper values. Thia period may be adjueted op to a B " < — of 3000 maac. At the end of the Betting period a carry over pulse from CO of the BCD Indicates through 5L-1 that the sett ing procedure i s over*

The tota l I .C. sett ing time by the above procedure ia 6 see i f 1 uF capacitors are used (or ^ 0.6 sec for 0.1 vT capacitors) which la only 41 (or 0.4t> of the usual set t ing t ine .

gafarence: 1. SAPHTEa, D. ard TfUTAB, S . , IA-1191 (1969)

THE EFFECT OF ERRORS IN THE DELAYED NEUTRON DATA ON FAST REACTOR STATIC AND DYNAMIC CALCULATIONS: D. Saphier and J. Yiftah.

Tie affect of the errors in tine presently available delayed neutron data on various calculations and ocasuranenta in reactor physics were analyzed. Discrepancies between calculated and oeaoured react iv i t ies on tba one hand* and between calculaud values using different data seta on the ocasr, are a wel l Unown fact* . The discrepancies are particularly large ulian measurements are nad* by t :ia heated sample Insertion or material replacement methods. While various integral cr l t i ca l i ty calculations differ by 2 - k%, the differences between reactivity mcaeuraoenta and calculation are in the ranee of +10 to 30-, wMcli ia quite large.

jjrom tba calculations performed (see Table 1) i t appears that up to one tnird of the above discrepanciaa may be tba result of the error 1m tba b s i c delayed neutron oats, l'rom tita dynamic cUcula-tiona (sea Tig. 1) i t ia clear tnac wrong aasuaptlona concarning the delayed neutron vpectra may cause large errors La predicting the dynamic behaviour of fast systems. I t ia concluded that ttiuxm U an urgent need for exact delayed neutron data in order to Improve calculations in faat systems.

Prooable error I D the reac t iv i ty , to . calculated fico period measurements uainfi delayed neutron .data given by .-tccpinlw

System T(sec) to CO "1 .<% «> toTi a (=)

Ifcta! 2 3 5 u 1

10 100

3.03 3.23 3.40

o.eo 2.92 1.52

1.7 1.7 1.7

3.53 3.31 4.16

Hatal 2 3 9 P u 1

10 100

2.33 2.13 1.39

0.41 0.62 9.87

2.1 2.1 2.1

3.17 3.20 2.i6

Oxide 80Z H s s . In " i P u 20; H s s . In °U

1 10

100

2.46 2.28 1.36

0.44 3.69 0.90

9.0 9.0 9.0

1

9.34 ' . .31 9.26

fip • £ap a . + EAp, ' where a. • r e l a t ive delayea aeucron fraction, \±m delayed precursor dis integrat ion constant, y± - e f fec t lv i ty of the i c h delayed neutron f rac t ion .

i 96 , 290 . 901 1096 Z(em)

•'-'"'•'•'• " • J ' - ' - • : ' : j - • • - - • • ° ' K g , 1

Tranaie'nt reBponM "of large fast reactor 2 sac, after inserting a local perturbation, lindtr-rarloua a»»i*ptioa» on tlit delayed neutron spectra

- 1 0 -

lafereacos: 1 . UTILJ., W.U\, and daH>I2, R.W., Hue. Sc i . Ens. 36, 115 (1969) 2 . Kitll i i , C.K., Fiiyaics of *»clear Une t i c s , Addinon-Hesley,

*ew "orx. (1965)

THE SOLUTION OF THE ONE-MMEIOIONAL. MULTIZONE. MULTIGROUf DIFFUSION EQUATION UMNG THE LIE SEMES METHOD: M. U u m k l and M. State.

The mil illmamilnnll G-group diffusion equation for a multizone reactor was solved, using the I I * ser ies J technique*

Hie flux vector at any point of the arbitrary zone z of the reactor i s given by a C x G transfer matrix Multiplied by the flux

(21 vector at the origin . Ibis Matrix; i s a product of the transfer matrices of the f i r s t z zones* I t la presented exp l i c i t ly for esch geometry separately - for slab and sphere with help of the trigono­metric functions, for cylinder with the help of the Vessel functions, whose arguments are matrices.

Toe c r i t i c a l equations were derived and, i n the case of the cuo-zone reactor, compared with the corresponding ones i n the monoenergetic reactor theory. Tie cr i t ica l s i ze s of several reactors having spherical geoaetry vera computed using the equations obtained. The calculations verc performed for two, three and four energy group approximations. The results vere practically the same as those obtained by the usual diffusion code.

- leimranc—. 1. aaaxu, W., Die U> Xelhea rod ihre Anwtndtxizeu, 2nd edition,

Hlssemscbaften, Jnrlin, 1967 2 . UZVOSSJ,. H., IUHEH, T. and TUTAE, S . , J . Hull. Energy,

Ji , 361 C1969)

THE SOLUTION OF THE THO-tHMENSIONAL, MULTIZONE, MULTIGROUf DIFFUSION EQUATION UMNG THE LIE SEMES METHOD: M. Lememhs.

lb* generalized U i aarlee with operator* of higher order* 1 ' was uead to solve the twc-dixamaional c-greup diffusion equation.

a) Bare t eae tw

The flea at amy point I s given by a G x G treesfor matrix multiplied by tea flax vector at the origin. l a the case of two-dimensional geometry this transfer matrix i s a product of two matrix fuactloas v i ta separable varlakleo. The saparatisa of the variables i s obtained by writing the buckling matrix I 2 a* a sua: I 2 . i 2 + g 2 , where J 2 and . ,* 2 are

- 11 -

called the axial buckling natricea. I t i s proved that they are cc=r.Jta-tiva and have the property L .

The c r i t i c a l equations were derived, and a s icple cochod given to calculate the cr i t i ca l s ize of a bare f in i te slab and f ini te cylinder. As in the case of one-dimensional geooetry, this oethod requires a knowledge of only the highest eigenvalues of the axial buckling tutrices In this, way the nultlgroup problem la reduced to a "pseudo 'one-group" problem. The expression for the minloua volume of the cylinder reactor was found.

b) liultizone Reactor

The transfer matrix was derived for a f in i t e slab and for a f in i te nultizone cylinder reactor with the multiple zones In the r direction. The transfer matrix for a two-zone, tuo-dlaensional reactor was ec=?ared with that In the raonoenergetlc reactor theory. The cr i t ica l equation was derived*

References: 1. GROEBNER, 'J. f Die Lie Keihen und ihre Anaendungen, 2nd edition!

Wissenschaften, Berlin, 1367 2, LEIANSKA, H., HAHED, T. and YIETAH, S. , J. Hud. Energy, 23, 361 (1969)

INTEGRAL TRANSPORT THEORY IN SPERIVAL GEOMETRY: L. Rnkefatein.

The solution of the Boltimann equation can be greatly simplified i f the sources axe isotropic and i f only the isotropic component of the angular flux i s desired. In this situation I t la convenient to s tart from the integral font of the Boltrmenn equation and ust the symmetry properties of the system as much as possible.

An Important c u e , and the eas iest one, i s one-dimensional plane glometry. I t has been solved sat is factori ly and used In c a l l calcula­tions . Other geometries wars treated l e s s sa t i s factor i ly . Dus to analytical complications severe restrictions had to be made .

In the present oork a complete treatment was derived for the inhomogameous spherically symmetric fas t reactor with isotropic scattering. The original six-dimensional integral equation la reduced to a two-dimensional one. An e x p l i c i t , calculable form of the kernel i s presented.

Reference: 1. GKCEKSPAX e t a l . Computing Methods in Itaactox Physic* , Gordo©

fc Bridge, Ksw York, p.239 (1948)

PUK METHOD - APPLICATIONS: I. Avksm and E. Gfeempen.

The theoretical aoael developed* * wu used In a est of t e s t celealatloaa aealeaad to inveaticate Che affect of spatial mods (K) U T i r l w oa the scalar flux distribution, and to compare the PL/JC method with radially i j s a i t r i c , aultieroup, S4 calculat ions. I t was mkavm that the quality of K-truncatioa i s primarily xnfluenced by the a l t l t ede of discontinuity juaps in the pleccvise constant croas aoctioa faectloas and by the number of point* of discontinuity with alternate s laas . Good agreement with to* resu l t s of tbc ZF1 laboratory at Coraell University was obtained for cylindrical-S4 and F5/7 calculations for simple hexaaonal c e l l s . More complicated fuel eomfigmratioas require higher X-approximations. For furtbtr Improve-. • e s t of che PL/t Method i t i s suggested that piecevise constant cross secdoas .he represented by truncated trigonometric polynomials with iTt-j-^t coeff ic ients which can be obtained froa a number of sueaabillty methods. I t i s a l so rsro—ended that a search for the most e f f i c ient aethod of solution of the FL/K systea of equations be pursued.

1. AVIUM, Z. and TEIVM, T-, Hud, Sci . Eag. ( in press ) .

FLUCTUATION FACTORS FOR THE THEORETICAL EVALUATION. OF AVERAGE :>.. NEUTRON CROSS SECTIONS OF FISSILE NUCLEI, IN THE UNRESOLVED RESWANCE REGION*1*; Y. Gur and Y. Yiftsh.

i ' - - * ,

In reactor .calculations i t i s necessary, to use evaluated neutron cross sections i n the region of unresolved resonances where experiaea-t e l date are lacking. The evaluated cross sections are calculated ,, from the nuclear s t a t i s t i c a l parameters given as basic data i n evalua­ted nuclear data f i l e s such ss KTOF/2, An important step i n these calculations Involves computation of integrals of the form* ' :

s*,„,„ - <1 +«*> /. a + 3 - ) | + i - . < 1 + . 2 > E # + I

r n / ff, T^, r - width of mutton, f l n l a a , | « u ind t a u l iwonnic* m p t c t i w l y . IhHt i n luppll id by thi j n l i u u d

r r a i te lwt dita H I * , » , k •• ^ , -p=- r««i)«ctlT«ly ;

IJ, n • nunber of degrees of freedom for neutron and fission u ld t i 2

X dis t r ibut ions . These, too, are supplied by the data f i l e s .

These Integrals are called "fluctuation factors" ox "fluctuation integrals" and ar ise from s t a t i s t i c a l considerations. Up to cow they have not been plotted or ' tabulated in the ent i re range needed. In the present work these quanti t ies were calculated and plotted for f i s s i l e material in the range 0 . 1 < a < 51 and 0 .1 < b < 163 , with aa accuracy of 12 or b e t t e r .

Since the integration methods of Gauss Laguerre or Heznite Ichebysheff do not work in this case, Simpson's integration bad to be used. Writing the zero-to-infini ty in tegra l (symbolically I(o,«) ) as 1(0,c) + I ( c , « ) , the in tegra l 1(0,c) was calculated, giving t(0,°0

. l ie .

1 - exp(-c) * F o r * e s s t h a n ^ truncation error c > 4.6 i s enough, while for less than 0 . 1 A truncation error c > 6.9 i s enough. In the present work a value of c - 6.4, corresponding to a truncation error of l e ss than 0.172, was taken. The accuracy required in the numerical integrat ion was IX. In the f i r s t computations, computer time on a Fhilcc Transac S-2000 computer was 12 odn for about 200 out of the 2400 integrals needed, i . e . 2.4 hours for the en t i re j o b . A big improvement was obtained by performing the integration piece-wise, which reduced the to t a l time to 3.5 minutes, representing a

i i i MINI i i i nun i i i nun

OS ° " ^ h"Tr V " V - 2 ^ ^ ^ <

P 0 8 ^sT~^\ . o 5 / / / / / / / -* 5 ^ ^ ^^——*^?o$/ / / / / / •

0.7 * ^ ^ 0 ? A K / / / / 0.6

- ...

' ' • F i g . 1 '

St*tisticil ftctor S f ' u ' » fmctioo of th« itaclitieal p n m u t b for various valuu of th« p«r««t.r «, vtth • • ( > l « d » f " i i ' !

- H -re unction factor of about 40. The results for the f i r s t 200 integrala war* identical l a th« two cases. A sample of Che results i s given In t i t . 1-

lefoconcat a 1. CM, I . mi TIFTAB, S . , IA-1208(ln press) 2 . aiCHOLSOM, fc-B., The Dopplar Effect In Fast Neutron Buctbrs

(Thesis). APIA 139 (I960)

NUCLEAR DATA FOR Pu-240, 241, 242: M. Kansr

Horfc baa baen dona on the Modification of codes for the theoretical calculation of neutron cross sections. The code NEASREX for calcula­ting ine las t ic , capture and f i ss ion cross sections was made into a stib-

(2) routine of the code ABACUS-2 , which computes tota l and shape e las t ic cross sections. An addition was made to HEABREX in order to calculate the differential compound e las t i c cross section o__(0); this was done by assuming the shape of the partial cross section o „ ( l . , j , I 1 , j \ J ; 8 ) to be the sea* as In the simple Hauser-Peshbach theory. - For the calculation of the f i ss ion cross'section, the l inear dependence of the f iss ion width on energy was replaced by the expressions of the, channel theory of f i s s ion .

The combined code Is to be used mainly for f i t t ing data In the keV neutron energy range.

Inferences: 1 . HOLDAUDt, r . A . , ENGELBRECBT, C.A. and DUFFT, G . J . , AHX-6978 (1964) 2. AUHIACI, I . E . , Preprint 9ML 6562 (revised 1964) i

FAST SPEEDER REACTORS FOR DESALINATION* 1): $. Yjftah. "

A study wee Bade of Che above topic, Including the following aspects: why f ss t reactors,, activations for developing fas t reactors, nuclear desalination, and nuclear energy centers. The aaln conclusions reached vera the following:

a) There i s almost universal agreement chat fast reactors w i l l be the main power producing reactors ss from the beginning of the 1900's1.

b) Only fast breeders aeeav to offer a solution to the triple )»r>*la* ef ef f ic ient use of aaturel uraalu* resources, tons of by-proeutt plutomiam, and hundreds of thousands of tone of depleted uranium, n s n l e s s with excellent potaatial for power costs which are lower Yjiam either seevoaHnaal plants or thermal reactors.

- 15 -

c) The delay in building nuclear desalination plants and the big effor ts in developing fas t breeders suggests that these reactors w i l l be used for desal inat ion a t qui te an ea t ly stage and wi l l eventually become the sole source of power in tills f i e l d .

d) The ult imate t e s t of fas t breeders i s whether they can produce e l e c t r i c i t y a t a cost of 2 mills/Kwh or lower, compared t i l th the present cost of about 4 mills/Kwh from thermal r e a c t o r s .

e) If a cost of 2 raills/Kwh. or lower i s achieved, t h i s w i l l bring about a new i n d u s t r i a l revolut ion, making possible the development of energy-intensive indus t r ies in which low-cost energy i s the nain ray mater ia l .

Reference: 1. TCFTAH, S . , Paper Presented a t the S.E.A.S. Symposium on Economic

Aspects of Energy Production with Par t i cu la r Reference to Nuclear Power, London, 12-17th Aoril 1969

POWER AND WATER. FEASIBILITY STUDIES: J. Ad* 3~ - 'I '

1. A single-purpose nuclear power station -±- "*"" • A feasibility study for the erection of a single-purpose nuclear

power station in Israel was carried out jointly by a teas composed of members from the Israel AEC and the Electric Corporation. The study compared the costB of constructing and operating a nuclear and conven­tional power station of 300 MWe for operation in 1976. The following aspects were covered: site, potential reactor types and suppliers. preliminary timetable, estimates of capital costs and kilowatt-hour cost, etc. Thrae different reactor types were considered: heavy water natural uranium, heavy vater enriched uranium, and light water reactor.

2. A dual-purpoia power and w t « r desalinating plant A feasibility study for the erection of a dual-purpose plant

with net saleable output of 300 MWa and 40 million gallons of vater per day was prepared by a teas, composed of members from the AEC and the power and water utilities. The study covers estimates for nuclear installations with different reactor types» as well aa estimates for conventional heat sources, and for the desalting, plant.

NUCLEAR PHYSICS

The level schemes of Ge, As, Cd, La and Pr have been studied via the (Y.Y 1) reaction, excited by resonance scattering of neutron capture gamma rays. In addition, a systematic study of the level widths and parameters of the resonant levels has been carried out. In the spectra of scattered gamma rays from the (Y.Y*) reaction in 1 8 4 » 1 8 6

w > 203,205 T 1 a n d 209 M a Q a n o m a l y w a s f o u n d ) v e r y similar to the anomaly observed previously for (n,y) and (djjjy) reactions.

The investigation of the systematics of (n,Y) reactions in the natural titanium isotopes has now been completed. Evidence of direct capture in the Ti(n,Y) reaction was found.

Measurements of elastic scattering of 9 HeV gamma rays by Pb, Th and U targets confirm the Delbruck scattering imaginary amplitude, with a probable contribution from the real amplitude.

DYNAMIC INVESTIGATION OF THE CORE EXCITATION MODEL. J Ra;cwski

An attempt i s being made to account for the unusual succen Che core excitat ion model ' . A 'J > s ta te of an odd-even : can be expressed as

j.Jc J

where j is the spin of the odd nucleon, J c the spin of the even-even core and J the total spin of the state. The core excitation codel assumes that due to the weak coupling of the last nucleoa to the core all the a's except one are snail. A self-consistent treatment * relating various electrodynamic and electrostatic properties of an odd-even nucleus indicates the existence of simple core excited states even in cases where spectroscopic factors from (d,p) and( He,d) reactions show that the states are much nore conplicated (ianv a's contribute) *

Another interesting problem under investigation is the influence of the added nucleon on the core states. Eliminating the couopole-monopole force effects we can get an experimental indication of such influence from the discrepancies from the center of gravity theorem ' Collectivity of the core states implies that there is no such influence, and if it nevertheless exists the question is why does the (collective) core excitation model work. An early attempt to investigate these problems within the formalism of R.P.A. and T.D. approximations proved unsuccessful. An attempt is being made to investigate the problems within the framework of simple solvable models.

References; 1. DE-SHALIT, A., Phys. Rev. 122, 1530 (1961) 2. BRAUNSTEIN, A. and DE-SHALIT, A., Phys. Letters 1.,264 (1962) 3. LAWSOH, R.D. and HRETZKY, J.L., Phys. Rev. 108, 1300 (1957) 4. BLAIR, A.G., Phys. Let tern .9, 37 (1964) 5. THANKAPPAN, V.K. and TRUE, W.W., Phys. Rev. 137, 793 (1965) 6. AGASSI, D., Ph.D. thesis, Weizmann Institute of Science,

Rehovoth,1967

CALCULATION OF ENERGY LEVELS IN THE 16 < A < 21 REGION:

V within the franework of the shell model^ . Following the work of Arima et al. we assumed that nucleona out of the 0 core fill the Id, . and 2s, .„ orbits. The energy matrices were calculated and the least aquares method used in order to find the best values of

If air—atera ot tma effective tve-sody Interaction. Arime at * 1 . fomnd these values by f i t Cine tha axel tat ion energies of the lavela la th is region; they obtained a good f i t to the apectra, but their valmes of the two-body parameters do not reproduce tba binding energies vary v a i l . Vc triad to f i t tha binding energies of th« levels in th is ration, but i t turns out that the f i t to the spectra becomes worse, cape d a l l y for The change in the parameters i s considerable, end their values ere not well determined.

The energy leve ls of 2 0 f t c , namely 0**(g.s.), 2 + <1.61 HeV), * + (4.25 tfeV), 6 + (8.79 HeV) and 8 + (11.99 MeV), were also calculated using the deformed orbital* method * . The deformation parameter was determined by minimi Ting the E - < *,[**[*. > / < * j l * j > and was foond to be nearly the sane for a l l J . The wave functions obtained by th is method were compared with those of the shel l model.

Keferences: 1. DC-SHALIT, A. sod TALffi, I . , Nuclear Shell Theory, Academic Press,

lew-York, 1963 2. AlDtA, A., COflFJT, S., LAWSON, E.D. and MAC~FAILAnT, H.B., Nucl.

Phys. A 108. 94 (1968) 3. M A , I . , Phys. l e v . 132, 2225 (1963)

f ''' DELBRUCK SCATTERING OF 9 MaV GAMMA RAYS: G. Ben-David, R. Moreh and D. Saizmam.

Tha e las t i c scattering of 9 HeV gamma rays from a Ni(n,y) source by Pbf Th and V warn measured at forward angles between 8* and 20". This measurement presents a problem because of the very low coumting rates and relatively high background expected at forward scattering angles. "*ie experimental system i s shown in Fig. 1. A 30 cc G«(Li) detector was used.

The e las t ic scattering cross section at the angles measured i s expected to contain coherent contributions from Raylaigh scattering, nuclear resonance scattering, nuclear Thomson scattering and De lb ruck scattering. In order to measure tha contribution of Delbruck scattering, i t i s therefore necessary to know tha contribution of the other scattering processes. In general each of these processes i s described by a complex scattering amplitude which contains a real and an Imaginary part, and these have been calculated 1 * . From a comparison of the calculated to ta l cross sect ion with experiment, i t was concluded that: a) a contribution of the Imaginary amplitude of

Delbiuck scattering ex is ts ; b) destructive interference cecum fcetvti Rayleigh and Dolbruck scattering; c) there cay be a centristLcn of the real part of the Delbruck scattering ospl'tudo.

Fig. 1 Experimental arrangement for neasuring scattered " garma rays

JACKSOS, K.E. and WETZAL, iC.J., Phys. Rev. Letters 22, 1008 (1969) EHLOTZiOf, F. and SHEPFEY, G.C., iiuovo Cine a to 33, 1185 (1964)

PRECISE MEASUREMENTS OF ATTENUATION COEFFICIENTS OF GAMMA RAYS

IN THE 7 MeV REGION*1*: R. Morah, D. Salznwin and Y. Wand.

Total atomic attenuation coefficients of monochromatic photons from an Fe(n,Y) source were precisely measured in various elements,

(21 employing a new method described previously . In this method tlie elenent i s interposed as an absorber between tlie game source and a resonance acatterer. The latter acts as an accurate energy analyzer for the genua rays emerging from the absorber, since only photons of undiminished energy, i . e . which have not undergone any inter­actions in their passage through the absorber, w i l l be resonantly scattered. THUS a l l collimation problems and di f f icul t ies of small angle scattering corrections are eliminated.

The results for 15 elements between Be and 0 , for tvo gamma energies, are given in the table. It i s seen that the measured coefficients are systematically higher than the calculated values, the difference-increasing with Z up to about 22.

lecai total »7T-THT1T1 "ajfac i—is ( * / ? " • ) co—ersd with S I c « U t l U S ) . fir eoatoa oaerilos 7Y279 ani 7.646 HeV

I i T

- 7 .279 HeV E • 7 .646 HeY I £ e f . 3 l e f . 4 P r e e e a t work Raf. 3 BeE. 4 Preeent work

Be 28* .5 2 M 2 8 4 . 2 + 3 . 3 277 2 7 8 . 6 2 8 1 . 7 + 2 . 1 C 4 4 6 . 1 M S 4 5 1 . 3 + 2 . 3 4 3 5 . 7 4 3 7 . 5 4 4 1 . 0 + 4 . 6

Al 1111 1122 1125 + 5 1094 1105 1096 + 5 w Z327 2342 2340 + 5 2312 2325 2332 + 8

F« 2750 2779 2772 + 6 2738 2764 2.'83 + 9 Co 2899 2916 2925 + 10 2888 2902 2945 + 9 HI 3048 3073 3072 + 5 3039 3061 b )

C» 3202 3233 3239 + 5 3194 3221 3245 + 6 Zo 3358 3393 3391 + 5 3351 3381 3412 + 10

*« 6462 6550 6617 + 15 6494 6576 6697 + 24

c» 8910 9027 9052 + 8 8974 9086 9182 + 24 l a 12730 12900 12996 + 26 12850 13000 13206 + 30 PI 15300 15470 b ) 15450 15590 15923 +• 17 Bi 15600 15770 15955 + 14 15760 15890 16223 ± 1 5 a 18470 18570 18706 + 21 18640 18740 19026 ±1?

e) Values obtained by In-ta Interpolation between 6 and 8 MeV b) Tola elonint was found to be a nuclear resonant scstterer of this

photon energy

References: 1 . tDPXIi, > . , SALZHA3H, D. and WA3D, ¥ . , Phys . L e t t e r s 30B, 536 (1969) 2 . HMtEU, 8 . , BALEttHM, D. and WAND, Y . , I n IA-1190 ( 1 9 6 9 ) , p .27 3 . PLECUUV. Z.J. tod IE1UULL, J.*., UCM.-50400,Vol.4 (1968) 4 . SIOHH, E. and ISXafZ, H . I . , LA-3753 (1967)

PARITY DETERMINATION OF RESONANT LEVELS EXCITED BY TITANIUM CAPTURE GAMMA RAYS: R. Monh, O. Shohel and A. Wolf.

The linear polarisation of resonantly scattered genu rays wis •eaewred.uelng a Conptoa po lar iae ter ( 1 ) . The gaeaa bean v«s obtained by tkorael aeutron capture in Tl and was resonantly scattered by dif­ferent targets. Ike laetraneotal isotropy of the polarlMter waa checked using I I and Cu scatterars which are known to yield a ralua of 1.0 for the esyaaetric ratio, owing to their isotropic angular

• 21

distribution. Fro* the measurements the El end MX nature of the scattered radiation, which ia related to the parity of the resccjcce level, was determined. The results, together with the spies of the levels, are summarised In Table 1. It is seen that ooac resonance levels decay by £1 radiation.

TABLE 1 Properties of levels populated by resonance scattering of Tl capture ray a; J and J denote Che spins ot the ground

and resonance levels

[Scattering f Ic^tope

Energy (SeV) o J"

r Transition

i 9 S*> 6.556 0 + r El ! " * > 6.418 0 + l" El

1 3 9 L a 6.418 7/2 + 9/2" El

1 18"W 1 6.160 0 + 1 + Ml 1 8 6 « ! 6.418 °+ r El

i 2 0 9 B 1 j 7.168 9/2 9/2 + El

Reference: 1. MOREH, R. and FRIEDMAN, H., Phys. Letters 26B, 579 (1968)

FLUCTUATIONS OF PARTIAL RADIATIVE WIDTHS IN NUCLEI EXCITED BY <Y?> REACTIONS: Y. Schtatinoar, G. Ban-David. H. Szkhman and M. Haas.

Transitions from resonantly excited high energy bound l e v e l s exhibit considerable fluctuations in intensity. These fluctuations can be explained as being due to the complexity of the transition matrix elementa, th i s leading to the known Porter-Thomas distribution ot the partial radiative widths.

As the ( Y , Y ' ) reaction la biased towards detection of l eve l s having large values of r and - ~ , we analysed only transitions to

o * the two lowest s ta tes . Moreover* as in most nuclei only one or two resonant leve ls ware observed ( in contrast to the resonant neutron capture results) we decided to investigate the. distribution of the ratio of the intens i t ies and not the distribution of their absolute values.

I t a*y be n o w that If the partial radiative width* obey a x'-type diMriaatloa with v degree* o£ freedom, tha ratloa ara distributed according to a C-typa distribution (or Flahar Z-distri-faatloa).

A i r f r i m likelihood analysis of tb« resonance levels leads to ava l s* .o f v - 1 .1 . A Ifente Carlo analysis shows that t i ers Is * probability of 35J£ of obtaining v laas than or aqual to this value for * population bavins 1 degree of freedon. The corresponding probability for a population luwins 2 degrees of freedom i s 62-

These results are in good agreement with predictions based on toe va l i c l ty o£ the Porter-Thoeas distribution law for the bound levels region, however th i s type of analysis cannot exclude the presence of structure effects in certain nuclei.

MEASUREMENT OF NUCLEAR LEVEL WIDTHS IN THE 6 - 9 MaV ENERGY REGION USING RESONANCE SCATTERING OF Ni GAMMA RAYS: G. Bsn-Dsvid, M. Hen, R. Morah and Y. ScMssinssr.

In earlier work, the widths of nuclear levels in the 6-9 HeV energy region war* •ensured in several nuclei by means of resonant scattering of Mi capture gaaaui rays 4 . The experiments Included measurement of: the scattered spectra, using a G*-L1 detector; the effective cross ssctiom; the se l f absorption ratio; the temperature effect . A computer coda calculated these effects as a function of the tota l radiative width T , tha total width I* (which for unbound levels includes the neutron width r ) , th« ground state radiative width TQ , and the energy difference tarn 6 . The value of r was taken as that which gave the beat f i t to the experimental measurements.

In the present work additional nuclei were studied. The results ara summarised in Table 1. I t should be noted that apart from tha S.99J (lev level In 150$m, a l l lavala ar* bound l eve l s . The values found are In qualitative agreement with Axel's prediction that these l eve l widths can be explained by means of extrapolation of the giant dlpole resonance peak ,

- 25 -

TAELC 1 Total radiat ive widths of resonanca levels

Scat terer Resonance energy (keV)

r (eV)

1 6 2 n M S e 8 6 S r

^ S n 1 3 0 l a 1 5 0 S „

7696 7820 7820 7696 7538 8998*

0.21 + 0.04 0.09 + 0.02 0 .1 + 0 . 0 5 0.12 + 0.06 0.24 + 0.06 4 + 0.5*

* This leve l 4s unbound; I t s t o t a l width i s 6.5 + 1.0 eV, which means that the neutron width i s T - 2.5 + 0.5 eV

n —

References: 1 . ARAD, B.» BEH-DAV1D, G. PELAH, I . and SCHLESEIGER, Y.

P h y s . Rev. 1 7 3 , 684 (1967) 2 . AXEL, P . » P h y s . RIJV. ,6 , 6 7 1 (1962)

USE OF A NEW HIGH RESOLUTION GAMMA MONOCHROMATOR: R. Moreh and A. Wolf.

A lead target which resonantly scatters the 7.26 IteV neutron capture ray of Iron was used as a source of variable energy radiation. The energy variation was achieved by varying the angle of the scattered beam . The energy resolution was 4.8 sin* eV/deg, where 9 is the scattering angle. These photons were used to search for new highly excited bound nuclear levels in various elements.

The element to be studied was placed in front of a 5" * 5" Hal detector which measured the scattered radiation intensity as a function of scattering angle. Any dip in the absorption curve would correspond to an energy level being excited In the absorber nuclei. A system of •ollec ilits was placed between the absorber and the detector In order to reduce the effective angular divergence of the acattired radiation to about 1.6*. The absorption curve was recorded automatically on a Multichannel analyser operating in a stultlscaler mode. (The time normalization at each point was obtained by placing a 1.5" * 1.5" Hal Monitor above the soller slits, so that it viewed the scattered radiation directly without the interposition of the absorber). Using this experi­mental arrangement, the angular interval between 90* and 150*, correspond­ing to an energy range of about 220 eV at 7.28 IteV excitation, was scanned in sen* 15 elements. Only on* absorption dip was found - in cadmium, at * scattering angle of 128*.' The abaorbar thickuess used was 35 g/cm

aski tha mist was about 3.5Z at I t s minimum point. Assuming that ths C H O -I M I IMCOV* is. C* i s of 25X abundance with « u r o ground s tats spin, a*4 that tm* rsmemamce txeitatioa occurs through dlpola absorption, then Cm* grousd state rsdlatiom width turns out to be 0*06 aV.

Ik* wiftlTTTTT of this method as a tool for studying tha width* of dleole rssomaaca levels and their spacing was found to he severely If mi res' by the relatively low counting rate. I t was thus very d i f f i cu l t to detect weak resonances, which are believed to ex i s t at such high e x d t a t l o * energies. Beference: 1. McllimE, J.A. and RAHDALL, J .C. , Fhys. U t t e r s 17, 137 (1965)

GAMMA RAY INTENSITY ANOMALY IN THE (TY*) REACTtONW :

R. Mofeh and A. Woff.

She spectral shape of the scattered radiation from (Y»Y') reactions in several isotopes in the region A < 20S was studied, in order to search for an anomalous intensity bus? at around 5 HeV. The analogue of this effect i s well Known in (n,y) reactions using thermal and resonance neutrons, and in (d,pY) reactions.

The present study uses the fact that resonance scattering events occur l a the Interesting suss region when the Pe(n,Y) and Ti(n,Y) reactions are used as gaasui sources. Hie iron capture gamma rays photo-

205 excite a 7.646 KeV level in Tl, and the titanium capture genua rays \J and two levels

Figure 1 shows the resonantly Besides the

e last lcal ly scattered peaks, narked by arrows in the figure, the anomalous high intensity peaks ars clearly evident near 5 HeV irrespec­t ive of the In i t ia l excitation energies involved. The bump i s smaller in the tungsten Isotopes than in the thalllun Isotopes. The fact that the bump can s t i l l be seen in the case of tungsten i s due to the presence of three resonance levels which contribute Independently to the 5 HeV region in this case. These spectra should be compared with that

150 scattered from Sai (not shown) using a l>'l(n,Y) gamma source, where very weak g a — transitions were observed in the 5 MeV range. As another example of a bumpless spectrum, the scattered radiation from 209

Ui i s a lso shown in Fig. 1, where one resonance at 7.168 HeV was

\ ^ ^ J U L y [ j ^ «> %

Fig. 1 Resonantly scattered gamma spectra from Tl, W and Bi targets, at an angle of 135*. The energy scale refers to the energy of the double escape peaks. Lines denoted P, F , correspond to photopeaks and f i r s t escape peaks. Others correspond to double escape peaks, with

the arrows indicating independent resonance l ines

The anomalous bumps in the gamma spectra from (n»y) and (d,pY) reactions are believed v ' to be due to £1 energy differences of the s ingle-particle energies across the shel l model orbi ts . I t was

(2) suggested that these bumps result from the decay of doorway states of the final nucleus. The corresponding configurations are formed in the (n,y) and (d»py) reactions through a leoi -direct proutss. I t I s very l ikely that the bump in the present case i s also due to El* energy differences across the shall Model orbits .

Refersncea: 1. MOREH, R. and WOLF, A., In "Hsutron Capture G U M Ray Spectroscopy"

. IAEA, Vienna, 1969, p.483 2. BARTHOLOMEW, G.A. «C a l . , Fhys. Letters 240 (1967) 47

STUOY OF THE ENERGY LEVELS OF " ' T l USING THE OX") REACTION: R. Monk. A. Not m l A. Wolf.

203 The energy lntli of XL were studied using elaatically mil

imelastically scattered gamma rays produced by thermal neutron capture in titanium. The scattering isotope < u Identified by using an iaotoplcally enriched thallium target. Toe scattered spectrum was

ired with a 20 cc Ge(Li) detector. crgy of the resonance level was found to be 6.418 MeV.

gaemm rays were detected, with energies above 4 MeV, which were 203 to be primary inelastic transitions to excited levels in Tl.

The energies of these levels are at 0.279, 0.671, 1.116, 1.236, 1.410, 1.452, 1.641, 1.671, 1841, 1.885, 1.900, 1.935, 1.988, 2.345 MeV. Five of these levels were identified with recently reported levels.

The total radiation width of the resonance level was determined by a self absorption and temperature effect measurement, and was found to be r - 0.35 ± 0.06 eV, with a branching ratio to the ground state f /r - 0.29. These results were Interpreted in terms of a model

(VI (2) suggested by Axel * , and were compared with previous results regarding radiation widths. The energy levels were compared with theoretical predictions obtained by coupling quadrupole and octupole vibrations to single-hole states. 203 .an anomalous intensity "bump" was observed in Tl, es was the

References; 1. AXEL, P., rhys. Rev. 126, 671 (1962). 2. HOIZH, R., and WOLF, A., Phys. Rev. 182, 1236 (1969) 3. HOME, X. and WOU, A., in "Neutron Capture Gamma Bay Spectroscopy"

IilA, Vienna, 1969 p.483.

STUDY OF LEVEL STRUCTURE OF M T I USING THE «Ti (TO,) REACTION: J. Tsneobaum.R. Monti, Y. Wand and G, Ben-David.

49 The gamma ray spectrum resulting from tharaal capture in Tl was measured using a 30 cc Ce(Ll) detector. Some 14 gam? Unas were seen at the following energies: 1,120 ± 0,003, 1.476 ± 0.003, 1.555 i 0.003, (2.212 1 0.007), 2.520 ± 0.007, 2.623 ± 0.007, 3.273 1 0.007, 3.640 1 0.007, 4.988 ± 0.007, 5.554 ± 0.007, 5.745 t 0.007, 6.055 ± 0.007,(6.758 t 0.007) 6.785 t 0.007, 8.261 1 0.007 and 5.382 ± 0.007 MeV. The neutron separation energy of

Coincidence and angular cor re la t ion -measurements, using two Nal de tec tors , were also carried out , permitt ing the construction of the decay scheme of Tl . The angular cor re la t ion r e s u l t s of the two cascades 10.938 + 2.675 + 1.555 and 10.938 - 2.675 * 1.555 - 0 are consis tent with the following spin sequences, where the mul t lpo la r i t i e s are given in bracke ts : 3* ( 1 ) , 4 + (2\ 2 + , and 3" (1), 4 + , (2), 2 + (2), 0 + , indica t ing that the 4 capture s t a t e does not contr ibute to the popula­t ion of the 4 2.675 MeV l e v e l . From t h i s r e su l t the following spins were determined for the 5 ° T i l e v e l s : ( 3 + or 4 + ) for 5,945, and ( 2 , 3 or 4 + ) for the l eve l s 4 .151 , 4.178, 4.887, 5.195 and 5.382 MeV. By comparing the t r a n s i t i o n s t rengths of gamma rays and proton groups from the (n,Y) and (d,p) react ions leading to the same l eve l s in T? i t was Foun>f that the contr ibut ion of d i r ec t capture to the 0» ,Y) reac t ion i s qui te appreciable .

THE LEVEL STRUCTURE OF 5 , T i STUDIED BY THE s°Ti (n.7) REACTION: J. Tenenbaum, R. Moreh, Y. Wand and G. Sen-David.

The gamma ray spectrum resu l t ing from ;: hernial neutron capture in Tl was measured using a 30 cc and 10 cc Ge(Li) de tec to r . Some nine

gamma l ines were seen a t the following energies : 1.030, 1.164, (2.189), (3.168), 3.216, 3.479, 4.190, 5.210 and 6.377 HeV.

Coincidence and angular cor re la t ion measurements, using two Nal de t ec to r s , were car r ied out i n tiro energy ranges! (a) 5.05-5.42 MeV, containing the 5.210 MeV l i n e ; (b) 4.00-4.42 HeV,containing the 4.190 MeV l i n e . The s ing les and coincidence r e s u l t s permitted the construct ion of the decay scheme. The ground s t a t e gamma t r a n s i ­t ion gives d i r ec t l y the neutron separat ion energy in x i . The value found was 6.377+ 0,007 MeV. The angular cor re la t ion measurements i n range (a) gave the r e s u l t A_/A - 0.022+0.015, showing tha t the d i s t r i ­bution i s i s o t r o p i c and y ie ld ing a spin value 1/2 for the 1.164 MeV l e v e l . The coincidence r e s u l t s for range (b) were not conclusive.

STUDY OF THE ENERGY LEVELS OF 7*G» USING NUCLEAR PHOTOSXCITAT1CN: R. Moreh and 0. Shahal.

thermal neutron capture i n i ron was used t o study the energy leve ls of Ge. The sca t t e red spectrum was measured using a 20 cc and 10 cc Ge(Li) de tec to r . The energy of the resonance l eve l was found to be 6.018 MeV, and i t s decay scheme was es tabl i shed by assuming t ha t the

- K -ala* — r o U I M U > m » i i a n due to primary traneltloaa de-excltlna. tlM r r n m c i l eve l . The aaerciaa of 10 levels v a n thue obtained, 4 #f wUeh ear a* identified vita ksovn level* in M fca. ID addition several law aaarjj transitions between lntaraadlk**.«. lavala vara faaarfffid B W w p l i r distributions of th« alaat ic and i n a l u t i c Tf—i war* aaaataiT and the spin of the resonance l eve l and f ive low-lying lavala determined. The parity of the scattering l eve l v u detaialasl vatlmg a Conpton polarlncter and vaa found to be odd, oorreapoadlac to El radiation. Since the spin of the 6.01S HeV level Is l " , i t I s eapeeted that the spina of a l l l eve l s populated by primary transitions are e i ther 0 , 1 , or 2 . The present work i s there­fore i iwaliMiilny to that oa the Ge(a,Y) reaction* * where the cap t u n s ta te i s e i ther 5~ or *~ and therefore nainly levels with spins of 3 , 4 , 5 and 6 are populated.

The total and partial radiative widths of the resonance l eve l were determined from measurements of the temperature variation, s e l f absorption, and absolute scattering cross sect ion. The width of the 6.0IB IfeV l eve l was thus found to be F > 0.12 eV, and VjT - 0 .19. Figure 1 shows the decay scheme of the 6.018 >leV-level and suaaarises the spectroscopic information.

Fig. 1 Decay scheme of the 6.018 HeV leve l of 7 4 Ge

gefarsnee; 1. HftCRUDEK, A.P. and SKTTHEK, U.K., Fhyg. K*v. 183, 927 (1969)

- } \ -

USE OF THE <**) REACTION FOR STUDYING THE ENERGY LEVELS OF T »Ai U I : R Morah and O. Shahal.

Ulas t i c and i n e l a s t i c nuclear re ionant s c a t t e r i n g of nsnach recycle photons from As has been studied usini; a 47 cc Cc(Ll) de tec tor , Tr.c gamma source was provided by thermal neutron capture in i ron . Hie energy of the resonance leve l i n As was found to be 7.645 iteV. Aasuslc;; the high energy l ines to be prinary t r ans i t ions da-exci t ing the resonance l e v e l , 25 energy l eve l s were found fron the ground s t a t e u? to 2.6 MeV. Seven of these nay be i d e n t i f i e d with recent ly reported l e v e l s . By measuring the angular d i s t r i b u t i o n of the sca t t e red r ad ia ­t i on , the spin of the s c a t t e r i n g l eve l uas de temined to be 1/2, and the" sp ins of 14 low-lying l eve l s were thus found to be e i t h e r 1/2 or 3 /2 . The t o t a l r a d i a t i v e width of the resonance l eve l was deterranec

and found to be T = 0.36 + 0.10 eV u i th r / r = 0.11 . In addi t ion , — o the p a r t i a l rad ia t ion widths of the 7.646 IleV l e v e l were deduced by measuring the branching r a t i o s fo r i t s decay. These widths *-ere used

Fi3- 1 Decay a chew of As

- 32 -

t* M U M U the raalatloa atreaaths of the ttaaaltioos. By comparing tmesm mamgrms vitfc the n l w i give* by Bartholomew*2' ee obtained from tae sjsremarirs of the radiation width* of high energy primary a-caetare gemma raya of kaowa awltipoUrity, i t vaa possible to Infar tarn ssdtlsolarlty aad tae character of the radiation. Thu* the multi-polarity of at least 10 transition* w found to be pradoainantly eHmale, o«C of wmlca $ are thoafbt to be El transitions* Sine* the ratnaaara l eve l i s 1/2, therefore tnc corresponding levels have a •v ia of either 1/2 or 3/2. These results are susamrlzed in Fly. 1,

1 . HOKEC, X. aad SH&IIAL, 0 . , P a y s . Rev. 188 (1969) 2 . BeJtrHOLOHOf, G . , Aon. i t er . H u c l . S c i . 1 1 , 259 (1961) 3 . nuclear Data. Bl-6-80

STUDY OF, THE ENERGY LEVELS OF m C d USING NUCLEAR PHOTO EXCITATION:

R- Moreh and A. Nof .

e las t i c and inelast ic scattering of iron capture gaaata rays was used to study the energy levels of Cd. Besides the e l a s t i c Una a t 7.632 HeV, some 19 Inelast ic l ines were found,- corresponding to fcnoun levels in Cd. Another very weak c l a s t i c Line at 7.279 lieV was excited, but no inelast ic transitions froa i t s decay were observed. The angular distributions of the e las t ic and ine las t ic transitions vera neas tared, frost which the spins of the levels were deduced (sea Table 1 ) . The parity of the scattering l eve l was aeaaurad using a Compton pol&rlmster and was found to be odd, corresponding to El scattered radiation. In the l i t e r a t u r e * 1 ' 2 ' 3 * the 7.632 + 0.517 llaV decay i s reported to contain between 1.97 and 5% of a quadrupole admixture. Therefore the analysis of angular distributions to a l l 2 levels was done with particular attention to possible H2 admixtures In the El transitions. These admixtures ware found to be almost entirely absent, and certainly less than 1.52 for a l l l" •*• 2* transitions. The tota l sad partial widths of the 7.632 HaV l e ve l

112 In Cd were determined from Measurements of the temperature variation, s e l f absorption, and absolute scattering cross section. The results were r * 0.088 eV and r /r - 0.55 .

- 33 -

TABLE 1 L I M tMrglei and lavel cnetgiea in 1 ]^Cd «a obt*ln«d from tiic <I<c<j

of the 7.632 MeV l»vel excited by Pa capture g o — ra?a

Y-Line Energy Branching Level Energy J* (MeV) Ratio X (MeV)

7.632 58.0 0 0* t 7.015 11.5 0.617 2+ j 6.410 7.5 1.222 0+ 6.345 0.5 1.287 6.203 2.0 1.429 o+ : 6.136 1.7 1.489 2 + '• 5.765 11.2 1.867 0+ | 5.551 0.5 2.081 5.515 0.5 2.117 i

' 5.478 0.4 2.154 5.406 0 .1 2.226 5.337 0.5 2.295 5.127 0.4 2.505 4.913 0.2 2.719 4.804 1.5 2.828 0+ 1 4.786 1.7 2.846 2+ ; 4.525 0.4 3.107 (1.2) j 4.442 0.2 3.190 (1.2) 4.388 0.5 3.244 (0) ! 4.326 0.5 3.306 l

References: 1. MICHALK, V.E. and HcINTYRE, J.A. , Hud. Phys. A137. 115 (1969) 2. CESAKE0, R. ec a l . , Hud. Phys. A132, 512 (1969) 3 . ESIBS, G.P. and MIM, K., to be published

STUDY OF THE ENERGY LEVELS OF »»La USING NUCLEAR PHOTOEXCITATION:

R. Morah and A. Nof.

Xlaatlc and Ine las t ic scattering of gamma ray* waa used to 139 atudy the high and low energy leve ls in La. Two o p e r a t e gamma

sources.fromthermal neutron capture i n Fe and in Ti , vara aaajliiyad. With the iron aourca three independent resonance l i n e s at 6.018, 7.279 and 7.632 HeV vera excited, of Which only the 6.018 HeV l e r e l via strongly excited. With the titanium aourca tvo indepaadent rosonancee at 6.760 and 6.418 HeV were excited. Ho attempt was made here to deduce new lavele due to the ambiguity of associating a gMhen gamma transition with a apecific resonance l eve l . Therefore only transit ions to known low-lying l eve l s were considered.

The angular distribution waa measured at several eagles between 90 and 160*, and the spins of 3 re«aaaca . lavs l s aad S lcv- ly i»g l eve l s wars determined. The parity of the 6.018 and 6.418 kaT leve l* was

• M m ! miat a r f ri» islartMfsr *•* zaaai to so add, cornaaaailH ta at ssattarsi r*dl*H»*i Ik* aUtla of t>m I m l i m <•*•«• fas*. oawnHOU o< tat t—stuafiwi of foot, salt akaoraMotj aai rtnlatl oaaoo aactla*. Ik* raaalta KOTO r(».01»> - 0.051 *», r /r - o.5«! r(».*i«) - o.ou *», r /r - 0.71. n» •*> results • o

riaorllH t** rsiim*r* aad low-lylaf tarsia art *u**srl*ad la th* table.

M i l i.i»« **a o - n u n rf " V tarl* *a obtal—d vlth H M H »

—tni . c a f r * «*—a aourcaa

E n t I (sir) J 1

0 7 / 2 +

0.166 5 / 2 +

1.220 5 /2 , 9/2 1.3M 7/2 , (11/2) 1 .U9 7/2, 11/2.. 1.536 7/2 1.580 9/2 2.232 7/2 , 11/2 6.0U 7/2" 6.418 9/2" 6.760 7/2

THE LEVEL SCHEME OF ""La, STUDIED BY PHOTOEXCITATION WITH THERMAL NEUTRON CAPTURE GAMMA RAYSM: H. Slichnian, Y . SoMssinaar, G. Ben-Dovid and D. P * l l .

Nttclaar rasonsat scattering of photons xrom ssvarsl (n,-y) rcactlono vaa used to study bound nuclear levels In tho 6 - 9 MoV Melon In 1 3 5 La. Ihe dasxcttatlou of six ruonant levels at energies 6115, 6418, 6760, 7637, 1527 aad 8582 k«V was investigated. Fro* the angular distribu­tion of tha elastlcallT scattered photc-is, a spin of 9/2 was deduced for the 6115 and 6418 IceV Impels.. Oe tha basis of the angular dietri-butlon of tha inalsstically scattered photons tha following spin asalgn-•snts van aada for four of tha low-ljrlng level*: 1219(9/2), 1421(7/2 or 11/2), 1687(7/2) and 1770(9/2). Hitherto unknown levels vara found at 1894 and 2159 IceV. Total radiation widths wara aeasured and found

- 35 -

co ba 22+7 M V for the 6115 keV resonant level , iC*10 mV'tat eftc 6413 k«V level and 3J+15 M V for the 6760 k*V UyU

Reference: 1 . SZICHMAN, U . t SCHLESINGER, ¥ . , 3ES-BAVID,G. n d PAV£L, 0 . ,

Nucl. Phya. (In preas)

THE LEVEL SCHEME OF , 4 t P r STUDIED BY PHOTO EXCITATION WITH NEUTHQN CAPTURE GAMMA RAYS: G, 8tn-Darid, O. Pavel, V. Schtaingar and H. Sxidunvi.

Resonant levels were excited in T?r uaing * natural praseo-dymiua oxide target and capture ganaa rays froa chlorine, copper a=d seleniua sources. Angular dis tr ibut ions uere measured a t 90* and 135* using s 30 CD Ge(Li) detector. The resonant levels studied were located a t 6115 {chlorine source), 7236 (copper) and 7138 (seleniua) keV.

Tiia following sequence of low lying levels in was deduced: 145, 1125, 1261, 1289, 1327, 1433, 1456, 1602, 1666, 1760 and 1S99 keV. Preliminary calculations permit a spin assignment of 7/2 or 9/2 for the 1456 keV level .

Further studies including measurements of the widths of the excited s ta tes and the use of additional (n,Y) sources are i n progress.

SOLID STATE PHYSICS AND METALLURGY

The summaries contained in this section reflect the broad spectrin of theoretical and experimental problems treated in this field during the past year.

Group theoretical and Green's function techniques have been employed in the study of the nature of second-order phase transitions and the behavior of magnetic systems in the vicinity of phase changes. A modified variational method was used for the determination of the wave-function of solid He, and a unified approach was derived for non-radiative decay processes in large molecules. Several theoretical treatments were applied to the analysis of the optical properties of solids. In connection with diffusion problems in the solid state, a theory was developed for the Interaction between an impurity and the host lattice,

Experimental studies, using neutron diffraction techniques over a vide temperature range, have been carried out on se-eral magnetic compounds. Particular attention was paid to the rare earth ortho-ferritea and to transititn-metal chlorides. For this research progran, techniques were developed for the preparation of single crystals and powder specimens. Neutron inelastic scattering techniques were employed for the study of the ferroelectric behavior of hydrogen-bonded ferroelectrics as a function of tenperature.

The temperature dependence of the elastic constants and ultra­sonic attenuation of the rare earth metals in single-crystal and poly-crystalline form was studied, and the observed anomalies were correlated with the magnetic transitions of these metals. The experimental data permitted the calculation of the magnetoelastic contribution to the total energy of the lattice.

Mb'ssbauer effect studies were performed on cubic Laves-phase actinide compounds and on ferroelectric substances. The purpose was to determine 'hyperfine fields, charge states and possible magnetic or electronic transitions.

The g-factor of tha first excited atate of F« KII determined by mtaaurlmf the precession of the angular distribution of resonantly scattered gamma rays under the Influence of an applied Magnetic field. Simllvr studies were carried out with a gamme-ferrice scatterer.

The properties of tCl and IBr isolated in a frozen argon matrix were studied by the Hossbauer effect in I. The Investigations heva oov been completed and permit en evtluAttoa of the bond character of these molecules. In addition, studies were carried out on a series of iodine-fluorine compounds.

The temperature dependence of the electron spin resonance spectra of MgO doped with rhodium and iridium were measured and analyzed, Huclear magnetic resonance measurements were carried out on several compounds and hydrides of titanium, and the data were used to determine the diffusion coefficients of hydrogen in these hydrides as well as the activation energy for this process. The radioactive tracer method was employed for the determination of the diffusion coefficients and diffusion mechanisms of copper and zinc in praseodymium and of cobalt In beta-uranium.

Several studies were carried out In the fields of physical and mechanical metallurgy, for instance the determination of the kinetics and mechanism of the precipitation hardening process In aluminum-rich alloys by means of ultrasonics, hardness testing, and electrical * resistivity. A program was initiated on the metallurgical behavior of UjSi at high temperatures. This compound Is of great potential t-->ortancft as a nuclear reactor fuel. In order to Improve the thermal ansfer properties of uranium oxide, a chemical nickel plating process

*>as developed and studied under various operational conditions.

- 39 -

WAVE FUNCTION FOR SOLID 3He: R Thiebergsr and I. Zmora.

In the case of solid tie, the atomic mass i s snail and so arc the attractive forces between the atoms. As a result one cannot use the classical methods of latt ice dynamics when calculating the properties of sol id He,

Several calculations of the ground state energy have been carried out using a variational method based on a tr ia l wave function of the Jastrow type. In one of these calculations t ie wave function i s found by terminating the cluster expansion at terns of the second order, for small separations between the atoms, and using the

(2) Frohberg wave function for large separations between the atons.

Work i s now in progress to improve the wave function obtained previously , avoiding the use of the Frohberg correlation function.

References: 1 . BRUECKHER, K.A. and TTIIEBERGER, R. , Phys . Rev. 178 , 362 (1969) 2. FR003ERG, J.H. , Ph.D. Thesis, University of California,

San Diego, 1967 (unpublished)

THE ENERGY GAP LAW FOR RADIATIONLESS TRANSITIONS IN LARGE MOLECULES^: R. Englman and J. Jortner.*

A unified treatment WEB derived for nonradiative decay processes in Uirge molecules which involve either electronic relaxation between two electronic states or uniaolecular rearrangement reactions in excited electronic states . This treatment follovs the formalism previously applied to the l ine shape problem in nuclear recoil and in the optical spectra of sol ids. It was possible to derive theoretical expressions for the nonradiative decay probability so that an arbitrary number of different molecular vibrations can be incorporated in the vibrational overlap factors.

The general expressions obtained were reduced to analytical form for two limiting casta, which were denoted the strong coupling l imit (corresponding to a substantial horizontal displacement of the potential energy surfaces of the two electronic states) and the weak coupling l imit (where the relative horizontal displacement of the two potential energy surfaces i s small). Quantitative criteria for the applicability of these two coupling limits were specified. In the strong coupling l imit the transition probability i s determined by a Gaussian function of the energy

• T«i-Avb \>.lw«n1ty.

-40 -

fttiittr (AE-X.), where AE is the energy gap between th« origins of the t w elactromlc stateu and 21^ is the Stokes* shift. This Halt exhibits a generalised Arrbeniee type temperature behavior where the transitlorn probability depends exponentially on th« energy barrier for the intersection of the two potential surfaces. At low temperatures the transitlem probability is determined by tha mean vibrational frequency and Is expected to show only a Moderately weak deuteriiai isotope affect. The weak coupling limit reveals an exponential (or rather seeer-exponentiaiy'dependence of the transition probability on the energy gap AC. In this limit the transition probability is dominated by the highest vibrational frequency (e.g. the C-H or C-D vibrations) and is expected to exhibit a Barked isotope effect. When semi-empirical estimates of the pre-exponential factors were inserted, the theoretical expressions for the weak coupling were found to be in reasonable agreeeent with the available experimental data on electronic relaxation in large organic molecules.

leference: 1. EsCLHAK, K. and JOtHZt, J . , Hoi. Fhys. (1969), In press

GENERALIZED REDUCTION FACTORS FOR THE JAHN-TELLER EFFECT ON A DOUBLET: B. Hsfcmrin and R. Enfknan.

Formulae for the reduction factors q and p of the Jahn-Teller effect operating in an o rb i t a l doublet have been derived. These Incorporate the effects of both the l i nea r and higher order couplings*.

Reference: 1. HALPEIIM, B. and ENGLMAtfp %., Solid State Cossi. (1969), In press

OPTICAL PHONONS OF SMALL. CRYSTALS^: R. Ruppin and R. Enghnart.

In experlsentsl studies in which the Infrared properties of ionic crystals were examined using small samples - in powder form, in colloidal suspension or'crystsls in the shape of thin layers - the peculiarities due to size end shape have not always been properly recognised. The Infrared frequencies of the msterlal derived without regard for these peculiarities may be in error by some tens of wave-numbers. We have Interpreted the ganeral characteristics of the experimental spectra of about one hundred compounds*1', and analyzed In detail representative infrared measurements of some twenty compounds In the light of the theory<2>.

- 41 -

References: 1. For example, McDEVITT, N.T. and RADN, W.L., Spectrochin. Acta, £0,

799 (1964) 2, ENGUttN, R. and ROPPIH, R., J. PhyB. Chem.,Proc. PhyB. Soc. 1^

1515 (1968)

MASNETOELECTRIC EFFECT IN DOUBLY POLARIZED SYSTEMS: H. Yatom. In analogy to the slnultaneous manifestation of magnetically and

electrically polarized phases , it can be expected that as a ferro-magnct undergoes a ferroelectric phase transition, the usual disconti­nuity in the electric susceptibility will be acconpanied by a disconti­nuity probably somewhat smaller, in the magnetic susceptibility- One reason for this is the abrupt change in the exchange tern due to the change in the ionic distances resulting fron the onset of ferroelec­tric! ty. An expansion of the exchange integral will contain a tern proportional to both the spontaneous electric polarization and an externally applied electric field. This tern will give rise to a magnetoelectric coefficient in the free energy.

By applying the Green* s function technique in the random phase approximation, the saturation electric polarization and the magneto-electric susceptibility uere calculated as a function of tecperature. The system chosen was a PerovsJcite-type ferroelectric, in which the directions of the spontaneous magnetic and electric polarization coincide.

The magnetoelectric susceptibility i:as investigated for an anti-ferroelectric-antiferronagnet with four magnetic atons per unit cell, where only two of them are subjected to equal but opposite ferroelectric displacements (antiferroelectric). Formulae for the magnetic and oagnetaelectric parallel and perpendicular susceptibilities were obtained aa functions of temperature, using the molecular field approximation. These quantities were computed for the six possible combinations of the following cases: the magnetic transition tempera­ture is greater than, aquaX to, or lass than the electric transition temperature; tha electric transition is of the first or second, order.

A model for an antifsrromainet with spins in the form of a canted •piral was developed to yield theoretical formula* for tha magneto-electric susceptibility in terms of microscopic parameters.

Reference: 1. KOGIMSttlA, Tu. E. , VINEVTSCV, Tu. H. and ZHUUWT, G.S. JtTP

( R U M . ) 48, (5) 1224-32 (1965)

SIZE EFFECTS ON PLASMON-PHONON MODES IN POLAR SEMICONDUCTORS^: R. Rwppin.

The coupled plasmon-optical phonon modes in a finite sample of a degenerate polar semiconductor uere studied in the long wavelength Unit. Toe novel feature resulting from the finiteness of the crystal i* the existence of surface modes. The contribution of these modes in the infrared absorption spectra of small samples was computed. The effects of the application of a magnetic field were also investi­gated.

Raference: 1. Huppin, 2., J. rhys, Cl.em. Solids, 30, 2349 (1969)

THE SOLUTION OF THE BOLTZMANN TRANSPORT EQUATION FOR A SINGLE PHONON MODE IN SOLIDS, WITH MOMENTUM CONSERVING COLLISIONS: J. Amran (Suwnann).

The Boltzmann. transport equation for a s ing le plionon node I s written

[k+vH'-M coU

'.there the l e f t hand side £s a differencial operator on the distribution function f (x«j>) representing the change due to the flow of the wave packets, and the right hand s ide la an integral representing the changes due to co l l i s i ons . The phonons are treated as wave packets with energy e - av and •omentum p - hit .

The usual Chapman-Lnakog series of e x p l i c i t Integra-differential equations for terms in the ser ies development of f, cannot be applied to bosons . For bosons and femions a l inearization process Is s t i l l poss ib le ' by putting f - £ Q + j f 0 ( f 0 + 1 ) , with fQ being a local equilibrium distribution function. Assuming l inearisat ion we gat two equations:

(Right Band Side) (f ) - 0 and

(ft * V fe)f " (Uiilt H"4 S t d , ) «o ' i> whsre In the aacoad aquation tli« l e f t hand aide contains £ Instead of £ 0 (differing ehue froa tii« cane of •olaculte in » gaa). TIic condition for the n l i t i a u ot » aolutiw la given by hydiodynaaic equitiona.

- 43 -

For e lec t rons we can wr i t s f Instead of f on the lef t hand aide We have shown e x p l i c i t l y th.lt the Chapman-Enskog cethod la app l i ­cable only for c l a s s i c a l p a r t i c l e s . Further we showed that the above-mentioned l i n e a r i z a t i o n leads to noaphysical r e s u l t s for phonons, at low temperatures. The ohysical reason for t h i s I s the nonconservation of the number of p a r t i c l e s , which* contrary to the requirements of the Chapaan-Enskog method, cause3 f, - (f - f ) , which i s the deviat ion fron local

l o equil ibrium d i s t r i b u t i o n , to contr ibute to the energy and conentun dens i ty . Therefore the hydrodynamical equations must be s a t i s f i e d by f + f,, and not by £ alone as i n c l a s s i ca l gases . ( I f we t ry to s a t i s f y them with f only, we lose physical ly meaningful so lu t ions l i k e the s t a t i ona ry hea t f low), l h i s leads to the appearance of second d e r i ­va t ives i n the hydrodynamical equat ions . The i n t e g r o - d i f f e r e n t i a l equation for f, now contains f- on the l e f t hand s i de too - which leads to deviat ion from the gas - l ike behaviour. References: 1. HUANG, K., S t a t i s t i c a l Mechanics, John Wiley, 1963, p.142 2 . SHSSHAHH, J.A.. and THELLAHG, A. , Proc. Phys. Soc. 81 , 1122 (1963) 3 . 2EIAN, J .M., Electrons and Fnonons, Clarendon Press , 1960, p.275

THEORY OF THE INTERACTION BETWEEN AN IMPURITY AND THE HOST LATTICE: J. Amran (Sussmann).

The potential acting on an impurity Imbedded in a host lattice is usually divided into two parts: 1} a static potential, arising from adiafaatic considerations, neglecting the Motion of both the Impurity and the at=ms constituting the host lattice, *i> s. *i=c dependent potential resulting fro* the coupling of the Imparity with the elastic vibrations of the host lattice. This tine-dependent potential ia assumed to be small and treatable as a perturatloa. In a general way it can be said that the above assumptions would be reasonable If the mass of the impurity were several orders of magnitude smaller than that of the atoms constituting the host lattice. This situation.t however, does not occur*

Analysis of the problem has shown the dependence of the potential on the state of motion of the Impurity, and led to tha Introduction of two concepts, namely the "accommodation time" (the time necessary for the potential to change after the impurity has made a transition) and the "effective mesa" of the impurity. Some experimental results can be explained in the light of these new concepts.

RATE CONSTANTS OF OPTICAL EMISSION IN RUBY*'); B. Banwtt and R. Engtaan.

I.

vibrooie state* in a i-uby-like system was investigated over several decades of time.

Zbe time variation caa be interpreted in terns of four physical 4

processes which cause the depletion of the lowest T~ vibronic state in the course of t ine: A) thermal excitations of the system to the excited T. vibronic s tates; B) T_ -»• E tunnelling;

4 C) radiative decay to the A, ground state from the vibronic system after i t has attained thermodynamic equilibrium; D) a steady radiative depletion of the T_ vibronic s tates operative through­out the whole time. Processes A, B and C are a l l accompanied by the last process D.

The rate constants of the processes are given by the height i f

the plateaux in the plot of dt 0.5 and I

against time (a*- „. 1 ) . - 1,0, where I i s atasored The curves for temperatures T

la units of the characteristic vibronic frequency, show three plateaux, which correspond to the processes A, B and C in chronological order. Under certain circtsmitances, e .g . at low temperatures, process B i s absent and A goes over directly to C » as in the curve for T - 0 .1 .

F l f . - l - Rata of change of occupancy of the lowest T- vibronic state mm a function of time

The R-line ftntjnaity i s due to process B„ which Is observable experimentally by measuring, the build-up of the R-line in the nano­second region <2>

Referencesi 1. BARMETT, B. and ENGLMAN, B., J . Luminescence ( in press) 2. POLLACK, S.A., J . Appl. Phys. .38, 5083 (1967)

ZERO-PHONON TRANSITION AT THE M + CENTER IN NaF: J. Nahum.

The if center in IlaF I s associated 1"'' ' ' with an absorption band at E = 1,671 eV and an emission band at E = 1.336 eV. The a e absorption band, when measured at low temperature, shows a weak zero-phonon l i ne at 813.5 my together with a p a r t i a l l y resolved vibronic s t ruc tu re approximately regularly spaced (Fig. 1 ) .

(2> The in tegra ted absorption s trength of th i s l i ne re la t ive to the band a t T =» 0"K i s I /L * e~ . The value of S , the cos t probable number of phonoos involved in the t r ans i t i on , i s es t ina ted in t h i s way to be about S = 6 . The value of S can be es t ina ted in other ways too, from expressions involving the frequency u charac ter i ­zing the modes dominant i n broadening the t r a n s i t i o n : a) from S - (HCO)/2.36 4fu) , where H(0) i s the zero-point width of the band; b) from S - A/2Kw)» where A i s the Stoke's s h i f t , when the luminescence

- \ \ i * i

BO - \ \ -

\\ 60 A

A 0O26ev

40 A \\ \ \ 0027eV

iX>

i

A A 1 1 ^ 1 / \

770 790 810 WQvtltnglh (mp)

Vibronic structure of th* H c u t t i in fl«F at 4*K. Curve a - absorption •pcctrae; curve b - excitation spectrum for eidsslon «t 1.336 eV

- 46 -

and absorption of the band correspond to transitions between the same electronic l eve l s . The following experimental values of H(0) were obtained at 4*X; H (0) - 0.177 eV for the absorption band and H (0) * 0.155 eV for die eaission band. From (a) the corresponding S values are S *» 8 and S *» 6 , using the phonon energy of 4fw - 0.O27 eV derived frost the vikronic structure of Fig. 1. The Stoke's s h i f t A - E - £ * 0.335 eV, as determined experimentally, yields S * 6 .

The fact that these different aethods, and others, give about the same S value suggests that the coupling to a s ingle phonoa node involved i n the M center in the ground s ta t e and the excited s t a t e , i s strong enough to dominate completely.

References: 1 . ittHCM, J . , Phys. Rev. £74,1000 (1968) 2 . FITCKEN, D.B., SILSBEE, R.H., FULTOtf,T.A. and WOLF, Etf.L., Phys.

Rev. Letters 11, 275 (1963)

£SR SPECTRA OF Rh IONS IN SINGLE CRYSTALS OF MgO: A. Raiznwn, J.T. Suss and S. Szapiro.

2+ 4+-In the present work the ESR spectra of Rh - and Rh were studied.

Single crystals of MgO doped with Rh were grown by the flux •ethod. The crystals were investigated in the X-band, at 12, 20 and 77"K. Two d i s t inct ESR spectra were observed. The f i r s t has a g-value of 2.171 and A - 12.0 (10~ 4 cm" 1), and i s ascribed to Kh 2 +

which has a 4d electronic configuration. This spectrum can he observed at 77*K. and below. I t s l ine width i s narrowest in the [HIJ direction. The l ine width anisotropy indicates tetragonal distortions of the cubic crystal l ine f i e l d . The second spectrue

la observed after gaaau irradiation of the crystals , and has a -U —1

g-value of 1.667 and A - 31.5 (10 c a t ) . The g -value ia charac­t e r i s t i c of a 4d configuration in a strong octahedral f i e l d , which •ay be regarded aa a s ingle hole in a t_ orbit* . This s p e c t r a i s eas i ly saturated at temperatures below 77*K, I t s features indi -

4+ cat* that i t i s due to a Rh ion. There are approxliutaly 10 times 2+ 4+

M many ions at Rh s i t e s aa at Rh ones. Mfarencaa: 1 . LOU, W, aad SUS2, J . T . , Solid State Coauun. 2 , 1 (1964) ?. GBirriTflS, J.H.E., OWEH, J. and WARD, I.M., Froc. Roy. Soc.

(London) A 219, 526 (1953)

ESR OF l r 4 + IN MgO: W. Low* and J.T. Suss

4+ The ESR spectrum of I r in s ingle c Gamma i r r ad i a t i on produced two types of ESR spec t ra . One, having a cubic symmetry, could be described by the spin Hamilton!an

^ a 8 3 H . S + A I . S

with S * 1/2, I = 3V2 , and g = 1.74, A => 25.5 (10~ 4 e n " 1 ) . The other spectrum, having a tetragonal symmetry, could be described by an axia l spin Hamiltonian

ft - 8,| B \ S z + S i 3 (H K S x + H y S y > + A S z I 2 +

+ F'S_ I_ + S I )

with g = 2.26, and g = 1.46,

These spec t i

cubic and te t ragonal c rys t a l l i ne f ie] ' respect ively. The spectra were invest igated in the X-band, a t 77°K and 20°K. No resonance which could be associated with I r ions was observed in the c rys ta l s p r io r to i r r a d i a t i o n .

THERMOLUMINESCENCE AND ESR IN BORON NITRIDE: A. Katzir and J.T. Suss. An inves t iga t ion of the thermoluminescence and electron spin

resonance of boron n i t r i d e has been s t a r t ed . Commercial grade samples obtained from various sources were i r r ad ia ted by gamma rays and X-rays a t room temperature. All samples exhibited complex thermoluminescence and ESR spec t ra . The correla t ion between XI and ESR i s being s tudied in order to obtain an understanding of the defects in BN .

MOSSBAUER STUDY OF MATRIX-ISOLATED IODINE COMPOUNDS: C. Goldstein and

T. Bar-Noy (Birnbaum).

The e lec t ronic s t ruc ture of IC1 and IBr molr-ules tr^ppr-' ' -129 argon matrices was investigated using the Mtfssbauer effect in I .

The following values were obtained for the quadrupole coupling constants and isomer s h i f t s :

The Hebrew University. Jorusolen

- 4 8 -

Far IC1 - m 2 * ^ 2 7 ! ) - - 2»7S + 10 K c / u c ; l .« . (ZaTe aomrca) * 1.20 + 0.02 an/sec

Far Mr - « 2 « Q ( Z 2 7 D - - 2736 + 10 He/ate; l . a . (Zal« »OUTC«> - 0.977 + 0.021 mm/sec

TW ajmadraaole £ov»ll*f constants arc s imilar, within the range of error, to those obtained for tbeae molecules fn the gas phase by the •tcronatftt techniane, From th« above data and the zero value found for the asjuaetrT parameter ( q - O , the characters of the IC1 and IBr bonds were deduced.

The r e c o i l l e s s fract ion of IC1 In ergon and I - In Icrypton was measured as a function of temperature and the Debye temperatures were found to be 49 + 2*K and 37 + 2*E respect ive ly .

MOSS8AUER STUDY OF IODINE-FLUORINE COMPOUNDS: S. Bukshpan, C. Gokartam, J. Soriano and J. Shamir.

129 The Mossbauer effect. In I was used to Investigate the structure of XTy l*7% t r t and IF^ ' l p 2 ' . The symmetry of the IFg Ion was found to be octahedral, In agreement with other measurements. A poss ible structure was proposed for the IF? Ion. The values of the quadrupole couplings, laooer s h i f t s , acd the asymmetry parameter are presented In the table . From these values the character of the 1-F bond was deduced.

TABLE 1 Wflisbauer parameters for lodlnc-Eluorlne compounds

^ Q C 1 2 7 ! ) IIC/HG

Isoaar s h i f t (ZaTe source)

• • / s e c Agyii 11'/ paraneter

n

» 3

» 7

I ( 6

+1073±2 -148 ±4

0 -141*

+3.0 -4 .56 -4 .68 +2.45 0.98

aaferencee: 1 . JIKSHPAH, S . , C0LDSTEH, C , SOEUNO, J. and SHAMIR, J . ,

J . Chaa. thy: 51, 3976 (1969) 2 . BlKSHMit, 5 . , MRIAHO, 3 . and SHAMIR, J . , Chen. Phy». l e t t e r s 4,

MX (1969)

HIGH TEMPERATURE PHASE TRANSITION IN K H z P 0 4 TYPE CRYSTALS: J. Grinbtrs. S. Livin, I, PeUh and E. Wiener lAvnesrJ.

In * previous work new phase transitions were found In *32K>4

type crystals at high temperature, these results were confirmed by other lavestigatore * * . lhe work was continued by studying the infrared rsf lect ion spectrum of KD.FO..

Sharp changes in the Infrared reflection spectr-ja (250-4003 en"" ) were found at the seme temperatures where the die lectr ic constants showed discontinuities. Two changes were observed, the f i r s t at 110*C, above which the spectra resembled those of the aonodinic KD-2Q,, and the second at 180*0, above which they were identical with the spectra of KH2F04 above 180*C.

Hie new spectra remained unchanged even when the tenperature was reduced to that of liquid nitrogen. A crystal of KIUPO, heated above 180 *C and then kept at room temperature for more than two years (without any special precautions) also shewed the same high teaperature s p e c t r a . However, in another crystal of EOLjPO heated beyond 180*C and l e f t to cool to room temperature, when a fine layer was scratched froa the surface the crystal beneath revealed fee usual spectrura of S^?*0* * E

room tenperature.

I t seems that KB?*0* c h * n S e s m t U 3 * c t a t n e monoclinie structure. Ihe corresponding temperature for HM^O. i s assiaed to be beyond the temperatures reached in this work (200*C) '*At 180*C the transition i s connected mainly with the B0, group, as i t i s not affected vher H la replaced by D , or K by Rb ^ . T!te spectrum above 180*G i s probably only the spectrum of the surface layer, and a decomposition l ike K H 2 P 0 4 "*" K P 0 3 + H 2 ° ** y °ccur. In order to prevent the escape of water from the crystal cur Esc*, an experiment was performed in an atmosphere of water vapour. A different spectrum was seen but appeared smeared. Further meaf»ur*mtnts ire in progress. Reference*;

1 . GRINBERG, J . , LEVIN, S . , PELAH, I . and WIENER, E. , Solid State Comm. 5, 863 (1967)

2. BLlNClR., DIMIC, V., KOLA*, D., LAHAJNAR, G.„ STEPISHIK, J.„ ZIMER, S . , VENE, X. and HADIZI, D., J. chess. Phys. 49, 4996(1968}

3. BLXNC, R., O'REILLY, D.E., IKTERSOH, E.H., and WILLIAMS, J.H., J , Cham. Phy«. 50, 5*08 (1969)

4 . 0'OKPE, H. and PEWI»0, C.I. , J . Phy«. Che*. Solids J28. 1086 (1967) 5 . RAPOPOtT, E., (in prea.)

MMMAUEH EFFECT STUOY OF THE FERROELECTRIC PHASE TRANS IT K)N OF

KH2FO4 TYPE CRYSTALS: M. Bn«*m*i, J. Grinbara, I. Fatah and E. Wiener.

e lectr ic mode of VM2^°U» ™ieh should appear in this crystal near the Curie point '£ ' . Co impurity was made to diffuse into a iX,PO, single crystal . A single crystal was used in order to be able to Measure the die lectr ic constant and thus the temperature in relative to T . The diffused region of the crystal was revealed to be polycrystalline as no directional effects were found in the spectra. I t was assumed that the Co iapurities take the potassium s i t e s in the crystal, as found by Oteni e t a l . ' in an K.S.rU study of Kh PO doped with Cu iapurit ies , -which have the sane radius.

The Hossbauer ef fect i s sensit ive only to low frequencies, of the order of oagnitude of the resonance width, so that i t was necessary to build a system uitii a high temperature s tab i l i ty which could be aaintained for long periods, (measuring periods of 3 days were needed in vieu of the low act ivity of the crystal and the smallness of the il&ssbauer e f f ec t ) . Tne L-Zsebauer spectrin of &1.E0, was neasured near T , and the d ie lectr ic constant was measured simultaneously to find the teoperature relative to I . Temperature s tab i l i t y was + 0.1*C,aod chaQges of 0.2*C were nade between successive spectra. Ihe spectra-were f i t ted by computer to tnree Lorentzian peaks. One peak, having an intensity of 1.5%, appeared with a small isomer sh i f t (0.06 sm/sec) re lat ive to the potassium ferrocyanide absorber, This peak i s probably due to Fe . The other two peaks, which appear

2+ to belong to Fe , are smeller and exhibit quadrupole sp l i t t ing of 1.74+0.03 mm/sec with an isomer sh i f t of 1.75+0.03 mm/sec. There was no significant change in the quadrupole sp l i t t ing or in the isomer s h i f t with temperature. In the region within 0.4*C above I , there was a broadening of the peak* by 252, and a decrease of 20* in the itossbauer fraction.

Ihese results can be explained by the existence of a ferroelectric mode whose frequency decreases to zero as T Is approached. This mode i s probably created by the coupling of the proton col lect ive mooV ' with the K - P optical •ode* 2 *. The proton tunneling s tops"* below the transition and the coupled mode Is frown out, leaving the K - P displaced from their symmetrical s i t e s above the transition. The low frequency which was observed in this experiment i s of the order of 1 mc/stc; this Is the lowest frequency of the soft mode observed so far in ^ ^ c r > ' * t a l « *

A similar get of oeaauieaenta wag carried out on KD.FO crys ta ls -

I t has been established that In th i s crysta l the etaweling frequency

I s lower, and therefore the order Is of longer range. The col lect ive

frequency I s be t t e r defined and changes over a wider temperature range

near X can be expected. Indeed the r e s u l t s , which were l a general

s imilar to those for KH.PO,, showed changes over a range of 1.2°C as

compared with 0.4"C In Ki,PO,.

Seferencesi

1. HIKY, J., PfiLAH, 2. and WIENER, E., J. Qien. Phys. 3, 2332 (1966) 2. KQBAYESill, K., J. Phys. Soc. Japan 24, 497 (1963) 3. COCdRAcI, W.„ Advan. Phys. 9_, 3S7 (1960), 10, 401 (1961) 4. CINADER, G., ZAMIR, D. and PELAH, I., Solid State Coco. .6, 435 (1968) 5. OTAill, A..and MAKISIKaA, S.t J. Phys. Soc. Japan 26, 85 (1969) 6. AZOULEY, T., GRUBERG, J. and WIENER, E-, J* Fh. Chem. Solids 28,

843 (1968)

STUDY OF THE FERROELECTRIC BEHAVIOUR OF HYDROGEN BONDED FERROELECTRICS BY NEUTRON SCATTERING: I Pefah, H. Zafrir, U. Efron and

This study is being conducted by two neutron-scattering techniques, namely cold neutron time-of-flighfc measurements and single crystal monochronator spectrometry.

The study of ferroelectric T.G.S. (triglycine sulphate, in powder form) by measurement of Che cold neutron scattering spectra above and below the transition temperature T (49*C) has been continued. In this connection the inelastic scattering spectra from glycine were measured in order to identify the inelastic peaks appearing in the T.G.S. spectra.

Another experiment being carried out in the time-of-flight facility is a study of the inelastic spectrum of RbH,P04 above and below its high, temperature phase transition (T * 86*C).

The ineleatlc scattering of neutrons from XH-FO. around 400 cm" has been investigated in the vicinity of T (- -150*0. Tor thii purpose the single crystal monochromator facility was used to obtain neutrons with preselected incoming energy, and the intensity of the scattered neutrons was measured within an energy window of 5 - 0 MaV (the "lnvertad beryllium filter" method). The data are now being processed.

Another investigation now in progress is a study of the scattering of neutrons by a KH-PO, single crystal at very low scattering angle* ( K + 0) near the critical temperature.

MECHANISM LEADING TO FEHROELECTR(CITY INDUCED IN CENTROSYMMETRIC

CRYSTALS BY ANTI FERROMAGNETIC TRANSITIONS: S. Goshen, D. Mukamtl.

H. Shikari and SLSMrikfMn*

lb* appearance o|E fcrroelectrlcity in conjunction with para-magmetlc-to-anti ferromagnetic transitions In centroeymmetric crystals vas considered. Ferroalsctrlcity Is forbidden i n centrosymmetilc crystals . However such crystals may loose chair center of syiawtry ma * result of a magnetic transition, and hence ferroelectric l ty .which Is forbidden In the paramagnetic phase, amy appear In the Magnetically ordered oae. To i l lus tra te this effect frc* the symmetry point of view, an antiferromagnetic transition in n structure belonging to the space group rmma vas considered In de ta i l .

An estimation of the ferroelectric aonent in a model crystal with some "reasonably real" properties yielded a moment of

-9 2 trlO Coul/cB! . I t was also shown that a discontinuous change i n the die lectr ic constant nay appear at the transition point due to the ferroelectric moment. This discontinuous change i s expected to

LANDAU'S THEORY OF SECOND ORDER PHASE TRANSITIONS: S. Goshen, D. Mufcamalt and S. Shtrikman*

Landau's theory on. second order phase t rans i t ions 1 •* s ta tes two limitations on the symmetry of the system below the transit ion: a) the symmetric part of T , where T i s the Irreducible representation according to which the transition occurs, must not contain the unit representation; b) the product of the antisymmetric part of Tr and the vector representation must not contain the unit representa­t ion.

The val idity of the second condition was discussed from the theoretical point of view by Dismwck* ' and Shen-Jue-Lien* » who •"•tasted I t be omitted from the theory. Furthermore, hel icoldal magnetic structures, not allowed by this condition, have b«*n observed experimentally"'. Dayaloahinalcii*5* triad to derive the condition i n a way different from that of Landau but did not obtain the same resul t .

We have derived the second condition starting from the basic Ideas sugieated by Dxyaloehinskii. We have a l so shown that with a

Wvfcnwn Imtftum of Stitnoj, flthovoi.

- 53 -

proper physical Interpretation of this condition the appearance of helicoidal structure can be understood.

Referencea: 1. LANDAU, L.D., LIFSHlTZ, E.M., Stat is t ica l Physics, Pergason

Preaa, 1959, Ch. XIV. 2. DJWHDCK, J .0 - , Phys. Rev. 130. 1337 (1963) 3. SHEH-JUE-LIEN, Chinese J. of Phya. .22, 77 (1966) 4. CORLISS, L.N., HASTINGS, J.M., J. App. Phys. 35, 1051 (1964) 5. D2YAL0SHINSKII, J .B. , Soviet Pfays. JEPT, 19,960 (1954)

HELICOIDAL MAGNETIC STRUCTURE OF A LINEAR ATOMIC CHAIN: S. Goshen. D. Mukamel and S. Shtrikman*

The magnetic structure of a linear chain having the paramagnetic syiaaetry C, i s under study. The Hanilconian asscaed for a chain in the z direction i s :

3 <• - J I S -S _ - D-y S x t t - a J (S 2 - S 2 ) 2 L n n+1 *• n n+1 *• nx ny n n n *

where the f i r s t term i s the Heisenberg Interaction, the second is the Dzyaloshlnskii term (D i s parallel co the r axis} and the third is an anlsotropy term. The. helicoidal structure resulting from this HamHtonian and I t s compatibility with Landau's theory of second order phase transitions i s now under consideration.

MOSSBAUER EFFECT STUDIES OF INTERMETALLIC IRON-ANTIMONY COMPOUNDS: M.P. Daritl.M. Friadrich* and S. Shtrikman*

Single-phase FeSb and ?eSb_ compounds vera prepared and identified by means of X-ray powder diffraction and electron nicroprobe techniques*

The compound PeSb has been reported to exhibit both ferro-and antifarromagnetic behavior up to 500°c. MBaabauer effect studies indicate however that no magnetic ordering takes place down to 7SDK. A strongly temperature dependent quadrupole sp l i t t ing was observed, which decreased fron l-< wm/aac at 73°K to 0.96 mm/aec at 770°K. The small isomer shift (+ t 0.3 mm/sac) was only s l ight ly temperature dependent. The temperature dependence of the quadrupole apl i t t ing i s surprising in view of the diffarent bsbavior of the isoatructural compoundTeSbj.In the ?*Sb compound a small quadrupols sp l i t t ing (0.2 mm/sac) was observed at 300°k\ At 7fl°Kt broadening of the absorption peak in *eSb indicatea the poss ibi l i ty of the onset* of magnetic ordering. Additional HBaabauer effect atudiea at 4.2°*t, as well as magnetic susceptibil ity measurements, sra belme carried o«c

* Waiimann inotiluM of Scfwic*. RtMvM.

la oraer to talk further Information on the electronic structure of these eoepouoda.

*tffffftc«:

1. BOSOWIST, T. Acta Hat. 1 , 761 (1953)

MOSSKAUER EFFECT IN FERRITES: D. Ksdwn and T. Rotnsm.

HSaabauer •easuraaents on ferr i tes of the type He Me' ^ O , and (feFe. M 0 , twhere >ie,:ie* are bivalent cations and II a tr ivalent

2-x x A v J

cation) were concluded. Tne substitution ae ta l s -nere ;ig and Co for lEe, and un> Cd and Zn for Ifc'j for II the aeta ls Cr and Al were used. Toe •easureaents were talcen both, at room and at l iquid air tempe­ratures.

Ferrites of hexagonal structure were also investigated. These ferr i tes , of general fonrnl* tiere.-D- uere made with Pb, 2a and Sr, and irere also aeasured at both room and l iquid air temperatures. The analysis of the experimental data i s in progress.

MAGNETIC FIELDS AT NUCLEI OF MAGNETIC IONS IN IRON AND FERRITES STUDIED BY RESONANCE SCATTERING OF NUCLEAR GAMMA RAYS: T. Rothtm end B. Locker'

As the f i r s t step in thia study, the g-factor of the f i r s t excited s ta te of Fe uas determined* This was done by measuring the angular distribution of »in ganca rays scattered resonantly from an iron ring* and observing the change brought about by applying a magnetic f i e ld to the iron •catterer, The applied f ie ld causes a precession of the magne­t i c oontnt at tlie nucleus about the direction of the f i e l d . ily taking measurements with the external f i e l d applied in two opposite direct ions, tii« magnitude of the e f fec t i s doubled. The value of the £-factor i s derived fron a tnoyledae of both the l i fet ime of the excited s ta te and the ef fect ive magnetic f ie ld acting on the iron nucleus. A value S - 0.50 + 0.08 was found.

X similar measurement uas performed using a gamma-ferrite (Y-Pe.0.) acatterer. -The experimental results are being analyzed in the l i gh t of the known structure of the gasaa-ferrite .

• tv-llw UMWMlty

MOSSBAUER EFFECT STUDIES OF THE CUBIC LAVES ACTINIDS-IRON INTERNET ALLIC COMPOUNDS: E.R. Baumingw*, J. Gal, 2. Hadari, I. Nowik and 5. Ofer"

Several cubic Laves actinide-iron interoetal l ic compounds such 33 u*Fe_, NpFe, and PuFe2 were studied, ut i l iz ing the Kossbauer effect resonance absorp-ion technique, Hyperfine f ields at the Fe nucleus and at the Up nucleus have been deduced. From the Mossbauer effect pattern the directions of the easy magnetizations in the above cubic Laves phases were determined.

CHARGE STATES OF Np RECOIL ATOMS FOLLOWING ALPHA DECAY: J. Gal, Z. Hadari, E. Yanir, E.R. Bauminger* and S. Ofer*

The llossbauer effect was ut i l ized to determine the charge states of the Np ions in various An sources. The charge states were found to be +3 in a l l sources containing the An ions in frozen solutions» and +4 and +5 in a l l oxide sources. In oast other An salts the sip took on the valence of the host l a t t i c e .

SUB LATTICE MAGNETIZATION IN YbFe0 3 and YFeO s AS OBTAINED BY NEUTRON DIFFRACTION AND ITS RELATION TO THE HYPERFINE FIELD: H. Pinto, G. Shachar and H. Sbafctd.

A comparison between the temperature dependence of the hyperfine f ield and that of the sublattice magnetization has been made by Van Loef and by Van der Vfoude e t a l . ^ in the case of various ferrites and iron garnets. Van loef found that the hyperfiue f ie lds are systematically lower than the sublattice magnetization, by up to about five per cent. Van der Wbude et a l . , on the other hand, found these two curves to follow each other very closely . The purpose of the present work was to Investigate this relationship in the extensively studied orthoferri teV .«>

The temperature dependences of the sublattice magnetisation of YbFeO_ (T - 630*K) and of YTeO_ <T U * 6«'K) were determined between

3 D J « 300*K and 680*k from neutron diffraction. In both compounds the magnetizations vere found to follow closely the published hyperfine f ie lds determined in MBaabauer effect experiments. According to these results the bypcrfine coupling constant varies by less than one per­cent. References: 1 . VAN LOW, J . J . , P h y s i c s 3 2 , 2102 (1966) 2 . VAN DOLWD0DB, T,, SAWATOT, G.A. and MQWIISH, A . H . , Fhys . Rev.

1 6 7 . 5 3 3 (1968) 3 . EIB3CHUT2, M., SHTRIKMAN, S . and TREVES, D . , Fhys . Rftv. 1 5 6 , 562

(1967) " Hrtmw Unlvtniiv. JmiNhm.

NEUTRON DIFFRACTION MEASUREMENTS OF POWDER YbFt0 3: Z. Friedman, a Kn«o, H. Sheked and S. Shtrikman*

YWeO. In one of the rare earth orthoferrltes and belongs to the m

apace (roup finer '. It ia Kntifenromagnetic.with a Reel temperature T~ * *30°K and antiferroaagnetic mode G. Magnetic aeaaurements ahow the existence of a weak ferromagnetic component along the {001] axis et room temperature. At about 8°K this component changes to the [100] axis. Neutron diffraction measurements were performed at 670°T, 77°C, *.2°T and 2°K. The lattice and the site parameters were calculated from the 670°K diffraction pattern.

According to the Dzyaloshinsky Morlya interaction and to the •agnatic measurements^ ' the expected magnetic modes for 77 K and 4.2°K are G and G respectively. The Intensity ratio of the magnetic lines 1(011)/I(101) v u 3 tt 77°K, in agreement with G^; however the intensity ratio at 4.2°K and 2°K was 1.3, in disagreement with the expected ratio of 1 corresponding to G . A ratio of 1.3 would mean that the antifetromagnetisa has a component along "a" and this will result in a ferromagnetic component along "c";-but this is In disagre­

ed ement with magnetic measurementsv '. The possibility that this discrepancy is a result of snisotropy in the form factor due to coralamcy effect! Is being investigated, References,: 1. TREVES, D t , J. of Appl. Phys. 36, 3 1003 (1965) * 2. BOZ0RTB, R.M., KRAMER, V. sod SEMEIKA, J.P. Phys. Rev. Letters

i, 3 (195ft)

WEUTHON DIFFRACTION STUDY OF POWDER TIMnCI 3 : G. Schacfcar, H. Pinto, M. Metsmud, J. Makowky and H. Sheksd.

The cry«tellegraphic structure of TlMnCl„ as observed by X-ray .<« diffraction st roost teasperature^ ' i i cubic with a lattice constant

a « 5.025JL The space {roup is fk3st, with atoss in the following positions: 11 (la) 000; Mn (lb) JJJjCl (3c) ££o , 0$,$ , 4<>£ .

The neutron diffraction spectrua at toon tsaperature shows at laaat two llnaa that ara not In agreement with the above atructure. Thaa* supetlattlca lines ace temperature dependent and decrease aonotonicallT aa the temperature is increased above 300*K. At 330"K the neutron diffraction spectrum agrees with the cubic structure. The liquid helium temperature and liquid nitrogen temperature patterns

' WMimtn InMhutt of Sctonca, Rrfravoi.

show two addi t ional lines. The appearance of aupet la t t iee l ines can ba explained by a temperature dependent displacement of the chlorine atoms. Our preliminary resu l t s Indicate chat the space group of the dis tor ted s t ruc ture i a Fbaa with four molecules per unit c e l l , the l a t t i c e constants are a - b *• 7-1068 and c - 10.058. The neutron diffract ion data show that the compound TltfaCl, ia paramagnetic at room temperature. TlHhCl- undergoes a t r ans i t ion to flatiferromagne-tlsra at 1^117'K. The existence of the magnetic l ines 101 + Oil leads to the conclusion that the magnetic mode i s G . Since a • b , i t i s impossible to determine the spin d i rec t ion i s a powder neutron diffract ion measurement.

References^. 1. Z0DKEV1TZ, A., HAKOVSKY, J . and KALMAN, Z.H., p r iva te cqcraunication 2. FRIEDHAH, Z . , HELAMDD, A., MAKOVSKX, J . and SHARED, K., PhyS. Rev.

(in press)

NEUTRON DIFFRACTION STUDY OF POLYCRYSTALLINE SAMPLES OF Rt£MnCI 4 AND Cs 2MnCI 4: A. Epstein, E. Gurevitch, J. Makovsky and H. Shaken.

The compounds RbjMnCl^ and Cs^fiiCl^ are i sos t ruc tura l to KjHiT^* . This s t ruc ture belongs to the tetragonal space group DTI - 14/mmm with two molecules per unit c e l l . The compound K_KiS, orders ant i fer roaagnet l -cally (T„ ~ 97°K) 1* a magnetic un i t c e l l with four Molecules per c e l l v . Above the t r ans i t ion temperature K-NiF, exhibi ts two-dinensio-

t3) * nal aotiferromagnetic o rde r v ' which has been the subject of extensive experimental and theore t ica l s t u d i e s 1 ' . In the present work a neutron diffract ion study was made of powder samples of Rb.MnCl. and Cs-MnCl,. I t trns found that as the temperature i s lowered below 180CK both compounds exhibit a ridge^ ' cha rac te r i s t i c of the two-dimensional a n t i -ferromagnet. At 57°K and 52°K respect ively, Rb-MnCl. and Ca^lnCl^. order antiferrostsg&etically in three dimensions, in iden t i ca l magnetic s t ruc ­tu res . This s t ruc ture belongs to the magnetic apace group t . m'm'm and i s , in f ac t , i den t i ca l with the magnetic s t ruc ture of KjNiF^ type* ' compounds. Legrand and Verachuerea have already proposed t h i s s t ruc ture for Cs^MnCl^ on the basis of preliminary r e su l t s .

1. BALT2, D., PLIETH, Z. Electrochem £2> 5*5 (1955) 2 . PLUHIER, R. LEGBAHD, E. , J . Phya. R a d i u s , ^ 474 (1962), and

LEGBAND, £ . , PLUHIER, R., Phys. Status Sol id! £ , 3X7 (1962) 3. B1RGENEAU, R . J . , GUGGEHHEIM, H.J . , SHXRAJffi, C , thy. Bar. L * t t * »

22, 720 (1969) 4. LINES, M.E., J . Appl. Phya. 40, 1352 (1969) 5. LEGSAND, E . , VERSCHUEREM, H., J . Phys. 25, 278 (1964)

ALLOWED NEUTRON REFLECTIONS FROM MAGNETIC LATTICES: H. Shsfoid. I t i s well kaovn that In ths c u e of the fourteen s ingle-

colored Btevala l a t t i c e s , one can always select one or more of four types of unit c a l l s . These unit ce l l s ate primitive, end-centered, body-centered and face-centered, and correspond to P, C, I , and F la t t i ces respectively. Each of these la t t i ces Is characterized in diffraction experiments by a set of reflections which i s systematically absent; or, one s-iy rather ppeak of the complementary set of ref lec-tXx.'M which i s systematically allowed. Hence any crystal of a single-colored la t t i ce can be c lass i f ied, on the basis of the systematica of the reflections i t exhibits in a diffraction experiment alone, into one or sore (depending on the choice of the unit ce l l ) of the four lat t ices P,C,l f F. In the case of the thirty-six bicolorad la t t i ces

one can always select one or more (again depending on the choice of 12 3} the unit c e l l ) of twelve types of unit c e l l s * . These unit ce l l s

exhibit different bicolored cantering translation and correspond to the following twelve bicolored la t t i ces (using the notation of

(21 OpmchcvkX and Cuccionev ) ; P, P. , ; F, F„, I, I_

Allowed neutron reflections from the twelve magnetic (bicolored) lattices*

u t t . Conditions l l s£t lng possible reflections

R e £ 1 e c t 1 0 n s u t t . Conditions l l s£t lng possible reflections ooo eee oee eoe eeo eoc oeo ooe

t / / J J J / / / * • > *

h-0 / / • / *r h»o, k«o / J *y h«o, k-o, fc"o / c h+k-e / / / / °?r h+4"«, *-o / / S h+k-o / • • / C T b+k*Op Jl«o / / F h+k«e, h+l-c, k r v e / / *r h+k»e, h+J>o, k+t-o / / i h+k+J.« / • / / h h+k+i-o / / V J

o - odd, e - even , / • allowed.

Me have classified the crystals of bicolored lattice (i.e. ferromagnetic or antiferromagnetic) into one or more of the twelve lattices, on the basis of the systematics of the reflections they exhibit in neutron diffraction experiments alone. The allowed reflections in these twelve lattices are given in Table 1,

References: 1. International Tables of X-Ray Crystallography, N.F.M. Henry and

Kathleen Lonsdale, Kynoch Press, 1952 2. OPECHOWSKI, W. and GUCCIONE, R., in Magnetic Symmetry, Magnetise,

Eds: G.T. Rodo and H. Suhl, Vol. Ila, Academic Press 1965 3. BELOV, N.V., NEROVNA, H.N. and SMIRNOVA, T.S., Soviet Phys. Cryst.

2, 3, 311 (1957)

PREPARATION AND CRYSTAL STRUCTURE OF SOME COMPOUNDS OF THE TYPE A3BXgi A. flm>*., Z.H. Kalman*, J. Makovsky, E. Ron and A. Zodkevitz.

Six new compounds, namely Cs 3FeBr g l Cs 3MnBr s, Tl,FeCl_ , Tl-CoCl, ,(Kii,)3FeClg and (NH,)3CoCl were prepared and their crystal structures determined. Cs.FeBr,- was prepared from aqueous solution while the other compounds were prepared by a molten salts technique.

All the compounds were analysed by means of powder diagrams, employing the Gulnier - de Wolf method. The crysta* systems, probable space groups and cell dimensions derived are shown in the table, along with the calculated and observed densities.

Atomic positions for cesium and ammonium salts were determined from visual estimation of intensities.

Cospound S r n - T :"* 0) (to A

z V1

T1 3 T*CL S

t»tt»- S.MXU.BM

9.SK1.00f

I.40U.D04

13.13%.01

ll.37a.01

14.71tt.0IM

4

4

4.04

3.(4

3.9610.06

J. W0.5

«,<*«, 5r (.4)'1.003 14.4*71.001 * 1.32 5.511.3

(W t )/*Clj thoblc

A M t.tllt.Oti 10.00* 10.004

lZ.U7t.00} 4 1.74 1.71(0.03

(ire^JjCocij ortko- ftai a.JUt.oa* ».914 JO.003

IZ.««I*.DM * 1.77 1.70(0.03

Habraw Unlvirtity, Jgruulitn. -

m&AKATtON AND CRYSTAL STRUCTURE OF TIMnCI^ TIFtCt3, TIC0CI3 AND *n*0$ A. Zodkwitz, J. NWcowky and Z.H. Kalmen*

The coapoamda TIMnClg, TlFaClj, TlCoCl3 and TlHiCl^ were •referee by aelt lag X1C1 with the corresponding transition aeta l dlcfelorldc im SJI evacuated ampoule. The structures and atonic positions vara determined fro* powder photographs.

All four compounds were found to have the Perovakite type atoaic arraajemeat. TlMsCl- has a cubic structure, space group Pa3a , with a • 5.025 £ . The other three compounds are hexagonal, with probable

o space group P6-ac or P6_mmc , and c e l l dimensions (in X) a - 6.976 aad c " 6.00S for the Fe compound, a - 6.907 and c * 5.981 for o r o o the Co coKpoocd and a - 6.863 and c - 5*881 for the Ni coapound. These three compounds are isoaorphous.

The cuoic and hexagonal structures are related to each other, their large ions having the d o s e -packed arrangement - either cubic or hexagonal. Two of the hexagonal compounds show pronounced basal plane stacking faul t s . The distribution of ions on the fault plane has been determined and this distribution indicates the stacking faults to be ingrown.

Utterances:

1 . Katttair, Z.H., ZODKEVITZ, A. and HAXOVSXX, J . , I s r a e l J . of Chan. £ VII (1969)

2 . ZOOKEVITZ, A . , HAKOVSKT, J . and KAIMAN, Z.H., t o be published. »

LOW TEMPERATURE ELASTICITY AND MAGNETO EL AST I CITY OF DYSPROSIUM SINGLE CRYSTALS*'); M. Roam and H. Klimktr.

The five iadepcodeat adlabatlc c l a s t i c constants of dysprosium have been detersdnedbetwean 4,2 and 300*K by aeans of an ultrasonic pulse technique at a frequency of 10 KHz. The coapressional e l a s t i c constants C ^ and C._ display characteristic anoaalies at the magnetic transition points TH <178*K) and T c <87#K). The shear constants, C^ and C^6 , are vary l i t t l e affected at X , but exhibit typical anomalies at T . The teaparature dependence of the directional compressibility K .. , parallel to the hexagonal C axis , i s qualitatively a mirror image of the perpendicular compressi­b i l i t y K o i . Both are s l ight ly affected at T ; j , but show drastic anomalies at T, . At the la t ter transition K_„ indicates a

The Uni t ing Deb ye temperature extrapolated to 0*i: umi found to bft 190*K. Anderson'svave-velocity averaging procedure van med to calculate the Debye tempera cure froa the s ingle-crystal oea3urcacac3. The e las t i c constants treasured in the present study and the reported thermal expansion data were U3ed to calculate the nagnetoelasric contribution tc the total l a t t i ce energy, applying the theoretical formulation of E. Callen and H.B. Callen. l i e energy drop at T

3 was found to be 0.71 J.ca . This drastic change in the cagrie codas t i c energy i s apparently responsible for tiie f irst-order phase transition in dysprosium at T . Reference: 1. SOSES, a. and KLEKER, K., Fnys. Rev. (Hay 1,1970)

ELASTIC AND MAGNETO ELASTIC PROPERTIES OF TERBIUM. H0LM1UM AND ERBIUM SINGLE CRYSTALS AT LOW TEMPERATURES: M. Rosen and M. KJimker.

This study Is part of a 'jider program aimed at investigating the behavior of the s ingle-crystal e l a s t i c i t y of the rare earth setaIs at low temperatures and high magnetic f i e ld s . The e l a s t i c and anelastic behavior of several heavy rare earths in polycrystall ine forq has been reported previously .

Ultrasonic Measurements on terbium, holodun, and erbius s ingle crystals in three different crystal orientations indicate a behavior analogous to that of dysprosiun (see preceding ar t i c l e ) at the magnetic transition points. Characteristic ancmalics are displayed in the temperature dependence of the e l a s t i c coef f ic ients , l inear and voluae compressibi l i t ies , and Debye temperatures. The temperature variation of the magnetic contribution to the tota l e l a s t i c energy of the crystal has been cooputed.

References: 1 . ROSEN, M., Phya . Rev. 17ft» 504 ( 1 9 6 8 ) 2 . ROSSN.H. and KLIMXEP,, l i . , K i y s . Rev . ( I n p r e s s )

ELASTIC MODULI AND ULTRASONIC ATTENUATION IN THULIUM, YTTERBIUM. AND LUTERIUM FROM 4.2 TO 300°K: M. Rosea

Tha temperature dapendanca o'f the e l a s t i c properties and ultrasonic attenuation of several polycrystal l in* rare earth metal* has been tha subject of a number of p a p a r s ( 1 ) . The prasent work la concerned with tha temperature variation of the e l a s t i c moduli, adiabatlc compressibility, Debye temperature, and u l tra-

- 6 2 •

etioa (both lMclturflul end transverse) of T»» Yb» u d 1*. A t sseerleaatal data are la tae process of analyst*. Thla wade eaaalatea aa extaasiae profraa of ultraaonlc aaaaucaaaata of the raw aartha l a eolyerystalllne fora.

lefaraacss: 1 . MSE>» H., Hiys. ear. 166, 561 (1968); Ibid 174, 504 .1966);

l b l d l f g , 540 O W ) ; ibid 181, 932 (1969)

K OF AL IN TiAl and TiAH ALLOYS: C. Korn and D. Zamir.

The elwdnoet resonance Unas in Tl + 3.5 wtt Al and in Hfl, _ 4- 3.5 vtZ Al ware Measured. Both, exhibited asyaaetry, probably dae co quadn^ole interaction. The alucinua l ine width and Knight sh i f t l a the two cases are shown in the table.

TABLE 1 Al l ine width and Knight sh i f t i n TiAl and TiAlH alloys

Alloy 4H (gauss) K (3)

Tl + 3.5 vcT. Al H a 1 7 + 3.5 wtZ Al

2.5 + . 1 5 . 7 + . 3

...

0.027 + 0.001 0.037 + 0.001

The broadening of the aluoinua l ine when hydrogen i s present i s probably due to the extra dipole-dipole contribution froa the protons. The Increase in Knight s h i f t nay be due either to a contribution of electrons to the conduction band,hy the hydrogen, or to a change in the crystal structure of the al loy. 1-Iore Measurements are in progress.

SPIN LATTICE RELAXATION TIME OF PROTONS IN URANIUM HYDRIDE: M. Burstsin and D. Zamir.

Hie spin la t t i ce relaxation tine T. of hydrogen nuclei In Utt, was Measured over the teaperature range 150 - 400*C. The ncaeureaent was carried out using a pulsed ttOt technique.

The results are shown In the graph. The appearance of a cdnlxun In tbe curve-of T^ vs . temperature i s typical of a spin relaxation aechanlsa caused by diffusion. However another iaechanisa, probably spin f l i p , which has already been obierved in other work' 1 ' , was seen too. I t la characterised by a sonotonic Increase In T, with tempera­ture, as saaa in the i n i t i a l rise of the curve. The total a pin la t t i ce

_ 7

Me 5

A ^A

i "

Fig. 1 Spin l a t t i c e relaxat ion t ine of protons in UH

as a function of temperature

relaxation time can be wri t ten: •=— =• •=— •*• •=— - The diffusion T l T l s .f . T u

constants can be calculated frtra th is expression.

Reference: 1. KUZHITZ, H., Thesis, Tecunion-Israel I n s t i t u t e of Technology (1967)

NMR STUDY OF HYDROGEN DIFFUSION IN THE THREE PHASES OF THE TITANIUM-HYDROGEN SYSTEM*1*: C Kom and D. Zamir.

An NHK pulse technique at 19.00 MHz was used to measure th* proton spin l a t t i c e relaxation time T, as a function of temperature In the range 25° - S00°C for a aeries of titanium hydride samples in the a, I and y phase*.

The relaxation mechanism in the a and y phases was governed primarily by hydrogen diffusion over most of the temperature rang*. The diffualonal activation energy In the y phase was found to be constant with respect to the hydrogen concentration, having a value of 11.7 + 0.4 kcal/aola, and the jump attempt frequency was propor­tional to the Available local vacancies. Evidence was found for a uniform distribution of hydrogen, la the y phase when the ratio of hydrogen to titanium atoms, i , Is greater than l„6,vhl le clustering takes place at lower ratioe.

The (T.) data showed that the. low temperature y phase transltlom at a hydrogen concentration of x - 1.6 was related to the

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electronic structure. Th* conduction electrons were the primary c — t of relaxation l a the y phase near rooa taaperature, and the coatrlbatioa of th is aechaalsa to the relaxation rate Increased with increase la hydrofea cooceatration. (Tj) T ranged fro* 190 + 4 sec.°K to 62.5 + 2 see.°K aa x Increased froa 1.55 to 1.90.

The a + y , T phase boundary was found between 25°C and 100°C. Diffnsloa parameter* ware aeasured for the a phase, and the gradual transition froa the a + y Co the y region was observed. The transition froa the a + y to the B phase displayed a heating-cooling hysteresis e f fect . T, for the 6 phase of TiB^ ? s near 450°C was governed aa£sly by the conduction electrons and a value of ( T ^ T - 5 5 + 5 sec. D K was found.

Reference: 1. K 0 « , C. and ZAKIK, D. J. Phys. Che*, of So l ids , 31,489 (1970)

A METHOD FOR PRECISE DETERMINATION OF NMR LINE CENTERS USING ANALOG FOURIER TRANSFORMS: U. Et-Bantny.

In connection with the laeasuretaent of the Knight sh i f t of broad i££R l ines in aetals* the problea arises of determining the precise center of the resonance l i n e s .

Working in pulsed XMR, one gets the free-induction-decay (FID} l i n e shape, which i s a function in the tine doaain. For exanple, a Lorentzian FID w i l l be given by

S(t) - exp(-t /T 2 ) (1)

at exact resonance. With phase-coherent detection the general FID shape would be

f ( t ) - exp(~t/T 2 )(cosut.cos0 + s inwf s in0] (2)

where 0 i s the phase eagle between reference and signal , and u - y(H-Uo) i s the deviation froa the resonance f ie ld in frequency units, with y being the gyroaagnetic ratio of the nucleus.

The FID i s Integrated in the t iae doaain by a pulsed integrator (boxcar). I f the integration were Ideal, i . e . froa t - 0 to t • « , one should get the following Fourier cransforas:

lor # - 0

7 -t/T« ( I / v ' , W - e" t / T 2cos»tdt - -* ^ (3)

. { «2+U/T2)2

vnic!i i s the absorption l ine.

For t - J

<*)

I t Is readily seen that I t i s ouch easier expert rr-entally to find the center of the l ine by looking for the zero of the dispersion than by looking for the oaximua of the absorption. In the f i r s t case the shi f t froa zero i s linear in u whereas in the second case the shift from the maxicua value i s a second-order effect in a .

Tn practice Che integration la the t ice detain i s fro= s co A , where a i s the recovery tine (or dc d tjr-g) of the pulse system after transmission, and A r the upper l i n i t of integration, cannot be too big since the output of analog integration i s proaortionai to 1/A. Then the "effective"dispersion line-shape vould be;

A r

2*(u) - f e " t / T 2 s i n u t d t

" a' T 2Icoswi +(l/uX 2)sinua]-e"'* / T 2[cos^l.4-(l/aT,)sin«Al I (5)

The function F,"(o>) differs fron F,(u) in the following respects;

a) There i s high-frequency oodulatioa of relative amplitude * " * and cycle 2«/A (In frequency units) . This codulation becoees negligible when A » f, .

b) There ia "low-frequency" modulation of cycle 2»/a. '.lien a < T_ , the f i r s t zero of this modulation w i l l f a l l outside the line-width. Generally I t w i l l have the shape shoim in Fig. 1.

However, the important point Is that there i s no shi f t in the position of the zero.

Zn practice the assumption 9 » »/2 i s not exactly fu l f i l l ed mad there Is a s l ight Mixture of absorption into the dispersion and*. This admixture bring* about an effect ive shi f t of t i e center of tut l i n e . I t can easi ly be shown that a few cycles of adjusting $ and H define the canter of the l ine with a precision of 2f of the l ine width» where 1/f ia the •Ignal-to-iniaa ratio of the Masured Una. This coapares favourably with the preciaion of only l/t obtained by the usual •etliod of looking at the absorption node.

- 6 6 -

Fig. 1 Real and "effective" dispersion l ine (schematic)

The Method described i s a general one for defining l ine centers with high precision. I t has been applied to the measurement of small changes in the Knight s h i f t of copper up to the nelting-point and in

References: 1. CUtt , W.G., Eev. E d . Instr . 35, 316 (1964) 2. EL-HMAMlt, D. and ZAMIE, D., Colloque Ampere XV, North-Holland

Publishing Co., Aasterdaa, 1969 3 . EL-HANA.TY, D. and ZAMR, u . , Fliys. l e v . 183. 809 (I960)

DIFFUSION OF COPPER AND ZINC IN PRASEODYMIUM: M.P. DarM.

Diffusion i t u d l u on noble metal aolutca In group III-B and IV-B • s ta l e have shown that the controlling aiecluraiaa) for solute dlffuaion l a aot the uaual vacancy Mechanism' 1 5. I t la tha widely held view that these solute* diffuse sa I n t e r s t i t i a l ! in the solvent host natal l a t t i c e . The striking feature of thia diffusion aechaniea Is the high diffualvity of the solute, as compared with the se l f -di f fusion coefficient of the solvent ae ta l . Following recent atudlea I t appeara that a a la i iar diffusion aechanlaa prevails i n rare earth neta ls* 2 ^,

la order to gain further insight into the energetics of this diffusion •echanlsa, the dlffueivity of 6 5 Zn waa meaaurad In both phases of praaaoayaltaa, using the thin layer sectioning technique. The reaulta can ha expressed by D - 0.64 exp(-270OO/RT) and D - 0.18 exp<-24500/RT) cai / sac . I s bec and dhep prasaodyaiust respectively. These values are

higher by several orders of magnitude than the self-diffusion coefficient3 of praseodymium. Preliminary ceasureoents of the so lu te diffuslvicy of

Cu yielded values higher by an order of magnitude Chan chose of zinc. An increase of solute dlffusivlcy with decrease of so lu te valency i s contrary to the expectations of a vacancy diffusion mechanisa, but Is in

References: 1. PETERSON, H.L., in "Solid State Physics" 22, 409, Eds. F. Seit=.

D, Turobull, and H. Chrenreich, Academic Press , N.Y. (196iJ) ,p.409 2. DARIEL, M.P., EREZ, G. and SCHMIDT, G.H.J., J* Appl. Fays. 40,

2746 (1969) 3. :01LEK, J .H. , Phys. Rev. 181. 1095 (1969)

DIFFUSION OF COBALT IN BETA-URANIUM^: M P . Dariei. M. Blumenfeld and G. Kimmel.

The extreoely high d i f fus iv i t i e s of the ircn-gronp solutes in ganaa-uranima1 , * suggest tha t t he i r diffusion mechanlsn say be different front that of the sel f -di f fusion of uranium. In order to study th i s problem further , the solu te diffusion of cobalt in beta-uranium was measured, using the thin- layer sect ioning technique. The resu l t s can be expressed by D - 1.54 * 1 0 - 2 exp(-27450/RT) c a 2 / s e c . This i s about three orders of magnitude higher than the se l f -diffusion coeff icient of beta-uranium.. A comparison of these r e su l t s with those found i n similar-systems, i . e . thallium and praseodymium, suggests t ha t cobalt may diffuse by swans of the combined subs t i tu t iona l* i n t e r s t i t i a l mechanism.

References: 1. DARIEL, H.P. , BLUMENFKLD. H. and KMGL, G., J . Appl. Phys.

March 1970 2. PETERSON, II.L. and ROIHHAN, S .J . , Phys. Rev. 136A. 842 (1964)

OXYGEN SELF DIFFUSION IN U O j : Z. Haderi, M. Kroupp and I. Volfaon*

It is of great practical importance to know the diffusion coef­ficients, and activation energy of diffusion, of oxygen in UO„. An

IS 1$ experimental technique baaed on the nuclear reaction 0 (P»Y) F has been developed , and was used to determine the diffusion profile at various temperatures*

The diffusion couple consisted of two TO- pellets, one of which was BOX enriched with 0. The pellets were pressed and subjected to thermal annealing for various times, after which they were separated

VWiman InKltutt of ScknM, Rthovoth.

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jad t s * surface of eb« utiearlehad p«ll*t analysed for 0 content. The eaalysis was carried out oo the basis of ttw above nuclear reaction, uelac the Tarn de Craaf accelerator at the Ueisnan Inst i tute . The surface of toe pe l le t was then pollened with a special apparatus able to triad to a precision of one aicrou, and again subjected to the saae reaction.

ftit-imtnh the aboTe polishing technique was quite accurate, I t was s t i l l not as good as sectioning, and therefore sectioning was • f inal ly adopted. The diffusion coeff ic ients found are given in the table.

TABLE 1 Diffusion coeff icients of oxygen in VO^

leap. C O D (en2 sec"1)

1425 ± 5 1225 ± 5 1025 ± 5 9025 ± 5

(7.1 ± 0.2) x 10" 1 0

(3.7 ± 0.2) x 10" 1 0

(2.3 ± 0.1) x 10" 1 2

(1.6 ± 0.1) x-10" 1 2

KINETICS AND MECHANISM OF THE AGE-HARDENING PROCESS IN ALUMINIUM ALLOYS: Y. Gefsn and M. Rosen.

Hi* kinetics and mechanism of the formation of Guinier-Preston zones and of incoherent precipitates ere beins investigated by Means of ultrasonic attenuation, e l ec tr ica l r e s i s t i v i ty and hardness Maeurements. Xhese experimental Mthods y i e l d , Independently, important information on the extent to which the precipitates ex is t and their relative dimensions.

Specimens of alunluum-rich a l loys , with various additions of zinc, s i lver and gold,have been prepared in the form of s ingle cryatale in different orientations. The ef fect of composition, crystal orientation end ege-hardening treatment procedure ere being measured at ultrasonic frequencies in the range 1 - 3 0 0 m i . These results , aa well es those of the e lectr ica l res i s t iv i ty and hsrdness measurements w i l l be analysed in terms of the recent theories of the age-herdenlng mechanisms.

RESEARCH ON U3SJ: G. Kim me I, A. Romer, E. Amir, J. Shalev, J. Levy and A. Bar-Or.

U_Si i s considered a promising alloy for fuel elecents in pover reactors operating with na tura l uraniun and ooderated by high pressure heavy water. This mater ial i s now being studied a t several centers .

Some casts of U-Si were prepared in our laboratory and the k inet ics of the per i tec to id transformation U-Si, + 3U -»• 2 U"3Si was s tudied . This transformation, which converts the al loy to the su i t ab le phase,was thought to be s luggish, taking 6 days a t 800*C under v a c u u a " ' , Sanples were annealed in a wide range of temperatures, from 620*C up to 920°C, and su i tab le metallographir. procedures were developed m order to dist inguish more eas i ly among the various phases on the surface. Quantitative analysis was carried out and i t seeos that the t ine to complete the transformation i s only 24 hours a t 800"C. The width of the U„Si intermediate layer was measured as a function of time and tempera­tu re , and was found to be given by

f 50000) 0.85 exp I =^-I f 50000]

r R TJ

where x i s the width in 03, t the time in seconds and T the annealing tenperature in *K. The temperature i s U n i t e d to S20°C i f the alloy contains some hundreds ppm of carbon.

The transformation i s i l l u s t r a t e d i n the f igure .

Fig. 1 l e f t - «s c a s t ; center -

tranaformation; r igh t - complete transformation

References: 1. AECL-2874, 1967 2. WILKINSON, W.D., Uranium Metallurgy, Vol.2, Inttrscienct, 1962,

pp.1109-1126

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THE EFFECT OF HYDROGEN ON CRACKING IN IRRADIATED URANIUM1^: H. Mrthiat, Z. Uvne and A. Bar-Or.

ID spite of the advantageous features of metallic nuclear fuel , namely high density and good thermal properties, i t s use i s restricted because of dimensional ins tab i l i ty , due to irradiation growth and swelling. Research with high purity uranium has shown that, contrary to earl ier suggestions, irradiation-induced f iss ion gas i s not a significant cause of swelling unt i l well above 600"C, while extensive swelling at lower temperatures i s due to cavitation, which is- not associated witJi fission gases. This cavitation swelling was partly

(21 related to Irradiation growth effects and intergranular creep cavitation in the range 400-500*C, but the exact mechanisms responsible

(2) a or the phenomena observed between 500-600 C are not understood.

Fig. 1 Cracks in irradiated coarse Fig, 2 Cracks associated with grained uranium, ordinary l ight clusters of preferentially oriented (x 100) hydrides in irradiated coarse

grained uranium; polarized l ight <x 200)

En the present work an attempt was made to study the effects of hydrogen on cracking In p i l e irradiated uranium. Since hydrogen i s usually present in nuclear uranium i t was believed that even small amounts might accelerate crack formation or cavi t ies . Specimens of U - 0.1 /o Cr were prepared with grain s ires of 0.2 and 1.5 mm and hydrogen content in the range 1 to 3 ppm. The aluminium clad specimens were Irradiated up to 500 ibit)/'£t the temperature reaching 450*C at the center of the specimen and 150'C on the surface. Audio­graphs showed that the specis^ns with the large grains-(1.5 ran.) were significantly distorted, displaying local changes of diameter

- 71 -

as well as strong wrinkling . No such deformations were observed in specimens with small grain s ize (0.2 mm). Discs of 5 am thickness were cut from the specimens and examined under the nicroacope. The large grain sized specimens' revealed severe cracking ( f ig . 1) in the core region, in addition to microscopic d i s to r t ion . Examination with polarized l i gh t showed that almost a l l these cracks were associated with uranium hydrides (Fig- 2 ) . The l a t t e r were easi ly ident if ied by thei r shape and by the white halo around them. Clusters of re la t ive ly large preferent ial ly oriented hydrides ( f ig . 2) were present in the core and intermediate regions, but not in the rim region. The fine grained specimens showed almost no cracking, although qui te large uranium hydrides were present in the core region.

I t i s concluded that i r rad ia t ion growth i s responsible for the profound change in dimensions found in the specimens with coarse grain. In addition,hydride cracks contribute to this change. Hydride cracks and the i t concentration in the center of the specimens are a t t r ibuted to the fact that the hydrogen tends to migrate towards the center where i t s so lubi l i ty i s higher due to the higher temperature; on thermal cycling, hydrides al ternately precipi ta te and dissolve, each precipi ­tat ion causing cracks in the uranium made b r i t t l e by i r r ad i a t i on . I t i s suggested that in power reactors thermal cycling gives r i s e to periodical dissociation and redis t r ibut ion of uranium hydrides which may augment swelling in addition to cavitat ion and bubble formation, the dimensions of the hydride cracks depend on the thermal cycling ra te and amplitude, hydrogen content, temperature and the i r rad ia t ion t'ose.

References: 1. MATHIAS, H., LIME, Z. and BAK.-0R, A., In tern . Conf. on Relation

between Properties and Microotructure, Haifa, July 1969 2. LEGGET, R.D., BIERLEIN, T.K,, 1IASTEL, B. and TAYLOR, H:A., Radiation

Effects, tf.B. Sfieely, I'd., Proc. Conf. Met. Soc. A&E, Vol.37, p.303 (1965), Gordon and Breach, 1967

COMPOSITE MATERIALS BY CHEMICAL PLATING*1': M. Ryndzumki Mid A. Bar-Or. The growing need for new [materials with a combination of properties

not found in c l a s s i ca l homogeneous materials has stimulated widespread research on composite materials . We have prepared and examined sow composite materials sui table for nuclear fuels and other purposes.

Hie good s t a b i l i t y of U0, under i r r ad ia t ion has established th is material as the most important nuclear fuel* I t s disadvantage however i s i t s poor thermal transfer propert ies . To improve these the U0„

- 7 2 -

cam t* disperses l a a Metallic u t r l x * ' , which la usually done by slaterlag DO, vita aetal l ic powders. However, this acthod Is i a -coawaiMt when thim layers are required. Several studies on electro-eapositloa • • a. method for imbedding ceramic powders ware recently psbllssss 3,*) Following this trend, we examined the chemical nickel platlag process for forming cosposltes of 00, and other ceramic powders. Ibe »—«•>— process for slectroless nickel plating was chosen for this pezposc. Seine non-electrolytic, this pxocees should uniformly cover t ie irregular shapes of the caraadc particles to be imbedded. The plating solution contained: nickel sulphate 48g/l , sodium acetate 10 g /1 , sodium hypopbosphate 10 g /1 . Ihe pB was 6.4 - 6.5 and the temperature 90 - 92"C. Figure 1 shows t h e composite ach ieved by

1^+ddfnt DO, particles in the plating. Other powders successfully imbedded f-wlndf 3h0., . the latter being of interest because of i t s special lubricating properties (see Fig. 2 ) .

I t was found that the hardness of the plating could be increased in three wave: a) by Increasing the content of the imbedded powder, b) by varying the type of powder, c) by annealing at the appropriate temperature (see Fig, 3) . I t Is seen from Fig. 3~tfcat the hardness reaches a maximum at an annealing temperature of 400*C, both in the pure plating and in the coapoeltes. lb* hardening of the pure plating i s connected with the precipitation of Hi.P * ^. since the hardening curve* of the composite plating run above, vet almost parallel, to that of the electro!*** plating. I t to suggested that th* two hardening

« 2 particle* imfcedded Is alsctrolass nickel plating (x 500)

«g. MoS, Imbedded in electro-less nickel plating (x 150)

• 7 3 •

mechanisms. I.e. that caused by dispersion of powders and by precipi­tation of Ni.P, are Independent of each other. It io also suggested that the heat treatment does not affect coherency between the imbedded powders and the plating.

In addition to the use of the above process in the product ten of special fuels, two other major applications are suggested, naaely improvement of the wear properties of metallic surfaces, and Improve­ment of the lubrication quality of various surfaces. Samples of electroless and composite plating were tested for wear. The samples were vibrated on diamond powdered cloth for various times and the loss of weight measured. The results are shown in fig. 4.

1 alBCIiatsu Ni ploiiag 2 •I*ctrot«i» Ni picting . Al^Cj 3 *I*cticl«u H' ptetung . ThOj

Fig, 3 Uardness of nickel plating composites after annealing for one hour at various temperatures

Fig. 4 Hear properties of nickel plating composites

itiMDZUNSKI, M. and BAR-OR, A., Intern. Conf. on Quantitative Halation Between Properties and Kicrostrueture of Metals, Haifa, July 1969 WEBER, C.E. and UIRSCi:, fi.H., Dispersion Type Fuel Elements, Progress in Nuclear Energy Series, Vol.1, p.532 (1956) SAUTTER, F.K., J. Eltctrochem. Soc. t U2. 557 (1963)' VEST, C.E. and BAZZARRE, D.F., Metal Finishing 65, 52 (1967) GOLDEHSTEIN, A.W., ROSTOKER, K., SCHOSliERGEK, F. and GUTZEIT, C.» J. Blectrochcm. Soc. 104. 104 (1957)

PURE AND APPLIED MATHEMATICS

The work summarized In this section reflects some of the mathematical studies carried out during the past year. The topics are mainly concerned with matrix and non-associative algebra, analysis, and applications in chemical physics.

ON ALGEBRAS CONNECTED TO LIE AND ASSOCIATIVA ALGEBRAS ' - '

The b i l inear nap u , (u: V * y •* V), which far any x.y.z ir- the vector apace V sa t i s f i e s

u(u(x,y).z} - u(x.u(y.s)} - u [_{y ,x) ,z) + . ( y . a d . i ) } - 0 (l)

The foil c-i rig if u(x,y) satisfies Eq.(l) and

fl(z.y) " u(z.y) - u(y,z). then C defines a structure of a Lie algebra. For the special case when u Is associative (Eq.(l) is trivially satisfied) it is well known that i defines a structure of a Lie algebra.

We call a non-associative algebra, which generalizes an associa­tive algebra in the above sense, a GV (Generalized Vinberg) algebra, i.e. the algebra of the connutators in a GV algebra is a Lie algebra. Now we define

xy = u(x,y) (x.y.z) - u(u(x,y),z) - u[x,u(>»z)) V^x.y.z) - (x.y.z) - (y,x,2) Vr(x,y,z) = (x.y.z) - <x,z,y) vg(x,y,z) - (x.y.z) - (z.y.x) Jtx.y.z) - (x.y.z) + (y.z.x) + (z.x.y) - (x.z.y) - (y.x.z) -(z.y.x)

and obtain the following theorem;

The algebra in which one of the Identities V (x.y.z) - 0, Vr(x,y,z) - 0, Vs(x,y,2) - 0 or J(x.y.z) - 0 is valid for an> r.,y,z,te a GV algebra.

We call these algebras respectively V., V , V and Jacohy algebras. V- is the Vinberg algebra defined by Eq.(l) and V is the anti-flexible algebra. The identity J(x,y,z) • 0 is equivalent to the Jacoby identity.

Two algebras are defined as quasiequlvalent if they have the aaae set of elements, the sane operation of addition, and the opera­tion of Multiplication u of one algebra la related to the multipli­cation 0 of the other by fl(x,y) - au(x,y) + Bu(y,x), where

-78 -associative algaerae a n belne. studied In the light of this concept •f ejiasletelvelaace. •efsi 1. lXJDnWIS, A. , Mew Archief Toor Wlsfcimde (3) 17, 17 (1969) 2. VTMOG, F.B.. Irjns. Moscow Math. Soc. (English translation)

12, 340 (19*3) 3 . u m , A.A., Fortnealiae Kerh. jl , 23 (1949)

THE FOUfEH OF A MATHIX AND THE GENERALIZED LUCAS POLYMONIALS: Y. Hamad.

Aa a x n astr ix X defines the functions L ^ ( ^ * n ) when x5 i s expressed in toe fora

f-l.tfr* (1)

ufamre •-,.,*, f are the coefficients of the characteristic equation

if. I (-«k-\x-k

fc-1 The function L*5 Is called the generalized Lucas polynomial of degree n-r+1. Explicit formulas for Lit and tables for the general ized Lucas polynomials of degree 1-5 for n"3,4 and 5 were recently

In the present work the generalized Lucas polynomial of degree r Is given explicitly, for any r and n, si a determinant of order r or as a ratio of two determinant* of order n. (The elements of the determinants are expressed as functions of *>, • _ ) .

Reference: 1. BARAXAT, R. and BASKAil, E. , J. Hath. Phys. 10. 1474 (1969)

CAYLEY-HAMILTON IDENTITIES FOR MATRICES WITH NON-ASSOCIATIVE

ELEMENTS: Y. Itamtd The Cayley-Bamilton ident i t i e s (CU.I . ) for matrices whoae

elements are members of an associative non-commutative ring were previously developed and appl ied^ 1 - 3 *. An extension for the case where the elesmaCa of the matrix are members of a non-aaioclative ring i s given here.

A multiplication of n factors i i defined by the bracketed product of these n factors. The get of monomials obtained by complete bracketing of a monomial i s the aet of a l l different

bracketed products obtained vliilc prcservi&g the order of the

factors. For exanple, complete bracketing of the oonomial syr. gives

the set : (xy)z, x(yz). Let Bo, denote the sua of aona=ia.L<i obtained

by complete bracketing of the nonomial m,. The new (extended) C.H.I.

are I Bo, - 0, if the old C.H.I. ' are written in the fora 7 a, - 0. i 1 , i i

To solve • natural problem chat occurs in working with these csw

ident i t ies , we introduced the n-product associative r ings, i . e .

non-associative rings in which the product of n factors is

indepandent of bracketing. The n-product associative rings have been (4)

further studied by Boers Reference: 1. LEHRER, Y., Bull. Res. Council, Israel 5A, 197 (1956) 2. GOLDBERG, H., and LEHRER ILAHED, T. . J . :iath. Phys. ^ 501 (1963) 3. ILaMED, L.Y., in Racali Memorial Volume, Spectroscopic and Group

Theoretical Ilethod* in Physics, Kerch Holland Publ. Co., 1968, p.125 4. BOERS, A.H., Indag. Hath. 31, 113 (1969).

ON THE KOROVKIN SUMMABILITY OPERATOR FOR DOUBLE FOURIER SERIES 1 1': I. Aviram.

Korovkin's theorems1 for the s o l u b i l i t y of Fourier series in

one variable were extended to double Fourier ser ies .

Define Korovkln's kernel in two variables by

u—m v—n

of real numbers, with »,n • 1,2,...; u • 0,1,2,..., •; \» - 0,1,2,..., n Let f(x,y) be a continuous (2K,2w) doubly periodic function. If K/J* J satisfies the following conditions:

lim T„J " 1 f o r « ny u» y» * B l l(»»y) * ° for any x.y £[-»,+«], m,n •

then

11M o m n (f; x,y) - f(x»y) uniformly In x and y . m,n + ••

+* +ir Here o ^ (f; x,y) - w 1 / 2 J f f(s,c) K^Cs-x.t-y^sdt.

IT W

The pointwlse error is bounded by the following expression

I <ct_;0 - |e_(fi«,y) - £(i.y)| « U1(Si)[l + - ^ (1 - T { S ' I I ) ) 1 / 2 ]

where U| aad u 2 are the partial Moduli of continuity of £(k,y) and £1,62 > 0.

Moreover, it can be shown that

K^Cx,?) - *JM KnCy),

t M . p W p W ,

where K4(u) i s Koravkin's kernel for the susaability operator o, (f;u) in one variable and P^ i s the corresponding matrix of damping coeff icients.

1. AVIUM, I . , SIAM J.of Appl.Math.(in press) 2. KDKWUN, P.P. , Linear Operators and Aoproxiaation Theory, Delhi,

Hind. Publ. Co., 1960

CONSTRUCTION OF THE FEJER KERNEL FROM A MAXIMUM PRINCIPLE^: I. Avkam. '

The following l e w * la proved. Let F [ n ; C t n ) ] be the class of real even trigonometric polynomials F (x) of degree n defined on the closed interval [ - * , * * ] :

*„w - 1 +1 c i 0 ) » » ™. v-1

subject to conditions F ( x ) * 0 for every x e [-ir, 4ir] f and c ^ - 1 • n 0 Then

w x [ F _ ( 0 ) ] - F * (0) , F " • n

where FQ (x) Is the Fejer polynomial (kernel) defined by

1. AVIUM, I . , SUM J.of Appl.ttoth.(ln p r c n )

AN EXPANSION THEOREM FOR PRODUCTS OF GENERALIZED HERMITE-GAUSSlAN FUNCTIONS*1*: J. Katriel.

An expansion theorem was derived for products of two generalized Hermite-Gauaslan functions on two arbitrary centers in tenas of an orthogonal but otherwise arbitrary set of Kermite functions. Sooe special cases vere considered, as well as the use of the results for the evaluation of a l l Che matrix elements necessary in nolecular calculations.

Reference; 1. KATRIEL, J . , Chem. Phys. Letters 3_, 624 (1969)

MOLECULAR INTEGRALS OVER GENERALIZED HERMITE-GAUSSIAN FUNCTIONS 0 1 : J. Katriel and G. Adam..

A generalized form of the Hermite-Gaussian functions was considered for molecular calculations. Explicit analytical formula* were obtained for the necessary integrals.

Reference: 1. KATRIEL, J. and ADAH, G., J. Chem. Phys. 51, 3709 (1969)

MOLECULAR INTEGRALS OVER GAUSSIAN FUNCTIONS*1); J. Katriel.

Explicit analytical expressions for the Molecular Integrals over Gaussian and el l ipsoidal Gaussian functions were derived.

Reference: 1. KATRIEL, J . , Chem. Phys. Letters ,4, 397 (1969)

PHYSICAL REALIZATION OF NON-COMPACT DYNAMICAL SYMMETRIES*'*: J. Katriel and G. Adam.

The dynamical symmetry of a charged apinleas harmonic osci l lator in a constant magnetic fi«ld was identified. For low f ie lds I t la SU(3), for high f ie lds SU(2,1) and for a certain definite intermediate f ie ld SU(2)® H .

Reference; 1. KATRIEL, J. and ADAM, G. Phya. Rev. Letters Q> 1310 (1969)

- 82 -

A SYSTEM WITH INFINITELY DEGENERATE BOUND STATES*1); J. K i t r i t l and

G. Astern-I t was •bown that an anisotropic harmonic osci l lator In a

constant magnetic f i e ld , can, with- a certain choice of parameters, constitute a system with an infinite number of equally spaced, Infinitely degenerate bound states .

Reference: KATRIEl, J. and ADAM, G., Am. J. Phys. ,37, 565 (1969)

ON THE USE OF SECOND QUANTIZATION FOR THE CALCULATION OF TWO-CENTRE HARMONIC OSCILLATOR INTEGRALS^: J- KatrtV and G. Adam.

Second quantization of the harmonic osci l lator was used to derive two-centre overlap, dipole moment and kinetic energy integrals.

Reference: 1. KAIBJEL, J. and ADAM, C , J . Phys* £ 3,13 (1970)

A SIMPLE SOLUTION OF THE LINEAR POTENTIAL PROBLEM 1^: J. Katriel and G. Adam.

the problem of the linear potential was solved with the aid of a unitary transformation. I t was shown that the energy eigenvalues are the zeroes of Che Airy function and that there i s good agreement with the eigenvalues obtained by the 1-7.K.B. approximation.

Reference: 1. KATaiEL, J. and AUAli, G., Physica 43, 546 (1969)

ANALYSIS OF VARIANCE BY THE RANGE METHOD: M. Gazith.

Analysis of variance i s a technique employed for the evaluation and testing of e f fects , and interactions of e f fec t s , on a measurable dependent variable, when several Independent variables operate. The independent variable* are usually assigned leve ls , not numerical values, and the calculations ate based on s t a t i s t i c a l principles, with the results having certainties of less than 100 percent. An example la the irradiation of potatoes. The independent variables are storage time, exposure periods at room temperature, and irra­diation ot lack of i t . The variables measured arc the concentra­tions of the potato components, e.g. starch, sugar, sol id material, vitamia C» *te . Analysis of variance i s essential for data where

- 83 -no mathematical or empirical functional connection between the independent and dependent variables can be establ ished. For a

variable with several levels , a graphical representation of the experimental resul ts can be made and compared with the resu l t s calculated by the technique of analysis of variance. For a three-factor experiment with repl icat ion, the computations for the analysis of variance are extensive since the squares of the data and various sums of data ace required. A computer prograa i s thus desirable and such programs are available" i .

A short cut for the analysis of variance was developed using the range ' instead of the sum of squares for the calculation of variances. The range is defined as die difference between the highest and lowest values of the data: R » x . . - x . . , and i t can be expressed s t a t i s t i c a l l y in teras of o , the population standard

(3) deviation : R = a a , where n I s the number of data values or n levels and a *=» nf/T/n . The sample standard deviation, s , can be

* (4) expressed s t a t i s t i c a l l y v in terms of o: s = P ^ . where S i s a constant. Hence — a — * Y , or

n

a = E/Y„

- JZ n - 2, 10

i JOti ii - 4, 5, 6, 7

n - 3, 8, 9

The value of y can also be obtained from theoret ical values of n a and 3 * n n

2 2 I t follows that the variance i s simply V « s • (R/y ) instead

2 CEx.)2 of [ Ex, ] / (n-1). The accuracy of this method is very high when n < 5 » and approaches 85% as n -*• 10 »

For a three-factor experiment with replication, where the factors are T, Q, I with a nuwber of levels t, q, i, respectively! and a number of replications r , the equations giving the variance for the main effects V_, V Q, V., and experimental error due to repli­cation, V , are as follows:

. -L. p i . v . JL p | . v . _L. £2. i<ir k ' Q tir Y J ' VI tqt

J _ J " y t q l

- 84 -

•kare j _ , L, »_ ara tka raaeae of tha appropriate SUM of data and ^ l i <k> raaaa i s a sat of W f U a u data.

Stasia asaraaeleaa (or tM lateractioa w l a a c a a V „ , V H > V Q I

aad » _ . n n derived aloaf with, tka above aquatloas. These vara faaad ta a* very a c c e n t s , except i n the caa« of * j n j . <*ea V™ la r a i l sad a * 5 . The iaaccuracy In tba l a t t e r casa la due to tha fact that tha eaaatioa for » W I involves differencial.. Toe caata y i e l d ta* aaaa anaMc-rs aa the longer aun-of-squaree aathod. No addi~ tlnaal tablaa of data or calculated results ara necessary and the ralraliHoaa caa be dona aennally in. a fraction o f tha t laa required for the conventional aethod.

lafaraaoaar 1. R K , K.C., Tba Design and Analysis of Sc i en t i f i c Experiments,

addlaoa-Wealer, 1367 2 . aatBt, E.L., A Statist ical . Haauel for Oiealsts , Academic ?ress,1960 3 . BOBOriT, C.A. aad HtaHELDI, S .L . , S t a t i s t i c a l Analysis In Chenistry

aed the Oataical Industry, J . Wiley, X.T., 1954, p . 165 « . m m . A., S t a t i s t i c a l Xhaory u i t h Engineerllig Applications, J . Wiley,

» . * . . 1952, P-30&

- 85 -

HIGH ENERGY AND NUCLEAR CHEMISTRY

Research activities in this field are directed along three main avenues - +he stud? of fisaioa and the properties of fiaslca produced nuclides, the study of high energy chemical reactions, e=d the development of nuclear and related Methods of analysis.

The fission research program is concentrated mainly around the SOLIS isotope separator, vhich is being used for the measurement of independent Isotopic yields of various elements and for the study of nuclear properties of very ahort-lived nuclides fax from the stability line. Several new isotopes have been identified and studied.

In the high energy chemical reactions program, studies with nuclear reaction recoils were continued, and the use of accelerated beam techniques is now being introduced. A study of the charge exchange processes in the ion source of a quadrupol« mass spectrometer has been initiated. Construction of a chemical beam reaction analyser is Hearing completion* This apparatus Is designed for the study of cross sections with beams of ions, atoms and molecules at kinetic energies above 10 eV.

The analytical program is concerned with development and application of activation analysis and X-ray fluorescence.

DERIVATION OF THE AVERAGE DECD-V?OSIDO.\ PROBABILITY r~ H37 v r j t ^ i ^ DURING MODERATION'": M. Bacr and S. Amict

••uneculcs torni>d by hot reactions t;i giuccm ccdli* arc '.z c c : u i : cases highly excited t ra iu la t lonnl ly . Such colcculca cjy c i t - c r ic-m tiielr energy to the surroundings or dtsaociate so fora oumr d^e-stct-ij. L ox undetectable products. In order to extract froa the experUi^cral data information concerning the fate of these isaleculea the kinet ic

C 3) theory of Estrup and Wolfgang*"' has been tzodified. T-.KS taa well known formula

P - 1 - exp-(£l) CD

where P i s the yield of the hot react ion, f the fraction or coll isions t!ie hot ato= calces with the reactants , a the average logarithnic energy decxenent and I the reactivi ty in tegra l , i s replaced by the formula :

P « 1 - exp- - I (1 - fJ - (l-E)J ) C-)

where J and J are the average probabil i t ies for decc^poaicioa of the hot products due to col l is ions with tha reactant a=d Lie moderator respect ively. Substituting x for ( l - f ) /£ one can s'c.o^„ following algebraic rearrangements, that ;

. J - J ^ - l 1_ a r l " 1+s 1-J J - r n f l + - ± - " M C3)

where a and a a r e t h e a v e r a g e l o g a r i t h m i c ene rgy l o s s e s due

t o c o l l i s i o n s of t h e h o t atom u i t n t h e r e a c t a n t and t h e

mode ra to r r e s p e c t i v e l y . In t h e a s y m p t o t i c c a s e where x -* °> ff * 0)

t h e above f u n c t i o n becomes a s t r a i g h t l i n e w i t h I n t e r c e p t

a / I C 1 - J ) and s l o p e o / I ( l - J ) . r r ran

P e r f o r m i n g t h e e x p e r i m e n t s w i t h two d i f f e r e n t m o d e r a t o r s , one

d e r i v e s , by t a k i n g t h e r a t i o of the two s l o p e s , t h a t

a / a - ( 1 - J ) / ( W ) mj ni2 raj' raj

Prom theoretical considerations we found that (1.4,5)

a /a - (1-8 )/(l-6 ) (4) °1 m 2 1 2

2 where p. « [(m-M.)/(m+>i.)] » and a and H. are the masses of the hot atom and the two different moderators. Using this formula one gees the value of (1-J )/(l-J )• From qualitative srguoenta given else-

(1 6 7) m 2 * 2

where * * it can be shown that with helium as a moderator the

- M -

m m t sir—m nsltios. airobsblUty of th« hat molecules l i pract lcs l ly s e n . A M uktac • heavy i M i t gas (Ar, Kr, or X*) as ths second moderator C M obtain* the value of J^ far chic moderator.

As M SXamsl* w« Created ChC » K U l »

< 3 + + * e r * Ctt

t0Wr + B

semefe* by Sack and Cordwer . The y ie lds wcr« measured one* vith Be moderator and once with Zr. On the aeaueptlon that J Q c - 0 , the experience! date ( i n the n i n e la

at^a

Sl)(1-J

Xl} " O.M. r r o " *«•* the value of «_ /Oj. i s 0.18. Thus J ; < r la found to be 0.22, which means that 22Z of the molecules foxwed v i a the hot reaction decompose doe to col l i s ions with the Zr atoms.

1. BAE2, M. and A3Z££., S . , J . Chen. Fhys. (In press) 2 . ESTHDP, F.J. and MOLTGASG, R., J . Am. Chen. Soc. 82, 2665 (1960) 3 . WHBASE, B. , J . Che*. Phys. 39, 2903 (1963) 4 . 3AE3, H. and /WEL. S . , J . Chea. Fhya.. 46, 1044 (1967) 5 . BAE2, a . , Che*. Hiys. Letters 3, 629 (1969) 6. &3ZL, S. and PA1S5, f., IA-1096 (1966) 7. ZAISS, ¥ . and AHIEI., S . , 4th Infomal Intern. Hot Atom Chea. Syrap.

Kyoto, Japan (1567) 3 . BACK, E.P. and GOBDUS, A.A., J. Phys. Chen. 65, 944 (1961)

MOOERATION PROCESSES OF HOT ATOMS IN THE GASEOUS PHASE' 1 ' : M. Baer andS. Atnjel.

Recently we ahowed*" that the Eatrup Wolfgang l 3 » * ' equatlo can be derived by ab In i t i o calculatlooa from the integral equation governing the yields of reactions of highly energetic atoms Moving in gaseous media. In thia derivation i t ves assumed that the average energy loss of a hot atom due to co l l i s ions with the molecules in the gas i s soa l l compared with i t s energy. If this i s the case, then a, the average logarithmic energy l o s s , which appears in these equations, cma be replaced by a the "average energy loss".

From the definition we get E

a o< E > " f g(E,E')(l-EVE)dE' (1) o

where K la the energy of the hot atom upfore the co l l i s ion and E (

i t s energy afterwards, end g(E,E')dE' i s the probability that s part ic le of energy £ w i l l be scattered in a s ingle co l l i s ion into Uit energy interval (E',E'+dET).

If 0 la the oeot ter ina angle t a ti»e esntce ot c-i-iis oyacc^i icJ.

of the hot a to* and sca t t c rc r respect ively, thea oaatslcs thir col l ls lc t : to be purely e l a s t i c one i lndai

1 - E V E - (1-3) o i n 2 | C2)

g(E,S ')d£ ' - S g g p - (3)

where b I s the inpact parameter and S(£) i s the to ta l cress section tor collision.

Substi tuting eqs.(2) and (3) in (1) we der ive:

• 0 W - O - S > l ^ s i a 2 ! W

Assuming the sca t te r ing po ten t ia l to be of the forn V(r) • Ax

2-s

ao-^- 04 E^) S<S-1)

(5)

where n i s a numerical constant, .-roa different sca t ter ing ^.jcperiments i t was sham that for actual cases s t s sose number between 5 and 10 » which uaans that a ts almost independent of energy and that the r a t io of O/o a ' s i s given i n the com:

Oj/a 2 - (1-8^/(1-63) (6)

where the indices 1 and 2 refer to two different scatte^er 1" • This re la t ion was proved numerically to hold al^o in coses vhere the scat ter ing po ten t i a l I s of the for t r } Vfr) - - L / r S l + A-Zr^2 .

Assuming Eq. (6) to be valid,one can compare the t sper toec ta l values of the different o , / a 2 r a t i o s with th* respect ive r a t i o s of ( l - S O / d - B * ) " This comparison Is given In the tab le , and the f i t , within the experimental e r r o r s , i s sa t i s f ac to ry ,

The preferabilifcy of Eq. (6) over other formulae Is discussed

foe two different •onoattmte •od*tratari

Syste* U-») a j / a 2

Reference Syste* U-») Erp. Sieor.

Reference

%-'», 0.345 0.41 + 0.03 0.382 7

3 »a - » * 0.304 0.41 + 0.03 0.382 7

%-*W 0.452 0.42 0.461 8

^ - * B e 0.980 0.42 0.461 8

* - « l r 0.260 0.26 0.265 8

^ - * H e 0.980 0.26 0.265 8

1 8 * - * a e 0.595 0.59 + 0.11 0s595 9

" F - 2 0 : , . 0.997 0.59 + 0.11 0s595 9

M

r - « t e 0.87* 0.S4 + 0.25 0.874 9

" F - 2 0 . . 0.997 0.S4 + 0.25 0.874 9

1 . 1SAHL, H. end * n a , S., J . Chen. Pl.y». (In press) 2. BAER, H., J. a w . Phys. 50, 3116 (1969) 3 . ESTOP, P.J. end 110LFCAHG, K., J . An. Che*. Soc. 82, 2665 (1960) 4 . l»IJBs!e, » . , J. Ch««. Phye. 39, 2983 (1963) 5. ESUW, P.J. , J , Cbea. Phys. 41, 164 (1964) 6.> BAEK, «. end AMIEX, S . , J. Oien. Phys. 46, 1044 (1967) 7. WAI, O.K. end UMUMD, P.S . , J. A.. Oils. Soc. 90, 3636 (1966) 8. SEEWAID, D. ami W0LFGAHB, R., J . Chen. Phy». 47, 143 (1967) 9 . anLUCBBU, II., TODD, J.F.J, and HOLFGAHG, R., Chen. Kff. Nue.

Iran. Vol.1, IAEA Vienna, 149 (1965) -10. BAEB, X. Chea. Phys. Letters 3 , 629 (1969)

THE INFLUENCE OF ENERGY ON HOT REACTIONS: Z.B. AlfawJ and S. Ami*). I» order to study the Influence of the energy of the bat atoa

on the chemical yield of a hot reaction, we subjected a bromine target to m e n a Irradiation and aeaeurad the reactions of 8 0 B r after 15-13 a le and of l r after nor* than 40 »ln. In the f i r s t case 93% of the sr praeent In that originating iron neutron capture' 1 ' and has an energy of 100-200 eV, and in the ascond case SIX of the M » r i s that foraad by lso»eri<;-J:ransitioc Iron 8 2 " » r < 2 ' and has an energy of

30-50 cV. Using Br, «s a scavenger, Che yields of the fo l lev inj reactions n i l oeaaured for each of the isotopes (denoted ^ r ) :

*Br + CB Br * CH^Br + Br

*Br + CttjBr -* CB^Br^r + B

The y i e lds , expressed as percent of the hoc atoms, were: YCT„Br " A - 1 - °' 3 £ o r S ° B r a n d 1 > 6 - °*1 f o r ^ ^ TCE2Sr _ 1 * 7 ± ° ' 1 5

for Br and 1.12 + C.2 for Br. From these results we coucluia chat l a th is range of energies the yield inireaaes as the energy Increase?. and the ratio of y ie lds of CH-Br./CR-Br decreases.

References: 1. HUGHES, D.T. and SCWARTZ, R .B . , U.S. A.E.C. Report BSL 325 a 9 5 8 ) 2. EMERY, J . F . , J . Inorg. Sucl. Chen. 27, 903 G.965)

ON THE PROBLEMATICS OF THE BILLIARD BALL MODEL FOR HIGH-ENERGY DISPLACEMENT REACTIONS IN THE GASEOUS PHASE*1); Z-B. Atfassi and S. Amid.

The b i l l iard bal l model proposed for high-energy displacement reactions In the gaseous phase has been expressed quantitatively and compared with experiment for the case of the isotope ef fect in the reaction CH,(D.) + T •* CH_(P-)T + H(D) • A large discrepancy vas found, the measured Isotope effect being 1 and the calculated 3.06, and thus i t was concluded that the model vas not-correct. We suggest that t h i s reaction I s unsuitable for testing the model,ainee, according .to the calculations in Ref. 3, most of the yield of the reaction comes from co l l i s ions in which the hot atom energy i s between 1 - 3 times the bond energy. In this energy range the assumptions of the b i l l iard ball model are not va l id .

k mora auitable reaction, occurring at higher energies, can be choaan on the basis of the following considerations* According to the b i l l iard ba l l model the threshold energy of the reaction UE + Y + RY + X w i l l be higher, the lower the internal energy gained by the R-X system compared with the tota l energy transferred to X In the c o l l i s i o n . This i * the case when the mass of X la much higher than the masa of x. I t la therefore auggeated that the model be teat«d by measuring the reactivity i n t e g r a l W of the following three reactions: CI* + CH-jX + Q^Gl + X where X - CI, Br, I awl the asterisk denotes a high energy atom. According to the b i l l iard ba l l

•Dirt the yields saoeU be i» the o r i « GK3CI > CH3BT > CEjl. while the altersmtive activated complex modal1 ' predicts the reverse order o£ yields, bauuifi the order of the bond energies la RQJ C 1 > E ^ B f >

v- 3

leftf—C*S: 1. ALFASSI, 2.K. and AH1EL, S . , I n u l J . of Cham. J* 347 (1369) 2 . LIBIT, U .F . , J . Am. Cbtsu Soc. 69, 2523 (1M7) 3 . OOSS, JLJ. sad HOLFGJNG, K., J . Cbem. Phys. 3 3 , 2002 (1961) A. ESIBZF, P .J . andWOtFCAHG, R. , J . Am. Chem. Soc. 82, 2661 (1960)

THE EFFICACY OF VARIOUS SCAVENGERS IN THE STUDY OF HOT CHLORINE REACTIONS : Z.B. AJfatsi and a Amiel.

Various scavengers used In the study of hot halogen reactions were tested for the system CI + CH-CL •+ CH, CI + CI, where the hot chlorine originated fro* neutron capture.

I t was found that a mixture of a radical scavenger and a thermal halogen scavenger Is required to obtain the hot atom reaction by I tse l f . When Br, or I - are used for scavenging, In concentrations higher than a few percent, they fu l f i l both functions. The chemical yield of the hot reaction w established to be 3.6*0.35 percent.

DELAYED NEUTRONS IN FISSION: S. Amfel.

Secant work on delayed neutron emission from fission products was surveyed, sod the experimental, phtnomenologlcel and theoretical aspects discussed In the l ight of the systematica of fission and nuclear structure (1), Evaluation of the data led to the proposal of a new systematic* for the neutron branching ratios.

Reference: 1. AMirL, S., In Physics and Chemistry of f i s s ion , Vienna, IAEA, 1969,

p. 569

A SEMJ-EMPIRICAL TREATMENT OF NEUTRON EMISSION PROBABILITIES FROM DELAYED NEUTRON PRECURSORS*')* S. Amlsl and H. Fsldttsin.

A simple correlation basad on semi-empirical considerations was derived between the neutron emission probabilities of delayed neutron precursor* and the corresponding values of (Qg - B ) , where Q. i s the total beta decay energy and Bn la the neutron binding energy. The relation found was P_ - C(4E>* where P Is the neutron emission

n ' n probability and oE - q p - B^, The consranto C and a in th* equation were evaluated from the experimental data for 19 nuclide-*, and found to be log C - 0.048*0.097 and a - 1,653±0.241. A good

fie was obtained between calculated and experimental probabil i t ies Further support for t h i s treatment i s given by Karoaukhov' a analysis

(21 of delayed proton data and the behaviour of the beta strength function.

1. AMIEL, S. and FELDSTEIN,H. Phys. Letter (in press) 2. KAHHAUKI10V , V.A., Reprint Joint I n s t i t u t e for Nuclear Research

EG-4414 Dubna (1969)

DETERMINATION OF INDEPENDENT FISSION YIELDS OF SHORT-LIVED HALOGENS IN THERMAL FISSION OF " 5 U : C. Braun and S. Amisf.

The independent f ission yields of bromine and iodine isotopes in 235

Che thermal f i s s i on of li were calculated froa the delayed neutron yie ld ra t ios previously reported . The calculations were repeated with two se t s of data for the delayed neutron emission probabi l i t i es P . One was the s e t of calculated F ' s reported i n Kef. 2, and n n f » the other the average experimental P ' s conpiled in. Ref .3 . S l s i l a r calculations were made using the experimental delayed neutron y ie ld

(4) ra t ios reported by Si lber t and Tomlinson for the braaine i so topes .

TABLE 1

Comparison of Interpolated and experimental Independent f i ss ion yields

Isotope

235 Independent f ission yie ld - U thermal f i ss ion

Isotope Interpolated l .F .Y 's

from d.n. yie ld [ a t l a s of Kef.1

from d.n. y i e ld r a t i o s of Sef.4 Isotope Interpolated

l .F .Y 's

"^to Gale, n *?;*» a

B r " B r 8 8

> r 8 9

B r 9 0

.137 ! 1 M

j l39

1.19+0.04 2.1410.12 2.1310.07 1.2910,05 3.4810.15 2.5i l0 .08 1.0810.10

1.1910.04* 2.0610.67 2.0110.71 1.10*0.28 3.4810.15* 3.2711.11 1.0310.28

1.1910.04* 1.7110.85 1.3210.72 0.8910.53. 3.4810.15* 0.9310.40 0.3710.22

1.19*0.04* 2.3210.72 1.60*0.57

1.19*0,04* 1.9210.96 1.0S10.58

* Calculated value given by Wahl*5) Th« results are coapared in Table 1, which also gives the interpolated halogen independent fission yielde compiled hy Waal*4*. All yields are ainaliscd to Uabl'a Be end I value*. It 1* seen that there la a good fie between WahVs interpolated yields end the yields calculated fron the experimental P ' s , for both sets of delayed

.. neutron yield ratios (Rafs.l and 4), The sorttwhat lower values

- 9 4 -

ftfitJltd tainc tht calculated P '« am dut to the low P 's of Br mod " ' i (toriv*3 In k*f. 2.

References: T. BIAON, C. ao.t AMIEL, S., IA-1190, 104 (1S68) 2. AHIEL, S. f:;d FEDSTEIH, H., Phys. Lett, (to be published) 3 . AHIEL, S. xn "Physics and Chemistry of Fission" IAEA SM-122/205,

p.569, Vienna 1969 4 . SILIETT, H.D. and T0HLIHSOH, R .H. , Radlochia . Act* 5_r 223 (1965) 5. KAHLp A.C., Computer Compilation of Interpolated Fission Yields.

Private communication to S. Amiel, 1969

SEPARATION OF FISSION PRODUCED IODINE BY SURFACE IONIZATION: A. Vemmria sad S. Amid.

A technique has been developed for the rapid separation of Br and I fron other fission products by selective negative surface ionization. This technique i s a modification of the one used by Aiarel et a l . * for separating Cs and Eb by positive surface ionization. The method rests on the very high electron affinity of the halogens compared with elements of adjacent atonic weight (e .g . A - 3.36 eV for Br , as opposed to 1.7 eV for the neighbouring Se , and 3.00 eV for I as opposed to 2.2 eV'for the neighbouring Te). Following ionization the halogen isotopes can he separated from each other and from other negative ions using the SOLXS isotope separator.

In choosing a good ionizer of negative ions the problem of keeping down the nuaber of electrons emitted had to be overcome; for while'a material having as small a work function as possible was sought, these are the very materials which, according to the well known Jtichardaon-Duthmen equation, are the best electron emitters. Therefore a compromise had to be found between: a) obtaining a maximum number of l o w , b) Iweping the space charge below the value that would cauae an explosion of the ion beam, c) not exceeding the maximum current that could be drawn from a l l the power supplies. It was found that a atrip of graphite f u l f i l l s a l l these requirements. Preliminary checks indicated that SOLIS could withstand overall negative currents of 400 uA without loss of s tabi l i ty . In actual work the total current i s less than 200 yA.

The ion source was built as shown in Fig. 1. Two strips of graphite are connected to isolated electrodes so that each can be heated separately to ^ 15D0°C while the other remains at l e ss than 500*C. In this way negative ions can be produced out of one of the graphite fo l ia , while the other emits no ions at a l l . One of the fo i l s Is sprayed with iodine salts and i s used for calibration, and the other contains the f ission products. The latter are deposited by

thermal neutron flux of 'V 5 * 10 n/cm sec; about half the fission products recoi l into the graphite. At the s t a r t of an experinanc, the calibration f o i l i s heated to about 1500*C, a l l the SOLlS parameters

127 are tuned to receive maximum ion current of die natural I , and then tills filament Is shut down and the radioactive one put Into operation, 'fiie act ive Iodine within the graphite i s l iberated, becomes negatively Ionized on the outer surface of the graphite, and I s accelerated direct ly towards the collector of the separator. The ions are collected on an aluminium fo i l which i s spread over a range of 13 masses. In tills way several nuclides are collected simultaneously but can be examined separately for ganmia spectrum and beta decay schemes.

With the above off- l ine technique three nuclides, I , I , I , vere clearly detected. Work i s now under way to extend t h i s technique to on-line experiments for detecting other short-lived, halogen nuclides.

High current electrodes Mjtybdenum cteenps

HeatsKefcfc I Redwactive graphite

Bis- 1 Layout of the ion source

1 . AIlAKiiL, I . , BERMAS, R.» CfiftUMCKiT, J . , F0UCli£H, R., JASTKZSBSKX, J . , JodHSOl, A... KLAPISCil, H. *nd IiilLUC, J . , Arkiv fur 'rhyslk 36, 77 (1966)

ON-LINE EXPERIMENTS ON SHORT-LIVED RARE GAS FISSION PRODUCTS: S.Amist Y. Nir-EL M, Oroo and E. YtMin.

Studies on. raze gas f i ss ion products famed i n the thermal f i ss ion oE U are being carried out using the SOUS on-line isotope separator. There are three vain alas in these experiments:

a) To aeasure the half- l ives of the f iss ion produced heavy isotopes of Kr and Xe , sad their decay products. The ions are accumulated on the collector and their decay followed after switching off the

94 neutron beaai and closing the ion shutter. Hie half- l ives of Kr and 2 * 3 Xe were found to be 0.194 + 0.005 sec and 0.302 + 0.045 sec respectively.

• b) To obtain data concerning delayed neutron characteristics in the f ission product region of Kr and Xe . Here certain d i f f icul t ies were encountered due to the high background of neutrons leaking from the bunker around the target. Only one precursor was observed, namely 93

*x , with a h a l f - l i f e of 1.27 + 0.12 sec , i n good agreement with the accepted value. Work i s being done to reduce the neutron background.

c) To study the influence of the operating conditions on the transfer dates between the fission event and the arrival of the products at the collector. iGnowledge of the transfer time i s necessary for calculating the Independent yields of short-lived krypton end xenon fission products (aee next a r t i c l s ) . The start of the transfer i s obtained by observing the irradiating neutron beam profile when the beam i s switched on, and the end i s found from the corresponding act ivity profile of the f iss ion products at the collector, as measured with a plast ic sc in t i l la tor . The values obtained range fro* 0.25 to 1.7 sees , according to the conditions prevailing during the run.

PRIMARY MASS DISTRIBUTION OF Kr ISOTOPES FORMED IN THE THERMAL FtSJwU OF 3 M U : B. Ehrtttbfff, H. Fsfcwtein, M. Oron and S. Amis).

The SOhlS isotope separator worn used to Measure the primary yields of ir isotopst; produced in the therasl f ission of uronlufl. Wo type* of targets were used m an emsusrion source of the gaseous fission products. One contained 2 g of 932 enriched 2 3 5 U in the form of V Og* mixed with * 8 g barium stearate; ch* other contained the equivalent weight of uranlua in the form of ursnyl stearate. The

q 2 target was exposed to a flux of * 2x10 n/cst sec in a neutron beast V*** The gaseous flaaion products diffusing through the powder vara strcpt Into the ion source of the Mass separator by a street of He containing 21 or l ess Ur carrier gss. The separated isotopes

- 97 -

were collected an an aluminium f o i l , and counted la a set of beta counters. Since the total transfer time from fission until the collection of the fragment on the fo i l varies considerably froQ one experiment to another, an on-line measurement of this tine interval was made after erch experiment (see preceding a r t i c l e ) .

The results obtained so far for the primary f iss ion yields of ICr isotopes (extrapolated to zero irradiation time] are given in the table.

TAULE 1 Primary fission yields of Kr isotopes

Isotope 91 Yield relative to ;<r

8 5Kr» 8 6Kr 87.. s C 89,. Kr 9 0

K r 91. .\r 9 2 i ;r »Kr »*Xr 9 \ r

0.005 + 0.0005 not detected 0.16 + 0.015 0.57 + 0.05 1.45 + 0.3 2.55 + 0.3 1.00 0.24 + J.03 o:06 + o.oi

detected, Inconsistent results detected, inconsistent results

The delayed neutron emission in masses 53, 94, 95 wi l l now be determined. For this purpose the exact cross contamination and amount of KrU formed are being measured, as these have the same effect on the results as neutron emission. Similar ueasureaents w i l l be aade for Xe.

RAPID SEPARATION OF ANTIMONY ISOTOPES FROM * * U FISSION PRODUCTS: H. F«lditain«ndS. AroW.

Attaapts to find a satisfactory method for the rapid separation of fission produced antiaony v*x% /.oatinuad. In the procedure described p r e v i o u s l y ^ , the scrubbing solution containing the f iss ion products and 1 mg/al So as carrlsr was passed through a reducing uediua which separated the antlaouy froei t in and te l lur i te by converting i t to SbH,, The SbH, was concentrated prior to i t s adaission to the SOLIS isotope separator by converting i t to aacal i ic Sh and then to volat i le SbCl*. However! this aatnod was abandorad because I t was fcaposaibls to obtain sufficiently rapid transfer frae Che caeaical unit

- 9 8 -

through th* relatively long connecting l ine and. needle valve to the SOLIS. Hor could the SbH- be concentrated by increasing the antimony carrier In the scrubbing solution (to 10 mg/ml), since then the atibine decomposed In the Ion source end, due to i t s alow evaporation, gave a steady beam of antimony independent of th* feed.

A high intensity beam of antimony was obtained using so l id antinony or i t s oxide placed in an external oven, near the ion source. This permits off - l ine work with chemically separated antimony, but i s only suitable for isotopes having half-Uvea of several minutes, since i t takes ** 5 min to mount the oven and obtain a steady ion bean,

Ihe long memory of the ion source for antimony i s another serious problem. I t seems that a satisfactory system must await perfection of an elevated temperature ion source capable of operating on-line with a chemical separation system.

Eeference: 1. VHLDST2IN, II. and AHIKL, S . , 1A-1190, p. 100 (1968)

SOLIS ISOTOPE SEPARATOR: AUXILIARY INSTRUMENTATION AND OPERATING CONDITIONS,

a) Blah Temperature Ion Source and Ovena. Work with many f iss ion products (e .g . Sb and As) ca l l s for on

elevated-temperature ion source in order to achieve better efficiency and shorter residence times ss wall as to a l leviate "memory" effects observed with these elements in the ion source. Redesign of the Nielsen- type ion source resulted in a minimum of 1600*C at the coldest point of the discharge chamber and about 2000*C around the gas i n l e t . Ovens for of f - l ine work with so l id feed adapted to the ion source were designed and worked successfully up to 1650*C. Attempts to attain higher temperatures are in progress . (11, Oron and Z. Segal).

b) Controlled Speed and Delay Tape Transport System with Four Counting Positions.

A tape transport system (Fig. l ) which permits the removal of davgbtars of the decaying isotopes at a desired controlled ipeed was b u i l t . The system has four counting positions, two at the point of impingement of the beam and two others at a desired time delay. The taps i s conducting, for loo charge removal, and the whole system i s under vacuum of 10 torr. (Ch. Gavish and S. Amial).

W/'r'

F i s . 1 Tape transport systea

1 Vocuum in collector

1 + 7 X ICf 6 torr

•

• 2 x 10" 6 twr

V » *

- 41 V * +

* 8 5 6 6 8 7

Mass r U.nber

Fig. 2 Typical activity distribution of Kr from 'J f iss ion, obtained at the and of the Collector. Running conditions were 40 UV acceleration voltage, ,and 10 yA total krypton current. Ihe pressure at the collector was 7><10"5 torr. Hie diameter at half maximum of the C 5Kr peak ia 1.54 DM and enrichment factor about 10*. The act ivity peak at aaas 86

ia due to 8 3 Krli + ions foned.

c) Multi-purpose Collector End-Plate.

A. collecting system which permits both the fast Introduction of end-strips without breaking thft vacuum, and adjustment of the point of impingement of the beam to a selected position,was designed and bui l t . The system uses trol ley mounted Faraday cups and beam scanners. CM. Oron, J. Folkman and H. Levi)

d) Beam Shape and Cross Contamination Measurements. The Influence of the vacuum i n the system and the ion source

parameters on the beam shape and cross contamination of beams of neighbouring a a s s e s ^ i s being measured. Partial results have already

{2)1 been published v , and Improvements of the machine have been made to obtain lower crocs contamination, A typical activity distribution and the Influence of vacuus on i t s shape are shown In Fig. 2. (M. Oron).

References:

I' S ^ i J"» V a C U U * ' ^ C l 2 ) ' 5 " - S 5 2 <1969) 2. OBOS, « . , Vacuum, 1£, {12), 567-570 (1969)

THE SZILARD-CHALMEHS REACTION ON GALLIUM PHTHALOCVANINE IN A HIGH NEUTRON FLUX'": R. Rafwloff and E. Yellin.

Enrichment by the Szllard-ChaJmers reaction* la usually carried out to obtain high specific act iv i t ies of radionuclides produced by neutron irradiation. However, the high radiation fluxes required to produce Intense sources cause radiation damage to the target material In moat cases, thereby bringing about a sharp decrease In the enrichment factor. The phthalocyanlnes* »5* are particularly suited for the SzlXard-Chalmers reaction because of their high chemical and radiation s tabi l i ty and because there Is no exchange between the free metal lone in the ex­tracting metal and the complexes. This study was aimed at investigating the e£f«cta of neutron flux** of up to 2 x 10 neutrons cm" sec" on the yield.and enrichment of Ga produced from gallium phthalocyanlne targets.

The activity of Che 7 2 c » in both the solid and liquid phases vas measured using a 3x3"'HaI spectrometer in conjunction with a multichannel analyzer. The extractaots were dilute or concentrated sulfuric add at various solvent-solid rat ios . The best results were obtained by axtrac-lon with cone, sulfuric acid at room temperature and at a minimum ratio of solvent fto solute. Thus an enrichment factor of 514 was obtained for a sample Irradiated for 20 min and extracted with cone, sulfuric acid at 25*C, at a ratio of 5 t l sulfuric ssld to gallium phthalocyanine. Expert-

- 101 -

merits to decrease the radiation damage by irradiating Che sample in a lead shield, thereby reducing the y and X radiation which cause the radiation decomposition of the complex, showed that the enrichment factor can be further increased.

References: 1 . SCHWARTZ, A . , RAEAELOFF, R, and YELLIN, E . , I n t . J , Appl.

Rad. I s o t o p e s ( i n p r e s s ) 2 . SZ1LAED, L. and CHALMERS, T . A . , Mature 1 3 4 . 462 (1934) 3 . PAYNE, B .R . , SCARGI1L, P. and COOK, G . B . , R a d i o i s o t o p e s S c i . Research,

Proc. I n t . Conf. P a r i s 2 , 154 (1957) 4 . COOK, G . B . , J . Inorg . Hucl. Chem. 1 4 , 301 ( I960) 5 . MERZ, E. Nukleonlk 8. ( 5 ) , 248 ( 1 9 6 6 ) .

A COMPUTER PROGRAM FOR ACTIVATION ANALYSIS WITH VERY SHORT-LIVED NUCLIDES' 1 1: M. Wiernik.

A Fortran program was written to fac i l i ta te the handling of the large amount of data obtained when repeated measurements are made using very short-lived nuclides (half- l i fe *> 1 sec) .

The input data needed are: weight of each sample or standard, total time of each measurement, in i t i a l and final fractional dead-times, and the measured spectra. The progrun then calculates the response of the detector, makes corrections for decay during the measurement and fox dead-time losses , and calculates the amount and concentration of the element being analyzed, as well as the absolute and relative errors of each analysis.

The output comprises: a) the input dat*. for each measurement, with the spectra printed

in linear and logarithmic scales simultaneously ;

b) the calculated parameters of a l l the standards used for the calibration of the detector;

c) a detailed report of a l l the determinations performed with each •ample, as wall aa the results and error*.

Reference: .1. WIERNIK, M., IA-1204 (1969)

COMPARISON OF SEVERAL METHODS FOR THE CORRECTION OF DEAD-TIME EFFECTS IN GAMMA-RAY SPECTROMETRY MEASUREMENTS: M. W a n t * .

Several methods hay* beam proposed for the correction of ds«d-tiaw affects In the measurement of ••***-r*7 spectra of short-livsd nuclides. AM In our case we normally measure only on* fast-decaying nuclide in the presence of a blah background (reactor hall) during several ha l f - l i ves^* , the choice i s limited to three methods, based

respectively on: a) measurement of the total true and live tines during the experi-

ment* ; (4) h) codtlnuous measurement of the fractional dead-time x ;

c) measurement of the losses suffered by the pulses supplied by a precision pulser .

AS a l l the proposed methods are iu principle correct, the accuracy of the correction must depend on the accuracy of the measure-Bent of the parameters used In the different formulae.

Preliminary experiments to compare the methods show that,while with moderate dead-time a l l three methods are equally good, for very high values of the dead-time (70-90%) a l l three are in error hut methods a) and c) are somewhat more accurate than b) .

References: 1. WIERNIK, II. and AMIEI. S., IA-1190 (1969) p.112 2. SHANKS, J.,lEgS^2671-2<l 062) Section 5, p.15 3. JDHOD, E., CEA-R 2980 (1966) p.55 4. WIERNIK, H. and AKIEL, S. , J . RadloanaL. Chem., 3., 245 (1969) 5. AIDERS, O.U., Nucl. Instr. and Methods, 68 205 (1969)

X-RAY FLUORESCENCE DETERMINATION OF URANIUM SOLUTIONS WITH A LITHIUM DRIFTED SILICON DETECTOR: C. Shenberg and S. Amiel.

Determination of elements by X-ray fluorescence i s a well known

technique , the determination being baaed on the intensity of the K. or L X-rays of the sample as compared with known standards. However, these results are accurate only in the low concentration range, since «t higher concentrations self-absorption becomes important and thus i t i s Impossible to obtain a linear standard curve.

tt\ in which

backscattered X-rays are used as a normalizing factor to overcome the problem of self-absorption. For this purpose the source - target assembly described by Giauque J was used, where the detector sees the X-rays of the excited element as well as the backscattered X-rays of the target. If the backscattered X-rays are very close energetically to the excited X-rays it can be assumed that the mean paths for both, are the same. Hence the ratio of sample X-rays to backscattered X-rays will give a true measure of the element being determined, independent of self-absorption.

- 103

Uranium nitrate solutions in the range 0.5 mg/ml - 500 mg/nl were

analyzed. The solutions uere prepared from MBS standards. A sscple of

5-7 ml of each solution was transferred to a plastic container with a

mylar bottom. The exact volume of the sample is not important, since

peak ratios are used In the calculations. The samples were counted on 2

a lithium drifted silicon detector (25 mm area) coupled with a 400

channel analyzer. The resolution was about 850 eV in the vicinity of 241

22 keV. A 1 mc Am source was used to excite the K X-rays of an iodine

target, and these in turn excite the L X-rays of uranium. Although

the iodine K X-rays (K » 28.610 keV, K n = 32.292 keV) have somewhat

higher energies than the uranium L X-rays (L. • 13.6 k e V ) , iodine was

chosen as the target in preference to lower atomic number elements

since with the latter overlapping occurs; for example, Cd has its

K X-raya at 23.172 keV, which overlaps with Che L X-rays of U at

20.163 keV. Only ths L X-rays of uranium were used in the calcula­

tions since the L0 and L X-rays are influenced by the absorption P v

edges of U (L * 21,756 keV, L - 20.947 keV, L • 17.167 keV),and as

The results obtained show that, in contrast to the conventional

method, the count is proportional to the uranium concentration, in the

entire range studied (see fig. 1 ) . The urror in individual determina­

tion is between 2 and 3%.

IQfL-

Jig. 1

Analytical curves for uranluu determination, using b«cksc*Lcered X-rays (straight line) and conventional nethod (non-linear curve)

1. IHOOCS, J.K., Analyst 91 , 1088 (1966) 2. «OT» J . S . , In te r . J . Appl. Radlat. labtop. 18, 383 (1967) 3 . XLECU, J . F . , UCKL - 1766, (October 3 , 1966) 4 . 1 N U , a.It . , pr ivate cu—untcaclon 5. GLUJQOE, R.D., Anat. Cham. 40, (13) 2075 (1968)

NEUTRON ACTIVATION ANALYSIS OF URANIUM BV MULTIPLE GAKMA RAY RATIO DETERMINATION: M. Mania! md S. AmM.

(1 2) Ibe method of multi- j.e g a u u ray peak r a t i o determination ' has been applied to the nondestructive neutron act ivat ion analysis of natural uranium In different aedia.

In the ganaaa spect r in obtained from an i r rad ia ted uraniua sample measured with a Ge(Li) detector j one can eas i ly identify gawa peaks

fori peaks is a Measure of the quanti ty of uranium in the i r r ad ia ted 3 » p l e , provided that the uraniui i s of natural isg topic composition. In an unknown saaple the ra t ios between the integrated areas of the different photopeaks are calculated and compared with"those obtained for a uraniuti standard. Tue uranium concentration xa the' sample i s calculated from the photopeaks whose ra t ios correspond, trithln the er ror l i m i t s , to those of pure natural uraniua. Up to 9 independent resu l t s may be obtained frota a s ingle measurement, Xlie overa l l error i s +2'£ for a wide range of uraniua concentrations (from 10 pptn up to HOZ).

References i 1 . :'u*:aL,ti., GILA!, J . and &JIEL, S., J . tfadioan. Chen. 2, 395 (1969) 2. i£AHT£L, a,, 3in<G-*'iU*Gp P. and A-aEL, 3.,Anal.Chem. ( in p ress ) .

LITHIUM ISOTOPIC ANALYSIS BY NEUTRON ACTIVATION AND SIMULTANEOUS MEASUREMENTS OP »Umd "N: M. Warnik and S. Amiat.

The isotopic analysis of lithium i s normally carried out by mass spectrometry, Where nuclear methods nave been applied, these have re l ied on die determination of only one of the isotopes ( L i o r L i ) , combined with chemical assay of the t o t a l l i thium content. In the present work two kno.ro methods for tiie act ivation analysis of the individual isotopes were combined to obtain a simultaneous determi­nation* The methods chosen ar« nondestructive and the ha l f - l ives of the nuclides produced are short enougli to permit multiple rapid determinations, men as nay be done with a fas t snu t t l e rabbit .

When an aqueous solution of a lithium compound i s i r radia ted In a thermal neutron flux, the following r e a c t i o n take place:

v.

Lt(n,Y) U •+

ID

(2)

'the neutrons emitted by the excited s ta te of 0 (with a ha l f - l i fe of 4.14 sec) give an indication of the asount of Li present , while the hard beta rays (13 ileV max) Knitted by O.tiS sec ui can be measured with a Cerenkov counter* ' and the count r a t e , i f £c I s not too high, i s proportional to the amount of Li present.

Jeutrons and hard oeta rays were treasured simultaneously vitii the arrangement i l l u s t r a t ed in Fig. 1. Xne neutrons are detected by three JF, counters embedded i n a cadmiisa-shielded paraffin block (d)-2he Cerenkov counter (c) consists of a 3" * 2" cylinder of perspex optical ly coupled to a photomultiplier. A perspex aosorber (o) i s added, when needed, in order to reduce the nigh counting ra te of the Cerenkov counter. The ent i re assembly i s placed inside a ca&ziiEi-covered lead cas t le with 10 ca thick wal ls . A shield of 15 en thick paraffin bricks (not sitovn l a tiie figure) surrounds the- c a s t l e .

several samples of known isotopic composition were prepared by mixing appropriate amounts of the enriched isotopes. The enriched isotopes themselves were taken as standards. The samples and standards were i r radiated for 12 sec and, a . t e r a 0.6 sec delay (for exi t and recoi l } , the simultaneous accumulation of neutron counts (12 sec) and Cerenkov counts (2.4 sec) was s ta r ted . After appropriate delays, a second measurement was made in eaca case in order to subtract the remaining background.

Pig, 1 Arrangenint for siaultanaous Mwurwunt of neutrons and hard bata rays froM activation of 6Li and 7L1. A - side viaw; U - frcm above* a - pneuaatic tub*; b - parspex abaorbex; c - Carankov datactor;

d - paraffin block with i)F 3 detactora •

Jita the present arrangement, Che calibration factors were 425 counts/mg-atoa of °Li and illO couuts/ug-atoK of Li (for their respective nunting period*}, /malyses of samples ranging from 1 Co 5 *to*-X of LI gave relative errors varying between 3.25 awl 3.42.

inferences: 1. HaasiUC, -i. and .:iXEL, a., J . 3adioaaal. Cliem. 3 . 393 (1969) 2. .XULL, 3 . and IS! iaHI, "/., Anal. Chcra. 3_5, 566 7l?63) 3 . UJ^UId, «.«.» J . ladioaoal . Cuem. _!, 349 (196B)

DETERMINATION OF TRACE ELEMENTS IN BIOLOGICAL MATERIALS BY NEUTRON ACTIVATION AND X-RAY SPECTROMETRY: M. Mantot and S. Amial.

Biological Materials consist essentially of l ight elements {C, 0, H, :i) and common electrolytes (Ha, K, CI, Ca, :tg). Many of the heavier trace elenents to be determined in such saoples give, upon neutron activation, radioactive isotopes -jtiose. characteristic ganma ra/S are masked by the activation products of the electrolytes . As a result the determination of these elements Ly nondestructive ganna spectrometry becomes inaccurate or even impassible. On the other hand moat of these heavy isotopes emit, dueing decay by electron capture or internal conversion. X-rays Which are characteristic of the species In question. These X-rays are not subject to interference either by the gamma rays of the activation products, which have higher energies, or by the X-rays of the matrix elements, which have lower energies due to lower atomic number.

The X-rays are readily resolved by high resolution (^ 350 eV> Si(Li) detectors, permitting the simultaneous determination of a great number of elements. In biological samples such-nondestructive X-ray

. spectrometry raises the possibi l i ty of eliminating many time consuming chemical separations, and increasing the accuracy and precision of the results . A program to study the sensit ivity of the method for various elements has been Initiated. So far iodine, cesium, copper, zinc, selenium and cobalt have been studied in simulated biological samples.

NONDESTRUCTIVE ACTIVATION ANALYSIS OF GALLIUM: R. Raffmttoff and E. YsWn.

A simple method for the rapid nondestructive determination of gallium by neutron activation was developed . The favourable conditions for th is analysis are the activation cross section of 4.0 barns for Ca, and the 14.3 h hal f - l i fe and convenient mode of decay of Ca.

Standard solutions ware prepared by dissolving iptctroscopically

- 107 -

pure Ga natal in mineral acid. Standards and reagent blanks ucre Irradiated for 5 - 1 5 min at a flux of 5 r 10 neutrons ca see - .

72 The activity of the Ga produced vas measured using a 3x3 Dal crystal in conjuction with a multichannel analyzer. A standard activity-concentration curve for gallium vas drawn, from which the' galliio content of unknown samples could be read off.

The sensitivity of the method is better than 0.1 ug Ga/g sanple.

Feference: 1. R. Rafaeloff and E. tellin, Israel J. Chen. 7, 173 (1969)

NEUTRON ACTIVATION ANALYSIS BY A COMBINED CAPTURE AND DECAY GAMMA SPECTRUM METHOD 1": Y. Eden.

Conventional neutron activation analysis Is based on measurement of the energy and half-life of the decay gamma rays emitted following neutron capture. However it has been suggested thai: the capture gamma rays, or a combination of capture and decay gamaa rays, may b<* measured for analytical purposesv . In the present work the combined measurement of the capture and decay gamma spectra emitted under bombardment by the same pulsed thermal neutron beam vas studied. The advantage of this method is that it eliminates the need for time-consuming half-life measurements. The two kinds of gamma ray spectra, which fall in different energy ranges, are measured separately during alternate pulses of the neutron beam and recorded in separate sections of a multichannel analyzer.

The neutron source used was a Cockroft-Walton type 150 kV accelerator for deuterium, with a pulsing device. Neutrons of 2.7 or 14.3 MeV are produced by the (D,D) or (D,T) reaction respectively. The gamma ray spectra were measured with a 3" * 3" Nal crystal and a multichannel analyzer system synchronized with the pulsed neutron beam. The system was set to record the wide range of gamma ray energies from 0.5 to 10 MeV.

Samples of copper, aluminium and manganese ware analyzed. As an example, the capture gamma ray spectrum obtained by irradiating a copper metal disc of 10 cm radius and weighing 2 kg is shown in Fig.la . The corresponding decay gamma ray spectrum, Fig.lb, shows the characteris­tic energy peaks of the Cu and Cu radioactive Isotopes.

The results obtained for macro amount samples of individual elements give a basis for further development towards a quantitative method. For mixed samples, it would be necessary to use high resolution detectors

- 108-

mi rnaniitar —Mini* to ruolv* the complex I M i apactra. The tecaalqae akmld then be applicable to eaaplee auch «» are encountered la priaary geological aurvey, Induetrial control, oceanographle raaaarch aad developaeat atudlea.

2 0 T T T T

o

I I | I I I I | I I I

I i • i i l l i i i 1 • . i • I

0 50 100

S<n*lt:Cii-iraM '

H»:2000o7- „ , NMron lt«:L07 « lOJqbn'MC-Lwe count :4ltin

100 Channel Number

H i - l ladiatlve capture geese apectrim (a), and decay gaeaa apectrum (b). Weight 2kg; Irradiation and live time count 4 Bin; background aubtraeted; ncutru f'.ux 1.07 x 105 n/ca? aec froa a (D,D) reaction;

detector 3" * 3" NaZ crvetal

Kefarencee; 1. IM", T., J. ladioanalytical Chan, (in preaa)

OLDWtLL, X.C., MILLS, W.K., Jr., ALLEK, L.S., BELL, P.R. and a.L., Science 152, 3721 (1966J

- 109 -

RADIATION CHEMISTRY.

The work of the radiation chendstry group «*s directed along the following l ines : a) Hie study of charge transfer reactions in gaoata irradiated solutions, both organic and aqueous, and of the effect of posit ive ions on hydrogen y ie ld , b) The study of the mechanisa and kinetics of gaana radiation induced chain "flehalogenation reactions, c) Pulse radiolysis of aqueous solutions of lanthanides. d) The study of photolydc isotopic exchange between Iodine and iodoaroaatic compounds. e) The study of inorganic redox reactions by tadiolytic methods. The results obtained in these studies are summarized in this section.

GAMMA RADIATION'INDUCED CHAIN DECOMPOSITION OF TETRA AND PENTACHLOROETHANE IN CVCLOHEXAN6 SOLUTIONS. M. Katz. A. Horowitz and L.A. Rajbenbach.

Radiation induced reactions in solutions of C„C1,H, and C-C1.H 2 4 2 2 5

in cyclohexane were studied over the temperature range 150-230 and 50-200'C respect ively. I t was found that the solutes undergo a chain decomposition s imi lar to that of hexachloroethylene reported previously 1 . The kinet ic analysis of the chain reaction permitted determination of the Arrhenius parameters for chlorine elimination from the CjCl„H2 and C„Cl.a radicals re la t ive to the corresponding parameters for hydrogen abstraction from cyclohexane by these radicals (reactions 4 and 5 below). The re la t ive parameters for hydrogen and chlorine abstraction from C.C1.H- and C-C1.H by cyclohexyl radicals were also determined {reactions 2 and 3) . The resu l t s are suaoarized in Table 1 i n terms of the following react ions:

2 c-C s U 1 2 A«*-> 2 c - C 6 H u + H 2 (1)

1 > C-C H CI + C.C1 ,H, c-C.H„ + C-Cl H. 1 6 11 2 a-1 6-1

6 U 2 ° 6 " 7 —* <-V'l2*W5-„

(2)

(3)

-v * C 5 C 1 A + c l

2 rii-. > 6 ^ +C-C.H., J 2 n-1 7-n 6 11 (5)

IASLE 1 Relative Arrhenius parameters

Solute log(A 2/A 3) Ej - E 3

kcai log(A 4/A 5) E 4 - E 5

kcai

W 2 C2C15H

1.50S -0.8S 1.065 -3.78

5.63 8.1 5.91 6.86

The resul ts seem to indicate that the act ivat ion energy of the uniraolecular chlorine elimination reaction in chloroalkyl radicals (reaction 4) i s lower in cyclohexane than in the gas phase.

Reference: 1. HOROWITZ, A. and RAJBENBACH, L.A., J. Phys. Cham, (in press)

DETERMINATION OF ARRHENIUS PARAMETERS IN THE GAMMA INDUCED FREE RADICAL CONDENSATION REACTION BETWEEN ALKANES AND CHLOROETHYLENES; A* Horowitz and L.A. Rajbenbsch.

In previous work* ' ' ' the kinetics of free radical chain condensation reactions between alkanes and chlorooleflna was studlsd and the mechanism of tbasa rsactloos deduced. In the present work competitive kinet ic Methods were applied to obtain the Arrhenius parameters for the propagation steps of the chain condensation process In three of the systems studied before, namely C.C1.H - cyclohexane, d a C.ClgB. - cyclohexane, and trans C^Cl H, - cyclohexane. The competitive kinet ic method used in the present study obviates the need for the two assumptions made i n the previous work, namely *) that the radiolyt ic y ie ld of solvent radical Is unaffected by the presence of solute,and b) that Che sum of the steady s ta te concentra­tions of a l l the radicals i n the solution is constant.

Ilia kinet ic parameters were obtained by Irradiating ternary solutions containing cyclohexane, C-Cl. (as the competing so lu te ) , and one of the chloroolefins studied,and determining the relat ive y i e ld of condensation products as a function of irradiation temperature. The results are i n general close to those obtained previously in binary solutions.

References:

1 . HOROWITZ, A. and RAJSENBACH, L . A . , J . Amer. Oiem. Soc. 9 1 , 4626 (1969) 2 . lOaOHITZ, A. and RAJBENBACH, L . A . , i b i d , 9 1 , 4631 (1969) 3 . HOROWITZ, A. and RAJBENBACH, L . A . , l a i d ( i n p r e s s )

NEGATIVE ION FORMATION IN THE RAD 10LYSIS OF ARYLCHLORIDES IN CYCLOHEXANE SOLUTION: A. Horowitz and LA. Rijbsnbach.

Work on the radiolysia of benzylchlorid* (BcCl) and chlorobenzene (FhCl) in eyclohexane solutions was continued, with particular stress on the mechanism of electron attachment to FhGl in the l iquid phase.

In $*M phase studies on PhCl < 2 ' the findings were consistent with a dissociative electron capture mechanism proceeding via a molecular solute

<fhCl>":

(1) (2)

Since reaction 2 involves a change In the electron orbital symmetry it will occur only when energetic electrons impinge upon the substrate or when thermal electrons collide, with vibrationally excited Phcl molecules.

- 1 1 3 -

ID Che present radiolyt ic work i t Is assumed that attachment of a thernal e lec t ros occurs, resul t ing In the formation of a (PhCl)~ anion which then s p l i t s off a chlorine atom:

(FoCir > Ph" + CI (3)

The CI reacts with the allcane solvent to form HC1. The occurrence o£ reaction 3 does not involve a change i n the electron o rb i ta l symmetry of (PhCl) . In accordance with a mechanism suggested for HF formation

(31 in the radiolysis of perfluorocarbons in allcanes ' , solvent par t ic ipat ion in the t ransi t ion s t a t e of reaction 3 xt* proposed.

References: 1. HOROWITZ, A. and RAJBENBACH, L.A., in IA-1190 (1969) p.126 2. CLARKE, D.P. and GOULSON, C.A., J . Cheat. Sec. (A) 169 (1969) 3. RAJBENBACH, L.A.- J . Fhys. Chem. 2 3 , 356 (1969)

KINETICS AND MECHANISM OF RADIATION INDUCED SYNTHESIS OF SUBSTITUTED CHLOROOLEFINS^: M. Kate, A. Horowitz and LJ>. Rajbtnbach.

Ihis work i s concerned with the application of i r r ad ia t ion for the purpose of synthesis . The gamma radiat ion induced free radical chain condensation reaction between hydrocarbons and chloroolefias was considered a promising route for the synthesis of a var ie ty of potent ia l ly useful compounds.

The optimal experimental parameters for maximum product y ie ld were derived from the k ine t ic analysis of the following free radical chain reaction sequence* where EH represents hydrocarbons and C 2 C 1 m H 4-tt c f l i o r o e t l i y l e n e s :

CD

(2)

<3>

(4) R + R * 1 (S)

* + "V»A« —> r S S S : w 2 R C 2 C V W > J <7)

Xt was concluded that in a teoparatuca range where k, > k 3 t i i m

limiting condensation product yield is given by the following expression:

- 114 -

where a is a constant converting G values Into units of rates of formation, and G(!t ) represents the radlolytie yield o£ R radlcela In pure JH . The overall activation energy of the condensation process turned out to be close to that of reaction 3. The optimum temperature for the condensation process was found to be about 250"C. The G values

4 of product formation were well in excess of 10 under the experimental conditions used.

aeferences; 1. HOIOwTTZ, A. and BAJBENBACE, L.A. * Proc. Symp. on Large Radiation

Sources for Industrial Processes* IAEA, Vienna, 1969, p.21-29

ISOTOPIC EXCHANGE INDUCED BY EXCITATION OF THE IODINE-IODOBENZENE CHARGE TRANSFER COMPLEX: A. Levy, O. Mayerrtein and M. Ottotonghi*

The mechanism of the pbotochenically Induced laotopic exchange between molecular Iodine and lodobenzane has been studied. Previous suggestions that the isotoplc exchange la induced by excitation of the iodine molecules were shown to be Incorrect, as very slow exchange was observed when solutions of iodine and iodobenreue In cyclohexane were irradiated selectively In the Iodine band.

Excitation In the O.V. range resulted in significant exchange, but the Interpretation of the data was inconclusive, due to the overlap between the lodobenzenc absorption and that of the Phl.I. charge-transfer complex. The study of the effect of varying the concentrations of losobemseue and iodine also allowed no conclusive discrimination between the two possible absorbing species.

The problem was solved by determining the dependence of the exchange yields on wavelength of irradiation at 365, 334 and 313 nm. Calculations assuming lodobensene to be the absorbing species resulted in a significant decrease In the yield with the change in the wave­length froa 365 to 334 end 313 nm. However, when the absorbing species waa aasuawd to be the iodlna-lodobenzene complex a constant yield Independent of wavelength was obtained. It thus seems that the latter assumption is correct. Further work on the detailed mecha­nism is in progress.

* Htbmw Unhnnity. Jwuntwrw

EFFECT OF LIGANDS ON REACTIVITY OF METAL CATIONS TOWARDS THE HYDRATED ELECTRON.' PART 2. EFFECT OF GLYCINE, ETHYLENEDfAMlNE AND NITR1L0TRIACETIC ACID^- D. Meyerstein and W.A. Mulac*

The speci f ic ra tes of reaction of the hydrated electron with complexes of glycine, ethylenedtantLne and n i t r i l o t r i a c e t i c a d d with different cations have been determined. The effect of the degree of complexatlon has been studied in d e t a i l . The removal of the l a s t water molecule from the inner sphere s ignif icant ly decreases the speci f ic ra te of reac t ion . An analysis of the r esu l t s proves that the observed speci f ic r a t e constants are in disagreement with those predicted by the Marcus theory for hydrated electron react ions . Alternative mechanisms for the reaction of the hydrated e lect ron with inorganic complexes are discussed.

Refer mce: 1. MEYERSTEIN, D. and MULAC, W.A., Trans. Faraday Soc. 65,. 1818 (1969)

REDUCTION OF COBALT (III) COMPLEXES BY MONOVALENT ZINC, CADMIUM AND NICKEL IONS (N AQUEOUS SOLUTIONS^: D. Meyeistein and W A Mulac*

The spec i f ic ra tes of reaction of Zn , Cd , Ni , and e with a se r i e s of Co(III) cotplexes have been determined. The mechanisms of reduction and t h e i r dependence on the e lec t ronic s t ruc ture of the mono­valent cations a re discussed.

Reference: 1 . MEYE8STEIN, D. and WDLAC, W.A., J . Phys. Chenu 73, 1091 {1969)

THE EFFECT OF LIGANDS ON THE CHEMICAL PROPERTIES OF MONOVALENT CADMIUM IONS: D. Meyerstein and WJH. Mulac*

Monovalent cadmium ions , Cd , formed by the react ion of hydrate* electrons with divalent cadmium ions, have been shown to b« powerful reducing agents^ . The specific r a t e s of reduction of dif ferent inorganic compounds, including a se r i e s of Co(lII ) complexes, by Cd have been measured. I t has been suggested that Cd iona reac t • • a

(21 reducing agent both via the outer and inner sphere mechanisms* '. Referenda: 1. For example, BAXENDALE, J.H. and DIXON, R.S., Z. Physik Che*.

(Frankfurt) 43, 161 (1964) 2, MEYERSTEIN, D. and MULAC, W.A., J. Phys. Choi. 73, 1091 (1969)

Argonna National Laboratory, llllnoh, U.S.A.

THE PULSE HADKM.YSH OF AQUEOUS SOLUTIONS OF LANTHANIDES: Eu«ll|. Ybtl l l l . SMflIU aei TMIIU: M. F n t f , V. Ttndhr and A. Fsddsr.

Trees fear epectra of the divalent ioa« of Eu, Yb end Sn haw M « • • • ! ! < Im aeatrel aaaaoua solutions irradiated by the pulse rsc to lye l s technique. Iha aolar absorption coef f ic ients at th« absocstloa aaxlaa were found to b«: for Eu(II) t - 1600, CjjQ - 700; for Jb(II) t 2 M - 1600, c 3 5 0 - 600; for S a ( « ) ! , „ - 300. The accuracy of these values I s within + VOX.

Eu(II) and Yb(II) were a l so foraed by trapping 'a ae ta -phosphete g lasses , a technique described by Treinln e t e l . , and t b e t t abeorptlon spectra, were Measured. Absorption arnrtna were found a t 260 r 5 and 325 ± 5 nn for EuCII) and 360 + 10 na for Yb(H) , i n good agreeaene with the values found in aqueous so lut ions .

The spec i f i c rate constants of the reactions of Eu(II)(aq), YbUU(aq) and S«(II) <aq) with 0B, 0 2 , bfco" , N0~ , H0~ , H ^ , UoZ , BrtC and CloZ , and their disappearance rates i n water were deteraiaed. Froa these data the reac t iv i t i e s of the reduced metal lona were evaaincd froa the atandpoint of providing a possible basis for distinguishing, between inner and outer sphere electron transfer nccbeaisas. I t i s suggested that the react iv i ty of Eu(II) and Yb(II) nay be interpreted in terns of an inner sphere aechanism, in agreement with J.P. Csodlln e t s l . ( 2 '

In argon-aaturated neutral solutions of Tb(III) the absorption spsetrua shoved a r i r l " " around 285 na. Hie seat spectrum was found with ifjO-eatUratad Tb(III)solut ions, but the opt ical density a t 285 na was twice as great i n H20 solutions as in argon aolutiona. I t can therefore be concluded that the precursor of the transient abaorption at 285 na i s the OH radical . One aight be tempted to assign th is absorption to the Tb(IV) result ing froa th* reaction of OH radicals with lb ( I I I ) . References:

1. T H O U , A. e t a l . , J. Chen. Pays. 42, 3366 (1965) 2 . CANDLIII, J . P . , J . An. Chca. Soc. 86, 1019 (1964)

EFFECT OF POSITIVELY CHARGED IONS ON THE HYDROGEN YIELD IN THE RADIOLYSIS OF AQUEOUS SOLUTIONS: M. F«W-

the radiolytlc hydrogen yield (L, va* measured la gazna Irra­diated deaerated iqueous solutions of seta! lona known to react very efficiently with e" or H atoas. Xn T1(I), Ni(II), Co(TI), Zn(II), Eu<III), lb(XXI) and Sm(III) solutions, G^ was constant (Cg - O.4J+0.O2) and no solute concentration effect was observed up Co 0.1 M. In Cd(I?>, Cu(II), Pb(il) and Ug(II) che value of G^ decreased with increasing solute concentration and the order of efficiency of these netals in reducing the G^ was Cd(II) < Cu(H) < Pb(II) < Hg(H). The value of Gg was also measured in solutions containing various concent­rations of NO3 -1- T1(I); the hydrogen yield found was the sane as in che absence of T1(I) ions.

"The fact that all these cecal ions are good scavengers for the reducing species leads to the conclusion that e~ or H atons are not the main precursors of molecular H_. The dependence of GL on solute concentration fits homogeneous kinetics, and it is suggested that the precursor is a species which could react with water to give molecular hydrogen. This could be H~ produced by the reaction of subexcitation electrons with water,as proposed by Flatzaan .The reactivity of the mfttal ions towards 11 seems to be governed by the rate of substitution of _ a"

11 on Che aquated metal ion. All the netal ions that nave no effect aq H

on CL have a specific rate constant for ligand substitution k < 108 H*"1 sec"1. The others, i.e. Cd(II), Cu(II), Pb(II) and H g U D , have k, >, 2xl0 8M~ i see - 1. Moreover the relative reacclvicy values (2) found are in good agreement with the kj values found by Bigen .

Kafarancea: 1. PJATZMaN, R.L., Proc. 2nd Int. Congr. of Radiation Research, Harrogate,

North-Holland PuM. Co., 1962, p.128 2. EIGEN, K., Pure Appl. Che*. £, 97 (1963)

PHYSICAL AND INORGANIC CHEMISTRY.

Research during the period reviewed continued along the lines pursued in previous years, concentrating on electrode processes, non­aqueous solvents, thermodynamic properties of electrolyte solutions, and reactions in sprays.

Studies on electrode processes included investigation of anodic dissolution, anodic Films, electrodeposition of In and Co , electro-catalytic oxidation on platinum electrodes., electrolysis of nitric acid, double-layer problems, and polarographic reduction of chlorate.

Non-aqueous solvent studies were concerned with both organic solvents and molten salts, and dealt with solvent extraction, reactions of solvent membranes, ion-exchange membranes, anion exchange of metal complexes, recovery of uranium from phosphoric acid, and mixed complexes of Ga and Al .

Several aspects of the thermodynamic properties of solutions were studied, including molal volumes in mixed salt solutions, and accurate determination of water pressure lowering in the range of 10-100 u.

Reactions in sprays were applied to the production of metal and metal-oxide powders.

In addition several other topics were studied, such as the higher oxidation states of Am, the separation of Pu-238 and U-237, and preparation of U0 and its properties.

PHASE SPACE THEORY IN CHEMICAL KINETICS: A. Cohen.

The staple model of Ciouaousis and Stevenson for lon-colecule reactions was modified by Light^ to include several channels. The cross section for each channel was made proportional to the phase space available to that channel. Light 's theory could be extended to include endothermic reactions and, contrary to the nodel of Giourajusis and Stevenson, could explain maxima in cross sections as functions of energy.

We have developed a computer program based on Light's phase space theory for three-brjy ion-molecule react ions . The progran predicts cress sections for p-.oduct channels as well as cross sections for each "Horse" vibrat ional level in the product cnannel.

The four-body space cannoE be solved analyt ica l ly , and the exact numerical solution would consume too nuch computer t i n e . In order to overcome this problem, t r i a l s are under way to re la te the rotations of two diatomic molecules and thus reduce the four-boJy systen to a quasi three-body system, the solution of which is known. References: 1. GIOUMOUSIS, G. and STEVEMSOii, D . P . , 5 ,Chen. P h y s . , ,29, 297 (1933) 2 . UGrIT, J . C . , J . Chem. F n y s . , 4 0 , 3221 (1964) 3 . PECHUKAS, P . , and LIGHT, J . C . , J . Chee . P h y s . , 4 2 , 3231 ( I V J J ) 4 . PECKUKAS, P . , LIGHT, J . C . , and RANKIN, C , J . d iem. P h y s . , 4 4 , 794

(1966) 5 . LIGHT, J . C . , a n d LIN, J . , J . Chea. P h y s . , _*-J, 3209 (1965) 6. UOLF, F . A . , J . Chem. P h y s . 4 4 , 1619 (1966)

NEGATIVE ION - NEUTRAL MOLECULE INTERACTIONS BY PULSED METHODS: 1. Plaizner, G. Levin and F.S. Klein '

Negative ions can be produced by dissocia t ive attachment of electrons to neutral molecules at electron energies between 0 and 10 eV. The ions formed by th is process usually have an excess of energy, which i s mainly kinet ic and ranges between 0 and 3 eV. The excess energy resu l t s from the difference between electron a f f i n i t i e s and chemical bond strengths .

The primary negative ions formed by dissociat ive electron a t tach--(21 ment to SO- are SO , 0 and S • ' . In addit ion at leas t two

secondary lone, SO " and SO~ are a lso forced. In the present work a method waa developed for the accurate measurement of the reaction ra t e s of the charge exchange:

WBijmin Injiiiuta of Scltnca. R«hovot.

*0~ + *>2 • K>j" + *0 U )

ami tarn leermolecml* reactloa:

*>" +- *> 2 • »0j" + * (2)

time* 0~ is tarsal' la the H M n K p r radon as SO* (at .6 aV), It caa alaa ceatrlbete to taa SO~ formation by charge exchange between 0* aad SOj. aUa xeectlom aaa therefore atadlad independently by aalag 0~ loaa tutmed 'torn » 20 at 2.3 eV, although thai* ion* have a somewhat smaller eaergy excess tO~(M20) - 0.65 aV; 0~(S02) - 1.1 eV]:

0"(«20) + S0 2 • S0 2" + 0 (3) The loa aouxce of a magnarlr aactor aaaa opoctroaater (Atlas-CH4)

C3 4) waa modified to oparata In a pulaed mode* ' ' . The negative inna vara prodmced by a abort aenare alactron pulae of about :0.2 asec, and vara tbao allovad to raact for a controlled period <of 0 to 1 liscc) nidi neutral molecules praaant in tba loa source, which la essent ial ly f i e ld fraa. At tba and of tbla pariod a pulaa vaa appllad to an ion repeller to accalarata the primary aod aecondery lona into tha analyaar and aaaaura thair respective curranta. From the ratio of these currents as a function of the reaction time, the rate constants were obtained. Ik* following values «*re found: kj - 1«10""5 and kj - 8 » 1 0 - 1 2

c m ^ l ^ e e c " 1 . An upper l imit of kj - 5x lO" U c a ^ l ^ a e c " 1 wis calculated.

I t i s obvious that tha contribution of tha charge exchange reaction 3 to reaction 1 la qtilte aaall . Comparison of the two reac­tion channels 1 and 2 Ct,/k, ' 100) shows that at small relative energies -close to the thermal n a g * - charge exchange croea sections can be about two ordera of magnitude larger than those of ion - nautral Inter­actions. Similar results , in aaergy rangee between 5' to 200 aV, using Isotope l ibe l l ing , vara reported recen t ly" ' . Only very few kinetic data about these reactions at thermal energies are available at tha praaant time* ' .

HftrTIITTf' 1. H U l n , H.I.W. and MUCH, I .B .S . , electronic and Ionic Impact

rnaooeeae.Oxford University rreis , 1952 P i n t ad. , Chapter IV 2. D0MUI, F.H., J. Cham. rhya. 44, 3856 (1966) 3 . Coagtoa, » .» . and CsUfMnMOu, L.C., Phys. lav. IS* . 110 (1967) 4. DILLAID, J .C. , and RAMXII, J . t . , a t . a l . , J. Chaa. Phys. 4JJ,

2349 (I***), 4£, 23S3 <1*M), At, 3828 (19*9) 5. T0SI, D., Int. J . Mesa-Spectra and Ion Phys. 2 , 81 (1969) 6. STOXDAU, J.A.B., tttrKM, *.«. and UIJBAUIt, P.M., Thesis,

Oak Udge national Laboratory, 0UL-TM-25At, Hay 1969

KINETICS OF REVERSIBLE-CONSECUTIVE REACT'ONS. A COMPLETE MATHEMATICAL SOLUTION^): M. Gazith and M. Zangsn.

Hoik, vas completed on development o£ a method for treating kinetic data involving a three-stage quilibriun mechanis*, A ^-* B *£=* E *==* ? , and four differential f i r s t order rate equations. The experimental work and i t s mechanistic and kinetic interpretation were reported

(2) previously ' . The wort quoted deals with the kinetics of the extraction of HgBr, from a liquid polyphenol phase into a molten sal t eutectic, at 150*, in the presence of KBr (represented by C in the reaction scheme above). A nechanisnt was postulated and the rate equations were solved graphically to obtain rate constants and

19? concentrations of the species involved. Hg - labelled EgBr, was used to follow the rate of change of HgBr_(A) in the organic phase.

- 2-In the molten s a l t phase the species HgBr,(B), HgBr,(E), and HgSr, (F) were present,and only the sum B + E + F could be determined.

In the present treatment the rate constants were derived from the kinetic data by least squares f i tt ing to an approximate exponen­t i a l function:

where A and A axe the concentration* of {Eg i n i t i a l l y and at equilibrium ( t - 50 sdn), both expressed as percent of A , kl la the assumed rate constant of the f i r s t reaction stag*, and b ie a constant. The kinetic data used ware those for [KBrJ - C • 0.6 molal

- 3 and A. • 10 molal. With the aid of the exponential equation values for A could be interpolated, and the rate constants were derived by numerical differentiation of the rate equations, assuming as pr*viou*ly < 2 ) that f ^ - ^ . at any time t , where * 3 and K are the equilibrium constants of the second and third at**** of the reaction, The rat* constant* obtained were checked with the kinetic data for G • 0, 0.06 and 0.02 molal and f o n d to f i t .

A complete mathematical solution of the four difieremtial rata equation* was obtained o* the baais of the rat* comatanta only, by the Laplace-Carson transform . A* a reault malti-expomeatial inttgrated equations v*r* obtained for the concentration* A, 1 , I and F, H I function of the time t and KBr concentration C . lmclvdlmg theoretical value* for A , • , I , I . Ih* inmmt beweea calculated and experimental data va* fommd to b* satisfactory, lb* method can readily be extended to a wider ramfa of mmltiat*** reversible-

-124 -

oMMCKtlv* reactions. The Method o£ calculation can alao b« progren-•ed, with or without nodificatiooe, on an electronic computer, for any values of the Independent variables A t t , and C, assuming that the sttdtanisa postulated holds within the rang* of condition* employed.

toftrwcM: 1. CAZITH, M. and ZWGBK, H., Israel J. Chem. I , 57 (1969) 2. ZsJKEM, M.» J. Hiys. Chem. 69, 1835 (1965) 3 . iWDICCIH, M.H. «od EQDIGDIHa, E.H., Conaecutive Chemical Reactions

(English translation), D. Van Sostrend Co. Inc . , N.J.,1964, p.44

MOLAR VOLUMES OF ELECTROLYTES,AND IONIC RADII; M. Gazith. The densities of pure electrolytes MX , where H»i*i, Na, K, Kb,

Cs, and X-Cl, Br, I , were brought to a common temperature of 25*C for aqueous solutions, Molten s a l t s , and s o l i d s . This was done in the case of aqueous solutions by extrapolation to the pure electrolyte using the Gregory-Bewton interpolation formula on the density data . Fi fused s a l t s the extrapolation to 25*C was done by applying the empi-

Ibe densities of the so l ids were taken from the_literature and were corrected for structure differences, Molar volumes for the three s tates were calculated from V. • — , where H, i s the molecular

p i (fomula) weight of the e lectrolyte . V ± for aqueous solutions was also calculated from Masson's equation, in the form

V i 3 ' 2 " *v V i W 2 " 3 1 - 6 S v " °

v!>ere *° Is the «cl«r volume of the e lctrolyte at in f in i te dilution u d S y I s the elope of the llnemr equation • " »° + S Cl/Z ; here C 1* the aolsr concentration of the electrolyte In aqueous solution. (Data arc tabulated In Kef. 4 ) .

Assuming that V_ In tlie pure electrolyte la aero, due to the small e l s e of the lithium ion*,wbich occupy only i n t e r s t i t i a l spsce p

the vslse* of V l l c l , V W B r , and V L 1 J are taken as the solar volumes of the anions Cl~ , l r ~ , and i " . Plotting the Ionic solar voluaes thus obtained f ro . a l l aourcaa against r , where r la ttie ?aullmg radius In the Ionic crystal , glvee • freight l i n e s , on which the data for fluorides and nitrates can also bs accommodated.

' 3be d o s s correlation obtained for Molar volumes calculated with extraeolated densities fron various sources lesds to the conclusion that audi extrapolations are val id , and the Intrinsic volutes of the ions thus calculated auggest a new standard atate - the pure

elec t ro ly te - which may be as acceptable as that based on inf ini te •dilution molar volumes. Various models proposed for the cocrelatXca between molar volumes and Ionic radii were tested (Laidler, Hepler, Mukerji, Gleuckauf) In view of the avai labi l i ty of calculated in t r ins ic molar volumes, which so far were hypothetical in nature.

References: 1. a. International Cr i t ica l Tables, Vol. I l l (1928);

b. GA2ITH, H., IA-1168, 1967, p.110 2. JAHZ, G.J., Molten Salts Handbook, Academic Press, N.Y., 1967, p.39 3 . Handbook o£ Chemistry and Physics, 45th Edition, The.Chemical

Rubber Co., 1964-1965 4. HAffiffiO, I I .5 . , and OKEH, B . 3 . , Tiie Physical Chemistry o£ Electroly­

t i c Solutions, Third Edition, Reinhold, a.Y,, 1958, p.361

APPARENT MOLAL VOLUMES IN MIXED SALT SOLUTIONS^: HI. THE RECIPROCAL AQUEOUS SYSTEM LiCINaN0 3 : J. Padova.

(2) { The enthalpy^ ' and free enerjjy

aqueous e lect rolytes are mixed hate been deterained for a number of (4) binary e lec t ro ly te mixtures . Six binary mixtures can be made froa

the four s a l t s LiCl, ilaCl, LiKO-, :iairO„. four of these nlxcares have . e i ther a common cation or anion,and tao are heteroionlc: LiCl-Ka^G and HaCl-LilJO-, The re la t ion between tlio s ix energy changes on mixing

(5> I s called the square cross rule . I t has recently been confiroed for enthalpy J and free energy in halide systemSjSnd j u s t i f i e d on the basis of Friedman theory and Guggenliein specif ic ion interact ion .

The aqueous raixtures U a C l - U C r 7 \ I laCl-Ka^ * 8 ) , UC1-UK0 3

( 3 ^ have already been Investigated. The volumetric behavior of various aqueous mixtures of litfO.-tiaKO- and U.Cl-*ialJO_ were investigated » t a constant molality r a t i o over a wide range of concentration. The mean apparent molal volumes 6 uere calculated and nay be represented by the expression

• v - +v + i * ^ 8 * l f Z + s i c + s j c 3 / 2 CD

' whtrs +° i s the extrapolated value of $ v a t i n f in i t e dilution, and the coefficients S. a n obtained by leas t squares f i t t i ng of Eq.( l ) to the experimental data. Results obtained for the iUKQ.-UHQ. system ar t shown In Table 1.

The resul ts obtained for tht LiCl-NaNO. system were processed for extrapolation of t o t a l molality in round figures, such n I n , 2 t , 3 m , e t c . TIi*. aqueous system Lii« 3-NaCl i s being investigated in order

- 126 -

to check th* crow square n i l* . Preliminary result* see* to indicate that I t doe* not bold for ay* teas containing the nitrate ion where Ion

(9) pairing may occur •

TABLE 1 Coefficient* of Eq.(l) for the aqueous aysten HaMOy-LlNOj

ItdOj mole fraction S l S 2

0.0 -0.262 0.0 0.13063 -0 .221 0.0 0.15»37 -0.2196 0.0 0.25629 -0.2407 0.0426 0.49762 0.0282 0.0 0.76047 0 . U 6 1 0.0 0.S5166 0.2430 0.0 1.00 0.4280 -0.086

inferences: 1. tUXHk, J . , i n IA-1190, p.153 <1969) 2 . WD, T.C., SMIS, M.B. and YODHG, T.F., J. Fhys. diem. 69, 1C6B (196B) 3 . C0VWCTOB, A.K., LILLET, I.H. «nd ROBIMS0K,-E.A., J. Phys. Chem.

42, 2759 (1968) 4 . H U B S , H.S. end SOBIHSON, R.A., Multiconponent Electrolyte Solutions,

rergaaou Prow, 19S8. 5 . lOOB, T.7 . , WD, Y.C. and KHAWETZ, A.A., Discuss. Far. Soc. 24,

37 (1957) 6. U H I T , F.J. and WOOD, R.H., J . Phy». Cham. 43, (12), 4292 (1969) 7. WIETH, H.E. and HILLS, W.L., J . Oiem. Eng. Data 13, 102 (1968) 8. FAD0VA, J. and AB8AHAHER, I . , Israel J. Chem. 3, 40 (1965) 9 . Sef. (4 ) , p.78.

DETERMINATION OF WATER VAPOR PRESSURE LOWERING OF DILUTE ELECTROLYTE AND NON-ELECTROLYTE SOLUTIONS IN THE RANGE 0.02-0.1 .MOLAL: S. Amdur.

A new method for determination of vater vapor pressure lowering In the s:«nge 10-100 Microns, with IX accuracy, was recently develops* . Ib i s t e about 5x10 - 5x10 percent of the vapor pressure of water at 25°C, which I s about 23.5 wa Hi. The method permits meesuroaHmt of solutions In the "missing" range between 0.02-0.1 molal. Below t h i s range Ideality may be essuaed and above I t the l sop les t l c method can be considered.

The method was f i r s t baaed on solutions of NaCl and r c l . Further rhorMmg with solutions of CaCl2 gave complete agreement. Additional determinations were then made of various 1:1 e lec tro ly tes , LaCl. ,and non-electrolytes, such as D-glucose and uree.

from the reaultB obtained so far, it seems ctiat the non-ideal features of electrolytes are quite different from those of non-electro­lytes in the range 0.02 J.l molal. It was found that, per mol of solute, D-glucose decreases the water vapor pressure sore than does urea. The reason for this nay be because the greater hydration of D-glucose decreases the concentration of free water in solution, thus decreasing the concentration of nonomolecular water which is assumed to be in equilibrium with the total amount of free water. For electrolytes, the opposite effect was found. Lad., which is strongly hydrated (at least twice as much as NaCl) would he expected to decrease the water vapor pressure by a factor of 2 or more compared to solutions of NaCl (LaCl- has twice the number of ions per vol). However actually, the decrease was only by a factor of about 1.5. Apparently electrolytes influence, by secondary effects, the structure of water so as to push the equilibrium toward an Increase in the concentration of the more volatile species.

Reference: 1 . AMDOR, S . , J . P h y s . Chem. 7£> 1169 (1969)

RELATIVE STABILIZATION OF THE HIGHER OXIDATION STATES OF AMERIC1UM: M. Givon, Y. Marcus* and E. Yanir.

The experiments to s t ab i l i ze Am(IV) in phosphate solutions were completed. A yield of >995 pure Am(IV) was produced in H_PO,>10M by improvement of the e lec t ro lys i s process. The following measurements prove the existence of the +4 s t a t e i n these solut ions:

(1) Absorption spectra. The new bands correspond to those f2)

published for Am(IV) in fluoride solutions . They are not shifted bands of Am(VI) because Am (VI) produced by dissolution of KAm0 2CO 3 in fe^EOflOK •hows the familiar bands of An (VI), (e.g. 996nii)

(ii) lo dome trie titrations of oxidized solutions of An (in) in HgPO^lOH indicated a one-electron transfer (An (IV) + • -•• Am (Til)). MBssbauer effect experiments on the frozen phosphoric acid

. solutions shoved unexpectedly weak peaks for Am(IV)* Am(V) snd A*(VI), the strongest peat being due to As (III) in all cases. However, cnsaical analysis of the samples after the measurement* indicated the presence of the original oxidation state.

Htbrtw Ufltvmhy, JaniMhrn.'

-128 -

T W foraal potential, I f, of the couples Aa(rv)/As(III) and An<YlV«n(T> vera determined (see Table 1).

m u 1 fPl l f i rpT*"***1 o t ** l o n * asalnat standard

Conple [BjPO^I, 1! .Hydrogen E? E°(Ref.3)

•a(XV)/*nClII) U . 5 15.0 0.54 1.19 3.55 4.34

1.76 1.74 1.47 1.45 1.30 1.38

2.2

1.64

as lad lu ted by both theoretical arguments and experimental results , «n(VI) I s highly stable In the range 2.OH < H-PO^ < S.OH, pH < 1 Sulfate ions as Uganda s tab i l i ze An(Vl) l e s s than phosphate Ions. *»(V) I s stable In solutions of HjTO4 < 1.0H and in non-complexlng aolations at pH < 1.5 .

lefferencaa: 1. YBKX, E.> GIV0M, H., HA2CUS, T., Inorg. Nucl. Chem. Letters,. JS,

369, (1969) . JSrKI, L.B., and pnpjraKAN, K.A., Inorg. Chem. I , 134, (1962) . UXIMEK. U.K., Oildatloo Potential, 2nd. ed . , Prentice-Hall, Inc . ,

U 5 3 , p.311

ELECTBOCATALYTIC OXIDATION OF AMINES ON PLATINUM ELECTRODES. PART II. OXIDATION OF COPPER ETHYLENEDIAMINEW: I. F r W and O. Meyemein.

Preliminary studies using pulse radiolysls tschniques revealed th« exlatancs of Cu(lII)Ea2 complex. They also showed the trlvalent complex to be unstable, the copper oxidising I t s Uganda. The oxidation potential of Cu(lI)En 2 - Cu(III)£n 2 uai estimated at 0.6 volte vs . S.C.E.

Oxidation of Cu(II)Ia 2 proved possible on the platinum electrode. The rrtvelant copper complex did oxidise the llgaod, resulting in catalytic oxidation of ethyleasdlatiina. An oxidation potential of 0 .« volts v s . g.C.I. for tiw above couple was measured from the v o l l — l l l c data, Extensive study of the current-potential curves sad tkalx depnmeence on pH and reagent concentration suggested three possible mechanisms for the catalytic oxidation of ethyleaedlaalne.

* HSHWM IMlMrilty.-JmiMMm.

- 129 -

Etch of these •echsnlss* operate aider different experisKntal conditions.

lhi* represents the f i r s t reported ca*e on catalytic oxidation waves- The proposed aechanlsa throws l ight on several catalytic reduction processes and affords an Independent tool for the study of odd-valence lona In solution.

Reference; 1. FRIED, I . and MEXERSTEIK, D„ Israel J. Chen. l_t 74? (1969),

Proceedings

ELECTROCATALYTIC OXIDATION OF AMINES ON PLATINUM ELECTRODES. PART IN. OXIDATION OF NICKEL ETHYLENEDIAMINE<,>: I. Fried", M. Wilmertdorf* and D. Mayantain.

Nickel ethylenedlasine can be oxidised on platlnoB electrodes» giving rise to a catalytic oxidation save similar co that of copper ethylenedlamlne. Die oxidation potential of Ki(H)Ea_ - Ki(UI)Ea 3

la 0.6 V vs . S.C.Ej die nickel coaplex i s sore easi ly oxidized Chan the copper. The saae result vas observed for hoaogeneous oxidation of Hi(II)En_ by peroxydlaulfate ; while the nickel cosplex vas readily oxidised by this reagent, the copper coaplex did not reset.

Preliminary pulse rsdiolytic studies of the oxidation of Ni(II)En 3 shoved that Ni(III)En_ exists and i s unstable, oxidizing the Uganda.

The dependence of current-potential, curves of nickel etaylen*-dlaattne on pH and reagent concsntration shows s lai lar behaviour to that of copper ethylenediaalne, with auch difference* as at* dictated by the nature of d , d and d ions. References:

1 . FRIED. I . , W1UBRSD0RT, H. and MEYERSTEIN, D . , I s r a e l J . Chea. £ , 75P (1969)

2 . BOUCHAL and HRABAK, C o l l . Czech. Chem. Coast. 4 6 5 1 , , 3 1 , 1966

THE POLAROGRAFHK REDUCTION OF CHLORATE CATALYZED BY MOLYBDENUM TUNGSTEN MIXTURES*1) I. Hoosra.

Molybdenum and tungsten specie* in solution interact strongly with each other^causing the occurrence of catalytic chlorate reduction currants which differ greatly in Bagnltv.de from the Individual currents expected frost separata molybdenum and tungsten ion*. Tour peaks can sa observed on the poiarograms of. the aixtvr*. The first peak occurs at a potential specific to the Mo VI + Ho V reduction. Enhanced catalytic

act ir lcy at ta le peek la actrlamtaa to the formation a t a s Intermediate hating tha ceaeeeltlea (aV.O^j), * *>**" • *•» catalyt ic currant at tka m e a d peak l a alaa eaaaaced, kaeanaa of a redox Interaction between Ma 111 and inndanitafesaofara. At tha potaatlal of tba l a s t two peaks tka free reaacciea of moljUaama ia Inhibited by tba presence of aa aeeecbed layer of xeeacee psoedomatotumgetata.

J . nODAaA, I . , J . I lectroaael . Caen, ( l a press)

THE ELECTHODEKaTnON OF I N C H U M C ^ : R. Rahniotf.

Indium may be eleetrodepoalted from a d d ' or elkallne (7-9) aelatloas nalng various conplexing agents to prevent the p r e d p l -

tatloa of ladlon hydroxide. The indium coacentrxtioa la usually higher than 20~ M. In the present work the electrodeposition froa extreaely d i la te aolotlons containing aa l i t t l e as 10" M Indium was carried out uclag high curraot dens i t i es . The deposited and residual indium were determined using In tracer and measuring the act iv i ty of the solution before and after electrodeposition. -In was aeasured using a Kal crystal in conjunction with a aultlchannel analyzer.

The influence of the folloTlng factora on the electrodeposition of Indian were Maaured: pH, cathode-to-anode area rat io , cathode current density and indium concentration.

On the basla of the experimental raaulta the following conditlona era reconaanded for the electrodeposition of Indium from solutions in tba range lO""1 to 10 H; sulfuric add solution at pB ?.', cathode-to-anode area ratio 1:3, cathode currant density 1.2 - 1.8 A/cm , temperature 50-60 oC, addition of traces of ge la t in aa a col lo id , and whan necessary, Cm. ),S0. aa a conducting s a l t .

jefereece: 1. XArAELOFF, « . , Israel J. Chen. T, 78 (1969) 2. UUTAHOFF, « . , ladlochan. Kadloanal. l e t t . 2, 93 (1969) 3 . LIMOtD, H.I. , Trana. EUctrocban. Soc. , 79, Preprint No. 12.187 -

{mu. *. ma J.I. J r . , KMM, T.S . , U.S. Patent, ,2 ,*5M3t( l»«*) 5. LOVUCIK, 1 . , lOIIOTAC, T . , J . Uectrocnea S o c , j£9_, 127 (1962) 6. OCOGAaOT, T.H., ZAJROatVA, 1.1., ZYAILOTA, I .A. , Zh. Frik.

O l a . H, 1376 (1H2) 7. saaaMTJt, I . , Alia, > . , flnaka Xemletssmfuudeto Kadd. 65, 95 (1956)

CA. H , 11M7 (1962) S. ZAITtrT, T.T., TITOT, r . S . , C.A. JS8, 8637 (1963)

.9. TBMUOtk, L .S . , tkUKWMO, H.A,, C.A. 66, 11826 (1967)

- 131 -

THE MICROSTRUCT'JRE OF THIN ELECTRODEPOSITED COBALT AND COBALT-PHOSPHORUS FILMS: U. Admon.

Tha formation of cubic and hexagonal phases ID elecercdeposited Co-and Co-P thin fllma vai examined with the aid off an electron sicrc-acopa. The affect of pH, hypophosphate ion concentration and various substrate* on the relative abundance of theae phaaas and their orien­tation vaa determined qualitatively. Further work is being carried out to establish quantitatively the interrelation between phase abundance and magnetic properties on the one hand, and the above parameters on the other.

SURFACE TREATMENT OF ALUMINIUM 2S: B. Herman. Several chemical and electrochemical method* were triad for

producing a protective layer on eltsKinlum 25 need on the cases of electronic instruments.

The possibility of using electrolytic an«n<»n«g vas studied. The method consisted of : a) chemical polishing in a solution of 651 HN0 3 nixed with 752 HgPO^ (7:100 v/v) at 95 #C, keeping the density at 1.66 - 1.70 g/cc; b) anodic oxidation in 151 H^SO. (for a transparent coat) or 301 H-50, (for a non-transparent coat} at room temperature, using lead as the other electrode* with a current density of 15 ha/cm i c) pore sealing by the standard method of immersion In boiling water.

The chemical polishing prior to the anodlrlng gave MM good results as electrolytic polishing.

A NEW ELECTROLYTE FOR THE ANODIC DISSOLUTION OF REFRACTORY METALS: A. Aladjsm and K. Werntck*.

The electrolytes commonly used for the anodic dissolution of refractory metals are based on solutions of various ualida salt* in lover alcohols, e.g., ammonium chloride In methanol . Although such electrolytes perform quite reliably in the majority of applica­tions, there are special cases 1* which the use of hallde salts is mot desirable for various reasons, e.g. corrosion of almmimiu* contai­ners, reactions with various components of toe system, etc.

Nitrate loss bava a strong paaslvetlsg effect, amn foe this reason have found no use aa electrolyte* far the s—die dissolution of metal*. The cemmos belief, bases oa data oatalmaa with asjuaoss

• VWtiniSclantiM.

-132 -

systems, was that aaodle polarisation In nitrate solutions would result la surface oxisatlem ratter than dissolution, of th« refractor? •teal.

Z A am attempt to develop hallde-frae electrolytes for anodic disoolntiom, a large member of solutions of Inorganic aalta la methaaol vara tested. Contrary to expectation*, tantalum, niobium ana tnegstam readily dissolved la 5-107 aolutlona of ammonium nltraea la aataaaol* at room temperature, upon anodic polarization at an applied voltage of 3 volte or mora. The dissolution current density

2 conld be rained to 150 mamp/dm , without any evidence of paasivatlng effects. The current efficiency for dissolution was practically 1001 i.e., the dissolution rate corresponded to the rate calculated on the oasis of Faraday's laws. Preliminary data Indicate that the solubility of the metal complexes In the nitrate solutions is comparable to that in halide solutions in methanol.

The ammnalun nitrate solvent has been used by us for the dissolution of tantalum for analysis (It eliminates the naed for decomposition of the oxyhalide product obtained as a result of dissolution in aalide solutionsv ' ), and for the surface pollening of refractory metals prior to anodic oxidation In aqueous tartrate solutions.

Inferences: 1. ALaDJBi, A. and MAKDQW, D.J. Vac. Sc i . Technol. £ , <*)» 635

(1969) 2. ALUUZK, A. Anal. Chan. *1.(7) 939 (1969).

WORKING OF REFRACTORY MAGNESIA B0DIES*'>: S. Raviv, E. Rabinovitz.

Magnesia la c lass i f ied as an alactrlcal ly non-conductive material. Horsever, i t la known to be Insoluble in conventional solvents such as water, alcohol and various acids. It was therefore surprising to find that refractory bodias whose composition i s based on naiueai* can be worked vary conveniently by an electrolytic process In a selected so l ­vent system serving as e lectrolyte . The solvent ayatea i s a mixture of phosphoric acid, isobutyl alcohol and water, and the electrodes are Inert to Che electrolyte under the operating conditions. The body to be worked i s Introduced lato the electrolyte at an appropriate distance from the cathode and a unidirectional current la pasaad through the c ircui t , bringing about controlled local dissolution of the body* If dealred, two ox more cathodes commuted in parallel may be uiad. Uforenco: 1. JUVI*, s . and BABINOVITZ, I*, Israel Fat, No. C.29.339

in -

SYSTEMATIC STUDY OF THE NATURE OF ELECTROPlERCING AND CUTTING OF METALS J. Brandsteiter.

Following the successful development of a method o£ plsrcicg and cuctins various materials la en electrochealcal system * J,.« systematic study of the nature of the processes Involved has been started. There seeoa to be evidence that core than staple spark-erosion la involved In thla kind ot machining.

Some of Che interesting features that have so far eserged frco Che study are summarized below;

a) Many unusual electrochemical reactions, which can possibly find gone applications In cheaical processing, take place.

b) Shaping of the end of a tungsten rod. used as the negative electrode, into a sharp pin or into a. snail sphere, can be achieved in a matter of seconds.

c) Micro-spheres (1-100 \sa diameter) of platinum and other materials can be produced.

d) Cutting out pieces of various shapes from metallic sheet by electrochemical neaos, while preserving the tutrix sheet as veil as the piece cut out, seems feasible.

e) The technique could provide a simple and versatile means for doping, as well as far special electroplating ( a kind which haa been called "•etaUidtng").

References: 1. RAVIV, S., RA3IN0V1TZ, E. and HALKtELY, S-, J. Kucl. Hat. 31,

'30Q (July 1969) 2. .RAVIV, S., RABIH0V1TZ, E., private ccemmnlcatlons,

PHENOMENA OF CORROSION AND CAPACITANCE: S. Ravtv and E. Rabinovitz. Corrocion cauaea metals and alloys to return to their original

•tat* of oxidaa through * rhythmic process of capacitor chart* *nd discharge. If the capacitor discharge 1* homogeneous on the surface, cba corrosion la homogeneous, but If tha discharge occur* at certain points oo tha metal, thie farimgt about pittimg. Intercryetal corrosion la brought about by a dlacharga oo tha crystal fringes, end intsrfscial corrosion la caused by a discharge on the Interfaclal contact of iMtala.

The catholic corrosion of some types of stainless Steele wee studied by the rhythmic charge and discharge of en Interfeclal capaci­tor. The rhythm was achieved by cathedic polarization in aitric acid •ediua. The transfer from the passive to the active state gave poten­tial jumps between -0.3 and +1.1 V (vs. SCE).

-134 -

Ike ef fect of MM e lec tro lys i s p m a t i n a u studied and a l i l i r m aes fmad M t m » the rata of cethodlc corroalon u d the f r i s s ia ty of the capltaaca charge and discharge.

l e e ta lraa lc eorramtem of the natal couplaa etalnleee s t e e l -eraaiae, alaafalaa-exaeiaa, and i lrconiua-unalva was studlad,aad the axtaat of corrosion was show to ba proportional to too energy genera-tad by tee capacltaaca diecbarge and l t a frequency.

Flcetag corroeioo was studied on special eqaipaent vbich allows taa concentration "t tba electron flux at a point.

Tba current which pasaaa through tee c ircui t on Jauieraioa of tha spociaea studied In an e lectrolyte a t a certain distance froa tbt cethodscaeees loca l corrosion, tba extant of which could b« ragulatad by "*i»"y*t varioue paraaeters, for cxaeple tba solution concentration, l—jirratgre, type and configuration of electrodes, corranc danslty and voltage.

neferonca: 1. laYIT, s. and HAIMOVITZ, E., Journeee d'autonne, da la Soc.

Freacalse da Hetellurgle, Paris, Oct. 1969

THE DOUBLE LAYER. VI. ELECTRICAL ASPECTS*'': S. Rem.

Tbls ma tba l a s t of a series of publications on this sub]act. lba asrhsnlna of a l tctrolys la and ths oignlf lcanca of th is type of oator alactroa layar configuration In a nueber of s ituations vara coaeldersd. Iomlxatlon pbenoaeoe such •» plaaaa generation, and alsctroaegeatlc effecte,were discussed, aa v a i l as analog capscitat ivs c i rca l t s . «a explanation of now certain pairs of alanents can bacons e lectro lyt ic capacitors, sad the e f fec ts of taaperatura on the charge and discharge rates of each couples, vss given, an underetandlng of ' the ahsniajeaoti can abed aore l ight on nata l l l c corrosion, anodic and catnodlc dsposltlon, sad other electrocbaalcal reactions.

B t l T s M f 1. U t i r , J . , ketaex Corroslsa Industrie *fc, 521, 36 (1969)

- 1)5 -

QUANTITATIVE GAS CHROMATOGRAPHIC ANALYSIS OF GASES EVOLVED IN THE

ELECTROLYSIS OF NITRIC ACID: Y. Auaf.

Mixtures of H_, 0 . , « , , N_0 aud COj collected from the electro­lyt ic process were analysed with a Hevletc-Fackard Gas Chromatograph (5750A Series) f i t ted with a duml thermal conductivity detector and a GSV-11 gas sampling valve with 0.5 ml sample loop. An H-P digital integrator (model 3370A) uaa used for quantitative* analysis.

The column system was basically the one used by Bennett^ , but modified for the separation of hydrogen within a. 10 minute t iae l imit . The system consisted of 3 columns: (I) V6"t 0.250" 00 Cu, Porapak Q, 50/80 mesh; (II) 32*. 0.125" 0» Cu, empty; {III) 8*Iff', 0.2SO" 0D Co, Molecular Sieve 5A, 30/60 mesh. The columns were arranged in the sequence (I) - detector - (II) - (III) - detector. All the columns were at ambient temperature. The detector temperature t>±s 150* and current 250 aA. Carrier gas was helium at 50 psi and a flavrate of 50 al/min. The sampling was done by evacuation of the sample loop (through the GSV Inle t ) . The pressure of the sample within the loop could be measured with a manometer for accurate quantitative assessement of the Injected sample.

The above system was found extremely useful for large numbers of samples, since no equilibration of the solumos i s needed, and hence samples can be injected one after the other. Since CO- and KjO are adsorbed on column (III)* rejuvenation of the columns was performed at 200* from time to elm*.

Reference; X. BENHET, D., J. Chromatog. 26, 482-484 (1967)

A METHOD FOR SAMPLING GASES EVOLVED DURING ELECTROLYSIS: Y. Amf. Tb* usual method of collecting and measuring the volume of

evolved gaies l i by displacement. A gas collection tube of known volume Is connected to the top of the electrolysis vessel and f i l l ed with the electrolysis solution. The time taken for the evolvimg mw to displace the solution In the tube completely i s measured.

A simpler method which doM not necessitate the juggliag of tern solution batman the vassal ami tarn tuba wee developed. The •amallmg tuba make* use of a 4-way stopcock (Tig. 1) . * one-way flow raatrlceot (Flp. 2 ) , f i l l ed with a suitable liquid (such aa water) cape the top of

t j

PiC. 1 * ig . 2 Four-wey stopcock One-way flow raatrlctor

th l j sampling tube and a flow of helium I s Introduced Into tbe e lectro­l y s i s T M M I until the air above tbe lolutloa b » been completely displaced (this takes about 10 ain, as checked by fee chromatography). Electrolysis Bases then proceed to displace tbe helium. The flow of tbe cases evolved i s •assured by a soap-film flowmeter. The above arrangement permits stacking of several sampling tubes and collecting individual gas sample* at selected intervals by closing one stopcock at a time.

I t was found that without the introduction of helium, measure­ments vera reproducible after 20-30 mtn of e l ec tro lys i s , which i s satisfactory for collecting samples other than those evolved at the beginning of the e lectrolys is .

THERMODYNAMIC PROPERTIES OF ASSOCIATED SOLUTIONS OF THE TYPE: A+BfAajsmfA+BfABj+A/1^ A,Ap*IWst

Tbe mmis characteristics ot non-electrolyte mixtures can often be fair ly well described by the theory of ideal associated solutions. This theory can be applied to solutions where deviations from ideal i ty result from tbe strong Interactions between molecules. The formation of relatively stable configurations (associates) i s possible between either l ike molecules or unlike molecules and Is frequently observed where the components are capable of forming Intermolecular hydrogen bonds. Mixtures which can be characterized by self-association only (e .g . carboxyllc acids In an inert solvent) or by coaplexatlon only (e.g. chloroform + acetone) have been discussed in the l i terature, l a mixtures ot alcohols and fatty acids or of alkylphosphbric acids In polar solvents both effects are found. The present work deals with two type* of solutions. In-the f i r s t the nonldeal behaviour reemlts only from tbe association (coaple»elon) reaction t A + j s + AB , j > 1, ID the second type, complexatlon i s accompanied by the self-association of one component : A + j l + Al.[ rA + A r , r > 2.

The chenical equilibrium and the excess thercodynmic func­tions of nixing G , K , S , V^ and C were calculated as a function of the stolcltioaetric nole fraction x of the nominal component A and the equllibriua constants of the coneapondiog association reactions. Fox the first type of solutions, the extresnn values of the excess free energy and enthalpy of nixing C and H appear at at - 1/(1+}). 0 is always negative and b has the sane sign as the standard enthalpy of the association reaction AH°, which is usually negative. The standard reaction entropy AS , which is related to the loss of orientation of the molecules A and 8 when the complex Afi. is formed* is always negative. The excess entropy of mixing, S , may acquire any positive or negative value. For the second type of solutions the behaviour of the thermodynamic functions was ODserved to depend on the order of magnitude of complexation and on the self-association equilibrium constants.

120

, ' 1 i 1 ' 1 ' 1 - 1

- \ 2503'C -100 \ -

-BO -

X . | 60 - -

4 0 - -

20

1 1 1 1 , 1 , 1 J 0.3 0,4 Q6 0.8 mote fraction of C^COOH

Tig. 1 Total vapour praaiura of the aathanol-proplonlc acid ayata* at 25.03 C. Tha circlaa are axpaiiaantal point!; tha Una vaa calculated for tba

A + B + a, aodal with K - 0.523

Zn ordar to dataralna tha valuaa of tbt aqulllbriiaa conatanta and thalr taajparatura dapandanca, that coanactioa batwaan tha axcaaa thanodyaaaic functioua at infialta dilution, aa darlwd froai tha thaotj of idaal auocUtad aolutlona, and tha aapariaaatal date obtainad f w , gaai chrgMtaaraphic .aaaauraaanta, vaa atudlad. Tha

- 13B -

dependence of the Mutual diffusion coefficients and the surface tension of binary Mixtures on the association effect was: also consi­dered, the predictions of cue theory were compared with cue experi­mental data for * msaber of systems : diphenyl methyl phosphate + chloroform, 1-octanol + formic acid, methanol + propionic add. The results toe tbe l*at system are shown IK Fig. 1.

Vapour pressure determinations, gas chromatography, vapour pressure osmometry and solubility were used for the study of the association reactions In the above mentioned systems.

Reference: 2, ApaBLAT, A . Proceedings of the XII XUFAC, Sydney, 1969

MUTUAL SOLUBILITIES OF DIPHENYL PHOSPHATE AND SOME ALIPHATIC HYDROCARBONS^: A. Apetbtat.

Liquid-liquid coexistence curves for binary nixtures of diphenyl

•ethyl phosphate (DPMP) with u-alftanes (C--C ) and isopentane were

determined from -15* to 89*C. The solubil ity curves are very asymmetri­

cal . At a given temperature the solubility of the hydrocarbons In

DPMP can be arranged in the descending series n-C- > i -C g > C, > C_

> C g > C 1 0 , while the solubility of DPMP in the hydrocarbons Is

C10 * C 8 " C7 " C 6 * "*$ * 1 _ C 5 *

The solubility of the hydrocarbons In DFHP as a function of temperature can be expressed as

In x£ 2* - - &£&. + 3.754 - 0.284 n (n - 6,7,8,10)

„<Z)

lnx< 2> - - -2*^+1.5470 1 T

(n-C 5H 1 2)

(2) wftere x£ ' Is the molar fraction of component L (alkants) In phase 2 (DPMP), and n is the number of carbon atoms in the hydrocarbon chain.

The solubility of DPMP In hydrocarbons la

la x*1' - - 23S2 + 3.636 + 0.0505 n (n - 6,7,1

ta „ ( ! > . . 2 M i + 3 . 7 6 1 1 Cn-CjHjj)

ta»JU—2f* + 3.«3B6 (1-C5K12)

Analysis-of the WMP branch of the solubility curves shows that the excsM molar enthalpy i» almost the »«*• for all the hydrocarbone,

- 139 -

and the position of a hydrocarbon in the solubility series depends on the entropy term, which can be correlated linearly with the number of O L tegmenta in the chain. The solubility parameters of DPHP as well as the upper critical solution temperatures were estimated from the solubility data for the systems considered.using the theory of regular solution* (see table). Good agreement was found between the values obtained and those derived from vapour pressure measurements, which were performed only for the DPMP-hexane system (x - 0.65b and T - 417*K). c

TABLE 1

Solubility parameters of D7MP solutions

Alkane S 2 *e c

CS«1i. 10.3 0.712 442 c«*it 10.3 0.674 42t!

Vifi 10.5 0.638 457 c*ha 10.6 O.602 451 C 10 B 22 10.8 0.536 486

Reference: 1, APELBLAT, A., J. Chen. Soc. (in press)

GAS CHROMATOGRAPHIC; STUDIES OF SOLVENT EXTRACTION SYSTEMS. II. OIPHBNYL METHYL PHOSPHATE: A. Apslbht.

Activity coefficients and the excess thermodynamic functions at infinite dilution in diluent - DPMP systems ware determined using gas chromatography. The activity coefficients and the partial molar heats of vaporization AH for the systems considered are given In the table.

The behaviour of the excess thermodynamic functions In the DPMP + diluent systems is similar to that observed in the C^Hg + diluent systems but not to that of the tBp + diluent systems. This Indicates that the interactions between the benxene rings of DPMP and the diluent axe predominant. The central phosphoryl group in DPMP Is screened fro* the diluent molecule by the electronegative phenyl groups which reduce the electronic density of the pfcosphotyl oxygen. It can be expected that replacing an alkyl radical la a phosphate (if TIP and D T K are compared) by an1 aryl group will produce additional sttric hindrance between molecules of the diluent and D P * In the solution .

- 1 4 0 -

UJDKJUSm.

Ml.anT Activi ty c o * f f l « n t «

kcal /aoU Ml.anT

25*C 45'C 60'C 80*C kcal /aoU

•anna cyrlnhrr—*

tolaaac c n k g t tacxacaloclde cHorafoni accceae

lrfrT*nrT

etaanol IMEaT

5-83 4.07 1.00 1.30 1.39 0.428 0.905 0.827 1.43 1.71 4.77

5.01 3.56 0.98 1.22 1.35 0.461 0.882 0.816 1.31 1.51 4.39

4.57 3.29 0.98 1.18 1.33 0.489 0.877 0.808 1.26 1.40 4.20

4.14 3.03 0.99 1.15 1.32 0.S31 0.880 0.799 1.21 1.31 4.04

6 .1 6.6 7.9 8.4 7.4 8 .1 7.3 8.3 8 .3 9.0 9.7

EXTRACTION OF HCJ AND H£SOt 8Y SOLUTIONS OF TBIBUTYL PHOSPHATE IN CARBON TETRACHLORIDE, BENZENE AND CHLOROFORM''): A. ApalMat

2be extraction of B d in to aolutlona of tr lbutyl phosphate (TBP) in CO., ana C6H& (20-100Z T/T TIP) and in ch lorofon (80-100Z v/v TOP) n i atudiM, u m i l tk« extraction of HjSO^ into T8P + CC1, a l x t u r u (8O-100J » / » T » ) .

K)( , — i — i 1—i 1—i—| r

1.0 0« 0* 0.4 0.2 0

« 1 . 1 l a l a t l a l tetWM n t « concentration In tba binary (TBP + HjO) or tarnarr ftlf • »j0 + SCI; TIT + HjO + H2504; TIP + HjO + anOj) organic phaaa, and th« watar ac t iv i ty of tha corraipondlnf aqul l l -briiM aq/jaova phaaa

The result* uate compared with tho«e published for the eorrti-ponding extraction of nitr ic *cld. Good sgrceaact waa feted b«cvce^ data publiahad for undiluted TBS and tba raaulta of our experlaeats. A distinct diluent affect was observed la tba c u t of HCl In the systeas with C H, and CCl^, whereas with ni tr ic add no sueh effect waa obacrvad. Tbe accivltica of TAP were calculated over the racge 0 - 9 H aqueous EC1, using the Gifcba-Duhe* relation. The equll lbrlw constants for the interconversion of TSP-H20 Into TBP-EC1'4HJ) and Into TBP'UKO.-^O were esticated to be 0.064 mole/liter and 6.1 mole/liter, respectively. In both cases, the standard reaction entropy Is the dominating term In the standard change o£ free energy £G°.

Water partition in systems containing HC1 and H_SO. shows xarkedly different behavior from that in the BSO- + H-0 + TBP system (Pig. 1) . In the former the water content of the organic phase increases with decreasing water activity in tbe aqueous phase,, whereas in the la t ter , as in the binary- TBP +• H-0 system, water decreases with decreasing «=,/)* Reference: 1 . APELBLAX, A . , J . Chen. Soc . ( i n p r e s s )

SEPARATION OF ALKALI AND ALKALINE EARTH SALTS BY SOLVENT EXTRACTION: M. Gszith and M. Zangen.

The solvent extraction of alkali and alkaline earth sa l ts has not been studied as extensively as that of other leas cosaon heavier metals, although knowledge of distribution ratios and selectl.vi.cy of organic solvents towards these salts Is of considerable theoretical and practical importance* On the theoretical aide, such data are necessary for the development of a general extraction theory and for the study of extraction mechanisms and sal t log oue^ ' . Oo the prac­t i ca l side, i t should be posaibla to extract a rare alkal i such as lithium, present in aaall quantities In highly cooceotrated brines (such as the Dead Sea), with * suitable organic solvent, although 4

interference of Ca and KB le expected. Naturally occurring lithium has some important nuclear uses, and lithium salts In general have found several industrial usee.

A systematic study has been, started of distribution ratios aad se lect iv i ty of several organic solvents, such as butancl, isosentanol, •ethyl isobutyl ketone, triiaooctylenlna-bensena and Taf-hoataae, toward LiCl, KaCl, XC1, C«C1„ SrCl„ HgCI,, O r , and LUr, which are

(21 the components of a synthetic Dead Sea residual brims w » with a view

- t * 2 . -

b» ta* < i w l i n « t ef • practical prsceas of •elves* extraction of UtM'as salts frest Mtiml ceeeeatratee1 arises. Hetsoli save bees •evtltpi.1 fee eh* w e e sselytleal AttlMClea of ess asiou by tltri* Mtrlc eatasts, sf 4 * catlss*; rr;*toalc absorption ••ectropbotosetrr,, Ml se" MCMI —lastIf *y • * the solvates by ftwvlaecric aetfcod*.

Jsf^rssces.: 1. WOT, A.H. a*i KTOAIUCBBBCO, ftjisa.J. Inor*. Chea. 12,360 (1967) 2 . TOR, J . M i STILLnt, M., U-712 , (1962)

STUDIES ON AMINE SALT SOLUTIONS AT HIGH TEMPERATURES BY DISTRIBUTION A1WGAS CHROMATOGRAPHIC METHODS: J. David, M. Zansfn «nd A. ApeJblat.

The distribution of laO.~ between 1-cnloroaaphtJialene solutions of tUocjaaate s a l t * of various amines and a cutect lc Mixture of aoltcn •If-jH tniocranates has ba«n studied as a function of the aamoulu* aalt and serrhenate l o * concentrations and the temperature. The didodecvl-aouoaiea, dJoctylaaaimTii, tetra-a-pentyl samnn-fua and tetraisopentvl — n n l i i s a l t s were used.

Tne dependence of the distribution coeff ic ient D on the amine s a l t concentration vai found to deviate froa a s laple anion exchange • o d d . The deviation was interpreted i n term* of ion-pair inter­actions of various kinds. The distribution coeff ic ients were found to be an increaslflt function of the perrhenate concentration.

TABLE 1 aeO,** distribution at 170* between T1PASCH in chloronaphthalene

Md » * « * + KgCT autsct lc

[UO^'J » 2.15»10"* IJW)4"J - 1.036»10' 3 IR»04" • 2.16X10"3

coac. of TOUCH

(Mi 0

cone, or Tirtsa

(•) 0

cone, of TIPASCH

(•) D

0.001*7 0.00499 0.007W 0.016* 0.029 0.09*7 0.102 G.142 0.219 0.514

0.0013 0.00271 0.00335 O.OOMO 0.00790 0.0OM9 0.0197 0.0227 0.0333 0.094

0.00219 0.004*4 0.0444 0.1222 0.230 0.31*6 0.44*4 0.773* 1.118

0.0194 0.011*9 0.03199 0.0403 0.057 0.062 0.073* ' 0.079* 0.1019

0.005 0.0093 0.0164 0.0293 0 .0(1 0.261 0.624

0.0476 0.0553 0.069 0.075 0.0(47 0.106 0.116

- 1-S3 -

The activity coefficients and exscan therawdynaslc furxcic^j at Infinite dilution were doterained for Che above aemcnlua sales 4c temperaturea above 160"C, using the gas chrcmaEoarophlc sieehr-d. Determinations were carried out in the following diluents: tc t? i l l=c , chloronaphthalene, chlorobenzene, dodecane, •-xylene, o -zy leu . The activity coefficients were found to decrease strongly with the polarity of the solvent. The results may be interpreted la terau of the toe-pair interactions Mentioned above.

OSMOMETRY MEASUREMENTS OF 1-CHLORONAPHTHALENE SOLUTIONS OF VARIOUS AMINE SALTS AT 100°C: J. David and M. Zangen.

Osmometric measurements were made of the lowering of the vapor pressure at 100*C in 1-chloronaphthalene solutions of tetraisopentyl-aBnonlum thlocyanate, tetra-n-pentylarooniua nitrate, didodecyl-asmonlum thiocyanate, dioctylamnonlus thiocyanate, didodecyl? aoniixi nitrate, dioctylaamonlun nitrate, didodecyla&aonlun perrhenate. the sane measurements were also made for mixtures of various proportions of didodecylasmoTiluB thiocyanate and perrfaenate. From the osranaetric data, the foniation of different oligomers was evaluated, assudng the positive deviations from ideality to he due to association only and that the activity coefficients of the various oligomers remain constant.

The tetraalkylammoniua citrate and thiocyanate were prepared from the corresponding iodides by anion exchange on Amberlite IRA.-600 resins . The secondary amine sa l t s were prepared by equilibration of ether or benzene solutions of the amines with aqueous solution* of the corresponding a d d s . All the salts were lecryttall ixcd from ethyl acetate to constant meeting* The osmo-macrlc measurements were made with a Kecarolab osmometer, Hodal 302-A, at 100*C. The aoluta concentration ranged between 0.01 and 0 .1 molal, Triphenyl methane or triphenyl amine in l-chloronaphthslene wmre used aa reference: standards.

Assuming an activity coefficient of unity for the aggregates, the total concentration of the amine s a l t i s ( Ives by B - & * n * a t where n i s the number of monomers, in the aggregates and 8^ la the

' overall s tabi l i ty constant of an aigrfgate of a monomers. To*, concen­tration of species present in the system as determined experimentally can be given by S - 2h n* , and the average number of monomers In a series of multinera la given by the relationship n - B/S. from these relationships the overall s tab i l i ty constants S verm calculated by

- 1 4 4 -

* "-rrir leatt •*.•.»• txagam naiaa. * digital coaeiitar1 ' . lb* raaelta a n ftvw ia dw taHa.

IMUlltT a n i i M i B for the aaliia lalta In l-chlorooaahtaalana * at ioo'c

tetralaoeeatylaMonliai tblocyaaate B 3 - 4098; B,, - 3 . * x 1 0 3 ' tetraaeatyl anaimiiai nitrate B 3 - 3447; Ni - 3.8 x 1 0 3 1

dUodceylaaMoaiva thiocyanate B 2 - 12.96; 6 I - 3970 dlriodacylaMDaiom nitrate S 2 « 225.2; «, - 861.9 dloetylaafloaitai tblocranate B 2 - 115.1; "< - 4.35 x 1 0 5

illni [JIT—ii i t i» nitrate B 2 - 1.74 x 10*; 8 i - 1.29 x 10 7

dldodecjlaMOniw perrnenate B 3 - 385.2

leferences: 1. KEU05IS, L.C., EVE1S. E.C. and OtAUS, C.A., Proe. Natl. Acad.

Sc l . 48, 121 (1962) 2. HAirOWITS, G., Ph.D. Thesis, Jerusalem 1969

MIXED CHLORIDE-BISULFATE COMPLEXES OF GALLIUM: M. Zangen and R. Rafaetoff.

The object of this work vas to ascertain the nature of the gallium. species obtained In the separation c* Ga fro* other group III elements by extraction froai a d d sulfate-chlorlde solutions .

The partit ion of tr iraiaat gallium between, me thy l e thy Ike cone (HEK) or wsthylis obutylketone (SHBK) and aqueous chloride-bisulfate solutions of coajtant ionic strength ( - 5,0) was determined radiometritally as a function of the acidity of the aqueous phase and i t s chloride-biaulfate rat io . A pronounced maximum wat> found In the distribution ratio at 2-3 M chloride.

Comparison of the ultraviolet spectra of G* in the organic phase, obtained after extraction from sulfate alone, chloride alone and sdxed chlorlde-blsulfate, clearly showed the existence of mixed complexes of Ga in the organic phase.

The experimental results can be -Interpreted in terms of the formation of the' following complexes In the organic phase, where KtH represents a Icetone-solvated hydroxonlun Ion: XtH+*GaCl4, Ktf*-Ga(HSO£)^f KtH^'GaCl^HSO^, (KtH+) GaCl^HSO^)*" -

Th« formation constants, K, g , K , , K_, and K, , , rt*p*cUvcl?, haw the valuta given In Table 1.

TABLE 1 FomatJon constants of gallium complexes

HEX MIBK

l o S K 4 0

K>8K2/,

- 1 . 8 + 0 . 2 - 0.4 + 0 . 2 - 0.1 + 0 . 2 - 3.2 + 0.2

- 1.6 + 0.2 + 0.5 + 0.2 - 0.5 + 0.2 - 4.2 + 0.2

Reference; 1. MTLiVES, G.W.C.. Analyst Si , 367 (1956)

KETONE EXTRACTION OF MIXED CH LOR IDE-B (SULFATE COMPLEXES OF ALUMINIUM, ANO INDIUM: B. Rafaeloff and M. Zangen.

The p a r t i t i o n of Al( I I I ) and In (HI ) between aqueous chloride— bisulfa te solutions of constant: ionic strength {" 5.0) ana! Eetayletfayi-ketone (HEK) or methylisabutylketoiie CMIHK) ^as Investigated radio-pe t r i ca l l y , as a function of the chloride-blsulfate concentration ra t io and the acidi ty of the aqueous phase. A maxima in the O-stribution r a t i o D was found for both Al and In around 2 H aqueous chloride.

The d i s t r ibu t ion r a t io waa found to be l i - - a r with the acidity of the aqueous phase In the extraction of Al with both HEK and MBK, and of In with HEK. The dependence of D on pH was less than f i r s t power In the MUSK, extraction of In.

The re su l t s can be interpreted l a terms of the formation of the -following complexes, where Kt represents ketone and Ktfi & kttooc-aolvated hydroxoniun ion:

KtH+"AlCl", KtU +.AlCl 2 (HSO^*, KtH + .Al(HS0 4) 4 .

KtH+-InClT, KtH**-InCl3 HSO , KtH^.InCl^HSO^, KtH+.InCl(HSO.)",

KtH+» In(HS0,)~ t InClJCt, InCl2HS04Kt, InCl(HS0 4) 2Kt and In(HS<>4)3Kt.

-146 -

ANION EXCHANGE OF METAL COMPLEXES. XVII. THE SELECTIVE SWELLING OF THE EXCHANGER IN MIXED AQUEOUS-ORGANIC SOLVENTS*" V. M m u * M B J. RHMRU

3ne swelling of Dovn-1 anion n c k a i | t r i crosa-linked vith 4 , 6, seal 16X DVB was M U W U i s i m n l organic aolventa and In mixtures of -frr— —l»eafe with water. Both tba chlorida and parchlorata Coma of that realm war* Investigated. In tba pura solvents tha availing of tfe* chlorfaV fora resins decreased i n the otdar vatar > f omemide > matfcomel > ethamol > acetomltrile > 1-propaool > 2-propanol > acetone > ditmcane. Toe perchloratc form awallad laaa i n a l l cases, with relatively high swellimg by foxnamide and dimethyl-formamtri'e. In tba mixed solvents the resin showed preferential sorption of one of tba solvents, the preference varying according to the condition*; In aqueous mixtures of propanol or ethanol, at low sola fraction* of the alcohol there was preferentlnl sorption of tba alcohol (especially in the percblorite raaln), but over most of toe composition range water was prafarrad. In tba amide and •ethanol nixturas there was l i t t l e pref crane* for either solvent. Host of the observed phenomena can be explained by the effects of the organic solvent on the structure of water outside the res in , and by preferential lon-aolvstion ef fects .

leferanca; 1. MUCUS, T. and M a m , J., J. rnys. Chan. 73, 591 (1969)

THERMAL REGENERATION OF ION EXCHANGERS: A. Kinrot and I. Michetfi* * The effective capacity of nixed bads of sons weak Ion exchangers

to take up salt from aqueous solutions Is strongly dependant on tempera-tur*. Such ion exchangers nay be used as working aubstances In desali­nation cycles Involving thermal regeneration*1'. The present work deals with the thermodynamic characterisation of these systems.

The equilibrium distribution of salt between the equeoue and resin phases was shown to be dependant not only on the best of adsorption and on temperature, as could be expected, but Sn other parameters aa well. It was found that a batter desalination performance la obtained at high ratios of rasln to solution volwnes and at high concentrations of salt in the ssuaous solution* The best systems for desalination art those which exhibit high buffering capacltlaa, i.e. large increases In adsorp-

* Htbrtw Unhwra!ty> J*ni«ftfn.

' * WttznuftinHituwufSckmet, RMiwot

- !47 -

tion par unit Increase in the chemical potential of the salt. Such hi^h buffering capacitiee can be expecttd In resins that undergo critical conformational transitions following the adsorption of aalt Ions.

It waa ahown theoretically that in certain cases it should be possible to reduce tha usual pE-titTation curves of a resin in various salt concentrationa to one "Master curve" isotherm ao that evaluation of thla resin as a working substance for desalination becoaes easier. This can be done by plotting the change in the chemical potential of hydrochlo­ric acid (instead of pH) against the degree of ionization of the resin. The method was checked experimentally for those resins that have already been tested for desalination . The results showed that while there is a significant reduction in the vertical intervals between the various curves, these Intervals do not vanish, and they consistently exhibit a reversed order ao that the highest curve becomes the lowest and vice versa. These results are attributed to the fact that an Increase In the ioniza­tion of our resins is accompanied by a slight Increase in swelling due to the greater hydration of the ionized groups and the counter-tons.

Reference: 1 . WEISS, D . E . , BOLTO, B . A . , HcNEILL, R . , M&CPHERSOH, A . S . , SIKDAX, K . ,

SWINTON, E.A. and WILLIS, S . , J . Water P o l l u t i o n C o n t r o l F e d e r a t i o n , 3 8 , ( 1 1 ) , 1782 (1966)

SOLUBILITY OF CALCIUM SULFITE IN SEA WATER: A. Goshen, M. Zangan ind A. Roy.

In previous work^ , i t was suggested that the problem of

corrosion and scale formation in sea water d i s t i l l a t i o n plants could

be solved by pre-treatment of the sea water with SO.. Since sea

water contains about 0.01 mole/l i ter of Ci , addition of SQ^ w i l l

lead to the formation of calcium s u l f i t e . While some data on, the

solubi l i ty of CaSO* in pure water are known (0.00041 mole / l i ter

at 30* and 0.00017 s o l e / l i t e r at 90*), no data are available for

fa ir ly concentrated e lectrolyte solutions. Experiments were there­

fore carried out to rtudy the solubi l i ty of CaSO. i n aaa water as

a function of temperature.

The following conclusions ware reached: a) tha so lubi l i ty of

CaSO- la several times greater in sea water than in d i s t i l l e d wattr;

b) the equilibrium solubi l i ty decreases with increasing temperature

(solubi l i ty at 25* - 0.0022 s o l a / l i t e r , at 35* * 0.0019 mole / l i ter and

at 45* - 0.0016 mole/ l i ter; c) as expected, ecutlibriuw i s reached

sooner at high temperatures (20-24 h at 25*, 10-12 ti a t 35* and

- 148 -

5-6 h at 45*); In other words,supersaturated solution* ar* lass stable at U ^ i i r taeperatmea; d) an Increase in pH leads to a decrees* In so lubi l i ty , by increasing the ratio l u l f i t e i b i s u l f i t e (in tht above experiments, the p!i at equilibrium i t 7 .4-7 .7) .

Reference: 1. aoT, A., in IA-U90 (1969) p. 161,162

URANVL NITRATE - ORGANIC PHOSPHATE EXCHANGE REACTION*1*: Y. Egozy and S.WML

lam. signal* of frac organic phosphates and organic phosphates bound eo uranyl c i trate are shifted relat ive to one another. In n i l cures of free and bound phosphates the signal* doe to both emi be simultaneously observed, provided the exchange reaction i s slow enough, Ihe separate signals tend to coalesce as the rate of reaction increases.

These effects have been ut i l ized i n a study of the exchange reaction between uranyl nitrate and tributyl phosphate, dibutyl cresyl phosphate and dicresyl butyl phosphate. Exchange t ines were evaluated by f i t t ing the experimental spectra to those computed with the exchange tine as a variable parameter. In this way the order of reaction, rate constants and activation energies ware obtained. Ihe influence of substltuents in the organic phosphate, and of different solvents, on the rate of reaction was exaalned.

Reference: 1. ECOZY, T. and WEISS, S., Israel J. Chen. 7, 6 6 p (1969), Proceedings

TRANSPORT OF URANYL NITRATE THROUGH SOLVENT-MEMBRANES: O. Kedem and M.S. Dariel.

Solvent-membranes have been proposed^ ' a n tool for hydrometal-lurgical separations. The solvent-membranes examined, containing alkyl

3 k or allyl phosphoric esters, showed very good selectivity (10 - 10 ) to the permeation of uranyl nitrate f roe solutions of nitrates of aluminlun and sodium.

In the present study mora detailed measurements were made of the stationary state flux of uranyl nitrate and i t s equilibrium distribu­tion coefficient with several esters . Distribution and diffusion coef­f i c i en t s , and hence flux rates , ware strongly Influenced by the subst l -tuent group* oa the solvents. The distribution coefficient (a) increased in the order: dicresyl butyl phosphate (DCB) < bis-(para-dlbutyl phos-phoryl)-methane (KETU) < dibutyl cregyl phosphate (DBC) < dibutyl benzyl

phosphate < dibutyl phosphoryl hexane (HEXA) < dibutyl phosFhoryl butane (XETBA). Values of a ranged from 50 to 1100 in 6ei tfsSQ,. The CXuxca of uranyl were of Che order of 10~ to 10~ moles/ca sec (foe 200 micron* thickness) and Increased In the order: HEXA * HETA * DCS < D3C. The difference In order compared with chat of Che a values reflects the fact that whereas the thermodynamic equilibrium can be fully defined In terms of the distribution and activity coefficients, the stationary state of a system with a gradient of chemical potential Is also dependent on the diffusion coefficient.

In the case of a temperature gradient, the additional Informa­tion needed to describe the steady state of the system is the thermal diffusion coefficient or the heat of transport, defined as the reduced heat flux per unit isothermal material flux. By means of a thercodynaaic analysis of the equilibrium distribution data heats of transport were obtained.

Reference; 1. BLOCH, R., FINKELSTEIN, A., KEDQf, 0. and VOFSI, D., Ind. Eng. Chen.,

Process Design Develop _6 231 (1967)

DIFFUSION COEFFICIENTS OF URANYL NITRATE IN PHOSPHATE ESTER SOLVENT-MEMBRANES: O. Kedem and M.S. Dane!.

The concentration and the temperature dependence of the diffusion coefficient of uranyl nitrate permeating througn solvent-membranes was investigated by a method using the kinetics of sorption from well-stirred solutions of constant limited volume.

Migration of penueants into the membrane i s considered to consist of one-dimensional diffusion into a slab limited by Infinite parallel planea. For a given system the concentrations are time- dependent' only, and determined by the condition that the total amount of solute in the membrane and the solution i s constant. This direct method i s often mote advantageous than the calculation of diffusion coefficients from quasi-stationary flux and equilibrium distribution data.

Solutions of Fick'a law for the present method have been given by Crank^ ' and by Carman and Haul ( ' . Since the diffusion and distribution coefficients are concentration-dependent the sorption experiments ware carried out in suitably chosen concentration steps. The membranes used were prepared f u i dibutylcreayl phosphate (SBC) and dicreaylbutyl

(2) ptioepnita (DC*)V p las t ic iwd polyvinylchlorida matrix reinforced with polyester fibers*

- 150 -

lam diffusion coefficients l n c n u i with increasing concentration —7 2 of mramyl In the membrane, sad are of the order of 10 cm / I I C and

10 cat /see for DCS and DBC, respectively. They alao increase several-fold on heating, from o* to 50*C.

Beferencct: 1 . fittlK, J . , Mathematics of Diffusion, Oxford University Pre**, 1956 2 . CAEiaa, P.C- and HASH., R.A.W., Proc. Roy. Soc.222 A 109. (1954) 3 . BLOCX, R.,FI«1XLSTDIS, A., 120*5*, 0 . , and VOFSI, D., lad. Eng* Chem.,

F r o o s . Design Dew lop. 1,231 (1967)

PURIFICATION AND SEPARATION OF PLUTONIUM-238 AND NEPTUNIUM-237: SA. Adar and A. Homik.

Ik ' tbe framework of Ma investigation aimed at the production of plutonium-233 for energy c e l l s by the irradiation of neptunium-237, •ctbods of separating the two elements were studied.

Preliminary experiments were carried out to control the valencies and s tab i l i se them i n the s tates appropriate to the separation processes to be used. The extraction of both plutonium IV and neptunium 17 from a n i t r i c acid solution by 102 trllaurylamine (TLA) in dodecane presents no special problems and fa ir ly good decontaminations from f i s s ion products are obtained. In order to effect a separation between the plutonium and neptunium, a valency combination Pu IV/Np V i s suitable, in which case the neptuniua remains in the aqueous phase and the plutoniua i s extracted. This valency combination may be obtained by heating the feed solution, made 1-3 molar in n i tr ic acid, at 90"C for one hour with 0.02 M sodiust n i t r i t e . After the extraction of the plutoniua, the neptunium amy be extracted with TLA by reducing It to Np IV by the addition Of 0.05 H hydrazine and 0.25 11 ferric ni trate , or alternatively, by the addition of 0.02 M ferrous sulphamate.

In order to increase decontamination and to affact a high con­centration, the organic phase containing the product (plutonium or neptunium) is passed through a "silax" column' J (silica gal containing a complexlng aqueous phase) and the actlnlde i s thereby stripped. A suitable complexing solution consists of 2.5 H ammonium sulphate, 1.0 H hydroxylamlne sulphate, and 0.25 M hSOy The complexed product can be displaced from the s i l i c a g e l by any aqueous wash and the s i l e x column regenerated by washing with the complexlng solution.

The above procedure can be greatly simplified by the use of

- 151 -

extraction chromatography, employing a column of Biatoport S (a sila-nised diatosiBCeovis earth) coated with up to 40% of Its weight of TLA. An aqueous solutiou containing both plutanium and neptunium is adjusted to Pu IV/Kp V valencies and passed through the column. The Pu IV Is extracted, while Np V and fission products remain In the eluant. Loadings of up to 5 g plutonlw/litrc column can be obtained with 133 coated absorbant. Decontamination factors from fission products are very high. The eluant is now adjusted to reduce the neptunium to the IV valence and passed through a second Diatoport-TLA column, where the neptunium is decontaminated and concentrated. Both products are ela­ted from the respective columns by 0.1 M smmonitai sulphate, 0.05 H HNCU eluting solution. Total elutlon is accomplished in approximately one column volume.

Reference: 1. KULTGREH, A,, in "Solvent Extraction Chemistry of Metals"

(eds. H.A.C. McKAY, T.V. Healy, 1.1. Jenkins, A. Taylor), MacHillan, 1963

PREPARATION A N D PROPERTIES OF URANIUM DIOXIDE: Z. Hadari and G. Decani. One of the most important materials in nuclear technology is

uranium dioxide. As a reactor fuel it is subjected to extremely severe conditions, which impose stringent requirements as regards structural and chemical properties, such as good stoichiometry, high density etc. In the present study, the correlation between the method o£ preparation of U0 2 and the properties of the product was investigated, in order to obtain a reliable method of manufacturing good quality sintered oxide.

Pellets of excellent chemical composition were prepared, with ao traceable impurities and atoichiometry better than 2.001 (analysis by polarographic determination of U ), The density of the pellets was investigated as a function of three parameters t sis* of granules of U0„ powder, pressure applied before sintering, and binder concen­tration. Of these parameters, powder siae proved to be the moat important, the best sises bolng 100 - 196 mesh. At low binder concen­trations the density-pressure diagrams •bowed a maximal, which disap­peared at higher binder concentrations.

The grain alee was also studied as * function of powder six* and pressure. Again, powder siae was the most important factor. Higher pressures tended to decrease grain sice, a tread much more pronounced the finer the powder wee. There was no dependence at all

- 152 -

on blmder concentration. Homogeneity of grain s i c e was good, but a sudden jump in s i ze near th« circumference of the pe l l e t , coJld not be eliminated.

Small f issures were found in the pe l le t s when the pressure was too high and binder concentration too low. Using the correct proce­dure* however, produced quite perfect pe l l e t s . A typical pel let i s 8 sat in diameter and 8 sat high, with a density which 1B 97X of the theoretical, and a grain s i z e of 70 - 100 iu

RECOVERY OF URANIUM AS A BY-PRODUCT OF PHOSPHORIC ACID PRODUCTION: Z. Ketone*, D. Yskk, J . Rosenberg, J . Shathue and Y . Volktnan.

A process was developed for the production of phosphoric acid frost rock phosphate by acidulation with HC1. Two alternative Methods of recovering nranium as a by-product of this process were developed.

In the f i r s t method the uranium i s recovered from the undissolved residue remaining after the UC1 acidulation. Ibis residue i s relat ively • l u l l In quantity, unlike that from sulfuric acid acidulation where additional so l ids , i . e . CaSO , are formed. The uranium i s aide to remain in the residue by carrying out the acidulation under reducing conditions, through the addition of iron powder. The concentration of uranium in the residue i s over 0.1Z, as compared with 0.01 - Q.15Z In the original rock phosphate. The uranium i s then acid leached with dilute HC1 and oxidizing agent. A precipitate of 1 - 2X U is obtained by bringing the leach liquor to pUZ. In one more seep a concentrate of 60-70Z U i s obtained by carbonate leach and repreclpitatlon with NaOU. Overall uranium recovery i s 50%.

In the second method the acidulation i s carried out in the ordinary way, i . e . without addition of iron, and thus most of the uranium Is dissolved. Batch measurements of the distribution coefficients of uranium were carried out in order to evaluate the behavior of the uranium la the I.W.I. Clsrael Metallurgical Industries) l iquid-liquid extraction process for preparation and purification of phosphoric acid* . As a result of this study, a novel and convenient method was devised for the recovery of uranium as a by-product of th is process, using solvent extraction techniques.

aeferemce: 1. BAWIL, A. at e l . , Cham. Es*> prog. 58, 11, 100 (1962)

PRODUCTION OF METAL POWDERS 8Y REDUCTION OF METAL SALTS IN SPRAYS*'>: V. Schachter*, E. Foa and M. Konigriwch*

Owing to the very eff icient heat and mass transfer conditions prevailing In sprays, I t Is possible to reduce solutions or ogles of metal salts at relatively low temperatures, at ordinary pressure and at residence times of less than one second. The following reactions were carried out la a glass tube of 5 cm diameter and 1 ra length, heated to about 500*C:

CuSO,, + Hj •» Cu + H.SO. 2 4

F e « 2 + H 2 •» Fe + 2HC1

N i C l 2 + H 2 * Hi + 23C1

CoCl j + Hj -• Co + 2HC1

t C u ( N H 3 ) 4 ] S 0 ' 4 + Hj ->• Cu + U I H 4 ) 2 S 0 4 + 2HH3

Ihe add and other gases evolved can be recovered by scrubbing with suitable liquids» after collecting the metal powder in a cyclone.

The process i s of potential coranercial interest for the working up of leach liquors from metal recovery plants (including Titans) and for the production of metal powders. A significant advantage of the method i s i t s continuous mode of operation, as opposed to the batch-wise operation of other processes. Patents have been Applied for in Israel and eight foreign countries.

Reference; 1. Israel Patent Application No.31231

A LABORATORY APPARATUS FOR STUDYING THE THERMAL DECOMPOSITION OF* SOLUTIONS OF SALTS IN FALLING DROPLETS1**-: E, Foa. J. Bimbeum, Y. Schachttr* and M. Konigsbuch* .

A detailed study of the thermal dissociation of sa l t solutions In s tat ic drops was concluded SOM time ago, using s laboratory apparatus in which the drops ware suspended on platinum loops and heated in a quarts tub* in a s traw of hoc gases* ' . This apparatus permitted the study of the Mechanism of dissociation of s a l t s l a drops as small as 1 X, which la however about one or two orders of Magnitude larger than the droplets in Industrial spray reactors.

• • •Ml tn Untvwiity,

•» Thk work mm wpporttd *" W * *K N B S contract IG) - 1 4 .

- 1 5 4 -

I t e present apparatus was btdlt l a order to obtain data for the Interpretation of the — chenism of thermal dissociat ion of s a l t s in solmtlon i s f a l l ing droplets. Such data ar* of practical Importance for to* Assign of industrial spray reactors. The apparatus consists of a vert ical cyl indrical oven, e l e c t r i c a l l y heated, with an internal diameter of 55 mm, which accommodates a glass or quartz tube 1 st long and 50 am In external diameter. The heating system gives * maximum temperature of 850*C i n the central part of the oven. A lane apparatus capable of producing a flow of uniform drops in the range 50 to 1000 microns diameter i s placed about 30 en above the upper eatraace of the tub* and precisely collimated with i t . An additional collimator 12 em in diameter i s placed between the Lane apparatus and the tube. The droplets produced f a l l freely through the collimator into the oven where they are heated to the required temperature for thermal dissociation. A g lass co l l ec tor i s attached at the lover end of the oven, as well as a tube by which a counter-flow of gas can be introduced from the bottom of the oven. The gas may be iner t , oxidizing,or reducing, and the flow can be accurately controlled with a reducing valve and flowmeter.

To determine the diameter of the fa l l ing drops, they were col lected on a g lass s l i d * covered with a thin layer of hydrophobic surface coating (Dessicotm, Bcckman Co.) placed 20 cm below the dropping nesdle of the

Lane apparatus. l b s drops were counted and measured under the micro­scope. In the 300 to 500 micron range i t wss possible to obtain 50% of the drops with a + 101 deviation from a chosen mean mass diameter. A l e s s accurate but very quick method of measuring the diameter o f the drops consists in using drops of a 20X solution of A1C1, fa l l ing on f i l t a r paper Jsprsenarsd with a l izar ine . rhm drops produce purple c i rc l e s which may be compared with a standard prepared with exactly calibrated drops.

References: 1. 10a, E. e t s i . , J . Sc l . Inetrmm. 44 , 936 (1967) 2 . tf.K. Lane, J. Scl . Inserts . 24, 98 (1947)

PRODUCTION OF PURE METAL OXIDES BY THERMAL DISSOCIATION OF THEIR SALTS IN SPRAYS. PREPARATION OF AljOg STANDARD REFERENCE MATERIAL: E. Foa, Y. Schachter*, M. Konigsbuch* and C. Friedman

Under a contract with the U.S. National Bureau of Standards for the supply of Standard Reference Materials (S.R.M.), the method of

( l 2 ) thermal dissociation of sa l t s in sprays swas applied to the prepa­rat ion of high purity Al-0, in quantities of up to several hundred

Several designs of apparatus were t r i ed , operating both with countercurrent and co-current flow, in order to find a system capable of giving the required yield and purity of product. In the system finally adopted (see f igure) , the reaction vessel consisted of a ve r t i ca l quartz tube 1 m long and 10 cm in diameter, heated in a cyl indrical e l e c t r i c oven. Quarts was chosen 30 as to avoid In t ro ­ducing impurities during the reaction* Ifce spray was produced by a Defensor Model 505 standard a i r humidifier capable of transforming into aerosol up to 800 ml l iquid per hour when working in an open space, i . e . against zero res is tance . The humidifier was attached

Rtoctof temperature control.

Oven temperature control'

T r s / s a J M W w

Fig. l Spray apparatus for thanul dissociation of aalta in aolution

- 156 -

v ia a polyethylene sleeve to die bottom of the quart* tube, for co-current flow operation. At the top the tube was connected to glass cyclones where the product waa co l lected .

Xhe following reaction was used for the production of JUL0.:

2A1C13 + 3H20 > A1 2 0 3 + 6HC1

Alueinom chloride (Fluka analyt ical grade) was dls iolved In water tr ip ly d i s t i l l e d in a quartz apparatus. The working teaperature along the axis of the reaction vesse l »as between 350 and 400*, and at the walls 540"C. with a feed of 200 ttl/h of a 20Z AlCl-'oKjO solution the y i e ld was 4 g A1„0- per hour. The raw aluelaum oxide contained about 5X chlorine or Imam. I t was calcined at800*C Inplatlnua crucibles In order to remove aluminum chloride by eubllsiatlon. Xhe f inal sample contained < 0.061 chlorine, as shown by analysis by the •ercurlmctric methodA*'.

The product waa analyzed speccrogrspMcelly, using several randomly taken saaples to check the homogeneity. A batch of 7 samples before calcination and 22 after calcination was analysed. There were no differences within each batch. The following impurities were found before calcination: S i , 1%, I"e, Cu, Ca» a l l i n concentrations of a few ppm; Mo, Cr, Ag, (< 1 ppm); Zn (* 10 pp»). After calcination the analyses showed s l i gh t ly higher concentrations of some of the elements (Kg, Cu, Ha, Cr, end specia l ly S i ) , while Mi and B- became detectable (< 1 ppm); th i s seems to be due to b i t ter excitat ion of the spectra in the sintered sample, s ince the Al l inee coo became stronger.

Work i s now i n progress on magnesium n i trate .

tsferences; 1. KOMIC8BTC0, K. e t a l . , i n IA-1168 (1968) p.145 2. IDA, E. e t a l . , in IA-112B (1967) p.166, and references therein 3 . KOLTBOrr and STOKE*, Volumetric Analysis, Part IX 334

L

- 157 -

SPECTROSCOPY AND SPECTROCHEM1CAL ANALYSIS

The previously reported new description of Che gadolinium spectra in the photographic infrared resulted in the recent discovery at our laboratory of a long sought system of configurations of Bingly ionized gadolinium. Work on other rare earths is in progress. Energy level calculations of some elements in the iron group have also been made.

Investigations continued on DC arc plasmas by a method previously described. The latter was applied to quantitative spectrochemical analysis of rare earth matrices.

Analysis of trace elements in NBS Standard Reference Materials was continued, as well as various spectro chemical analyses including determinations of minor and trace elements in aaaplea of archaeological interest.

- 159 -

GOOD L-S COUPLING IN SINGLY IONIZED Ni AND Cu11': N. Spector.

While LS coupling dominates the level structure of atoras on the left aide of the Iron group, those on the right Hide can be cost adequately described using j-H or j-j coupling. Seemingly, configura­tions involving the almost closed 3d shell and high excitation energies furnish ideal conditions for these two coupling schemes. It was, therefore, most unusual to detect good LS coupling in singly ionized Ni and Cu, with 8 and 9d electrons and excitation energies well above 100,000 cm . This can happen under a unique condition, namely, for

It a configuration of the type ni n'i where r.'=n+l(and has been kno-.-n for £=2,3, In these configurations the electrostatic exchange parameter Gn(n£,n+12) dominates the energy expression and causes a "Russell -Saundersation" of the coupling scheme.

Test values for the electrostatic and spin-orbit interaction parameters for singly ionized Al and Cu by least-squares fitting of the observed levels were calculated. The results, given in Table 1, clearly demonstrate the unique situation. All level designations enjoy a major component greater than 50%.

TABLE 1 Interaction parameters for Ni II and Cu II. cm

Parameter !li II 3d84d Cu II 3d94d

A 3 C '2 G 4

G 0 G 2 G 4

«d a

rms error

107624 ± 33 1079 ± 3 4184 ± 25

85 I 3

731 ± 29 28 ± 3 1.9± 0.5

677 t 15 30 i 4 99 cm-1

116650 * 13

84 * 2 3.5± 3

721 ± 6 25 ± 3 2.6* 0.5

826 ± 9

41 cnrl

'"he parameter t , has no physical significance.

Reference; 1. SPECTOR, N., Association Europeenne de Spectroscopie Atomique,

Premiere Reunion Annuelle, Paris, CNKS, 1969, Paper No.93

- 160 -

NEW « • f F J * LEVELS OF WNQLV I0NI2EO GADOLINIUM (Qd II): N. {factor.

I* as acteant to locate to* alBalng fundaaeutal configuration 4f 6e of alagly ioolaad gadollniua we reobaerved and Measured th« aadollml«a q K C n a la the wavelength region 730(111 - 12300A. Wa obtalaed a l l a t of 950 gadolinlua l i n e s , 900 of which vara assigned to either Cd I or Cd I I . Ccabinlng tha new observations v l th previous data by Ung.ve found. 11 out of tha 13 l eve l s of tha aubconfiguration * £ 8 ( 7 0 6 « of Gd I I at tha fo l io ' tog poaltlona. In cm" :

% { . - 7992.31 ^ j j . - 9943.78

**#' 9092.48 S^_ - 11343.51

^ - 10292.55 6 r ^ - 12338.25

^ j . - 11034.30 6»2j - 13030.75

^ j . - 11S69.B1 ^•jj. - 13515.16

\ , - 12071.74 -These levels Involve some remarkable features of the Gd II spectrum In the newly observed region.

Reference: 1. SPECToa, !!., J. Opt. Soc. Am. 59, 488 (1969)

"CATHOOE REGION" METHOD FOR THE SPECTROCHEMICAL DETERMINATION OF IMPURITIES IN RARE EARTHS MATRICES: R. Avni, A. Boukobza and A.S. Louranco*

The impurity elements Ag, Al, Aa, B, Be, Ba, Bi, Ca, Cd, Co, Cr, Ca, Cu, Fa, Ga, Ge, Hg, In, K, LI, Hg, Ha, Mo, Ne, Hb, Hi, Fb, Kb, Sb, SI, 5n, Sr, I I , Tl, V and Zn ware analysed in the rare earth matrices CajOj, Dy 2 0 3 , EUJOJ, GdjOj, Ho 2 0 3 , U j O j , Hd 2 0 3 , P r 6 0 u , Sm2°y "0>2°3 * ° d Y 2°3* A M > l T t n * a method deacrlbed previously (1 ) , only tha cathode region, 0.2 am beneath tha upper electrode, uaa exposed on tha photographic plate, instead of the whola arc gap.

Tb* evaporation rata of the matrices, and the axial behaviour of the plaamea (temperature, e l ec tr i c f i e l d , electron density and total particle concentration) ware investigated. Fro* these results and tha spectral l ine intens i t ies of the lapurltiea tha matrices could ba divided

* fnMJftiw af A m u * EfMfar. Sw Paile BratH.

- 161 -Into two groups, namely: a) oxides of La, Sa and Y, and b) the other raw earth tutr ices . The similarity of behaviour within each group allowed the use of standards prepared in only two matrices — Lc 0, and Sd 0 — for impurity deteruinations In a l l the rare earth matrices mentioned. The matrix factors v ' for La2°3 a n d N d 2 ° 3 r j n B e d from 0.8 - 1.5 + 20* .

The detection U n i t s of the impurities were In the range of a feu ppo. A variation coefficient of + 25S was obtained when using the matrix factors. The concentration range of the impurities determined denaitometrically was from 5 to 500 ppm.

References: 1. AVNI, R,, Spectrochim, Acta 23B. 617 (1968). 2. AVNI, R., Spectrochlm. Acta 24B, 133 (1969).

CONCENTRATION AND VELOCITY OF URANIUM PARTICLES IN A DC ARC PLASMA*1*: Z. Goldbart and R. Avnt.

The spatial distribution of uranium flux in a DC arc was oeasured directly by neutron activation of aluminium wires passed through the arc plasma.

To establish the relationship between the number of particles sticking to the wires and those moving in the plasma, wires of different cross sections moving at different velocit ies were used. I t was found that an aluminium wire, or strip, of up to 3.0 mm width, reflects the real flux of the uranium particles when i t crosses Che plasma at a rate between 75 - 300 cm/sec. The mean temperature on the surface of the wire crossing the plasma was measured by coating the wire with sublimating substances (Hg-Cl,, MoOj, e t c ) . The mean surface temparature was found to be 600°C.

The concentration of Che uranium particles in the centre region of the plasma was found to be 10 particles/cm p with an axial velocity of 600 cm/sec.

References: 1. AVNI, R. and GOLDBAKT, Z.,XV Colloquium Spectroscopicum Internationale,

Madrid, 1969.

INDIRECT SPECTROCHEMICAL DETERMINATION OF MINUTE IMPURITIES IN "PURE" AND "HIGH PURITY" METALLIC ZINC: I. SchosnfaU and If.. Ststmr.

NBS standard reference material* Pure Zinc SUM 683 and High Purity Zinc SUM 682 were analyzed for Impurities present in quantities below the sensitivity of direct apectrojraphic measures***a. A tech­nique IM« devised Co concentratt the las«riclM t thereby permitting

-162 -- 2 -3

eecands«eloae 4MM to 10 pea In pare sine and to 10 ppm in high parity time* Tha bulk of th« l ine wee subllaated In vacuum,leaving tarn raaUue —rlrhail la. the lammritiee. Thin technique n i l l a u t l ikely to istroewce contamination Into th« samples.

The system J w l p r t and btcUc for th is wort b u already been described* « Snail chip* of sine were placad on a layer of specpure graphite and heated in vaccmn. the graphite powder with the concen­trated I f i ITTif vae then excltad under suitable conditions. Hotting corves were obtained from synthetic standards prepared frost ZoO with known assents of the impurities.

To* spectroebmmical deteminatlona yielded the following im­parity values.in ppat 0.02 Jfa, 0.20 Sb, 0.40 Hi, 0.06 II In SEH-683, and 0.045 Cn, 0.003 (to, 0.11 Fe and 0.25 Fb In SKH-6S2.

Inference: 1. STEDDm, M., In: IA-U90, p.282 (1969)

SPECTROCHEMICAL DETERMINATION OF SOME TRACE ELEMENTS IN NBS STANDARD REFERENCE MATERIALS: ZINC METAL 6S3 AND ALFALFA: R. Btrcx and S. Held.

Speetrocbemical determinations of Cu, Ag, Fb and Cd In Zinc Hetal SRH 683 were carried out using DC arc excitation of ZnO obtained from the netal by oxidation in an e lectr ic furnace. Sb was used as an Inter­nal standard. The confidence interval of the 95Z probability level in ppst by weight was found to be 6.4-7.1 for Cu, 1.0-1.? for Ag, 9.7-12.6 for Pb and 0.85-1.15 for Cd.

Spectrochsaical determinations of Li and Kb in alfalfa were carried out by DC arc excitation. Dry citrue leaves were used as a matrix for the standards. Cs served as an internal standard* The con-fid>uce Interval of th>i 95% probability level in ppa by weight was found to be 0.8-1.0 for Li and 14.0-16.0 for Rb.

SPECTROCHEMICAL ANALYSIS OF JAR HANDLES FROM ARCHAEOLOGICAL EXCAVATIONS: R. Bkcz and S. HsW.

Jar handles with varying impreisfons and symbols found in dif­ferent parte of the country were analyzed for minor and (race elements. A total of 133 aseples were analyzed. Host of the iample• in the pre­sent work, are similar to the jar handles bearing the "royal" at amp of Jodah formerly investigated by Hlllett et al. ( 1 )

The tochnlene used wes that generally applied in apectrochealcal analysis of slUcatesfvalca Is baaed on DC arc excitation of the sow-

- 163 -derail sample nixed with graphite powder. Some of the geological stand­ard rocks issued by U.S.G.S., C.A.A,S. and C.H.R.S. (Prince) servtd ns standards for construeting the analytical curves. Determinations of Mg, Na, Ti, Hn, Ba, Sr, Zr, V, Cr, Cu, Hi and Co were carried out using photometric meaBurements. The approximate concentrations of K, Li, Hb, Ga, Y, Yb, Sc and Pb were estimated by visual cooparison of the Inten­sities of the analytical lines of the saaples with those of the stand­ards.

Sherds, either found together or believed to have been made In the same locality, were grouped together according to the cedlan T*Auea of each element in each set of apparently similar analyses. The range of concentrations for each group was obtained by taking the lowest and the highest concentrations for each element appearing in the group. This statistical procedure seemed to be the most suitable In this case, where the spread in the concentration values for different samples be­longing to the same group la of interest.

The variations in the concentrations of some minor and trace con­stituents, such as Mn, Ha, K, Mg, Ti, Ba and Zr, might possibly be help­ful in identifying, the origin of pottery fragments.

Reference:

1. MILLETT, A., PR1TCHAKD, J.B. and RALPH, E.K., Archaeometry ]_, & (1964).

GEOCHEMISTRY.

Several mineral and radioactive springs on Che shores of Lake Tiberias and In the Jordan Rift Valley were found to be of probable marine or ig in , f i t t i n g In with what has previously been found fot many other water sources In the Rift Valley. Laboratory expert.aegis shoved that ocean waters In contact with most cocntm rocks change In the direct ion of the present composition of the Rift Valley mineral waters .

The 2 3 V 3 8 U latiosof the Gulfs of Eilat and Suez were found to be 1.18, which i s s imilar to the r a t io la the Red Sea. Age estimations of corals from raised beaches on the Island of Tlran (Gulf of E i l a t ) , as evaluated from the Th/ U r a t i o s , gave reasonable values of 128,000 to 385,000 years .

The volcanic cones and explosion cra ters of the Golan were found to reveal a large number of necks, maars and pyroclastic cones.

The neutron flux produced by cosmic rays on the «urface of the moon was estimated from the flux on the e a r t h ' s surface, taking into account the differences in conditions between the moon and ear th .

» M U / » » U RATIO IN THE RED SEA1'*: F. Yaron and R. Frenkel.

The Red Sea area has scant rainfall and consequently practically no runoff. It is supplied with dissolved chemical compounds by the Indian Ocean only, and one night assume that the Red Sea .and the Indian Ocean should have essentially the same chemical composition and the same isotopic ratios, except for elements taking pare in biological and evaporative processes and isotopes whose half-lives are short compared with the time of mixing of the two water reservoirs.

So far only few determinations of the \5/ U ratio have been (2 3) made to permit testing of the above assumption. We have recently

examined this ratio at the far northern end of the Red Sea. The first determination was made on a coral taken from the Gulf of Eilat, about 20 km south of Eilat. The age of the coral determined by the

Th/ U method was about'4000 years; Its 2 3 4 U / 2 U ratio vas 1.18+0.026 The second determination uas made on a coral taken near t'as es Sudr, about 60 kn south of Sv a.. The age of this coral was about 600 years and its U/ U ratio 1.1S+0.030. A water sample taken froa the Gulf of Eilat about 6 km south of Eilat had a V/ V ratio of 1.19±0.021.

These r e su l t s compare with the values of 1.14-1.16 for the Indian Ocean ( 2 ) and 1 . 1 8 ( 2 ) and 1 . 1 5 ( 3 ) for the Red Sea.

References: 1, YARON, F . , and Frenkel, R., I s rae l J . of Earth Scl . (in press) 2, KOTDE, H. and GOLDBERG, E.D., in Progress in Oceanography Vol. 3,Ed.

M. Sear,Perganion Press , 1965, p.173 3, VEEH, U.H., 1968, Geochim. Cosmochlm, Acta, 32, 117 (1966)

ABSOLUTE DATING OF SOME MARINE TERRACES ON THE ISLAND OF TIRAN<!>: F. Yaron and M. Goldberg'

The Island of Tiran is si tuated a t the northern end of Che Red Sea at the entrance to the Gulf of E i l a t , I t i s located near the Intersection of the NNW trending Red Sea Rift with the N-S trending Dead Sea - Ei la t Rift . Raised marine terraces a re a prominent feature of the island, mainly along the south-western slopes. These terraces extend froo 2 m up to approximately 500 m above recent sea level and are believed to have formed during quiescent stages of the tectonic history of the uplifted i s l a n d * 1 , 2 ) . This uplift ing began in the Pliocene! or even ea r l i e r , and continued up to the recent epoch. B a l l ^ 3 \ who described similar raised terraces along the Re»

* Gtoloslcal Sutvty, Mlnlttry of Dcvtlopmtnt

- 168-

S M coasts, attributed those above 100 m to the Miocene and Pliocene •ad those below 100 • to tb« Pleistocene and younger.

An attempt v u mad* to data some of tht raised marine terraces by the 2 3 0 I h / 2 3 4 U method. Three Maple* vera chosen: G-l, consisting of corals, Flatygyra sp. and Plesiastrea »p.; G-2, consisting of bio-clastic calcarenitt taken Ire* a young terrace some 2-8 m above sec level; and G-3, consisting of corals Pavia taken from an old terrace about 450 m above sea level. The ages of the samples were calculated fro* the T h / ^ I ratio as described by Kaufman and Broacker^. The ages found vere 123,000, 217,000 and 385,000 years respectively. The last-mentioned figure is however very uncertain, being outside the limits of sensitivity of the present method.

The vf v ratios were also determined, is saaple G-3 the rather high value of 1,2240.01 va* found. If the coral may be consi­dered a closed system, which leems to be the case, then extrapolation to xero age gives a ratio of nearly 1.32. Assuming that no Isotonic discrimination occurs during Incorporation of the uranium by the coral, this would indicate a very high 2 M t r / a 8 0 ratio in the sea at the time the coral was formed. If this high value is corroborated It would still remain to be found whether it was the result of special condi­tions in the area or whether higher ratios were generally characteris­tic of the ocean 139,000 years ago.

References? 1 . GOLDBERG, H . , The Geology o£ the I s l a n d of T l r a n . G e o l o g i c a l

Survey of Israel, Ministry of Development, 1957 ( i n Hebrew) 2. GOLDBERG, H., Iirael J. Earth-Sel. 12, 2 (1963) 3 . BALI, J . , Contribution to the Geology of Egypt, Survey of Egypt,

Cairo, 1938 4. KAOTHAN, A. and BwOECKSR, '.J., J. Geophys. Res. .70, 16, 4039 (1965)

COMFOtmOHAL CHANGES IN SEA WATER IN CONTACT WITH ROCKS<>>: E. Mexor.

Sea water coming in contact with common rocks undergoes conposi-

tlonal changes, e .g . loss of Na, gain of Ca, Sr, Li, Br and occasionally

£a,«sd either loss or gain of Hg, K to. i0.* This trend, long known

for ornate waters, has been obierved in landwards infi ltrating sea

water In our eeastal plain, and i s suggested to account for the present

composition of the Tiberias-Molt mineral waters in the Rift Valley.

The procasf has been simulated in a series o£ laboratory experi­

ments In which powdered rock was stirred with wan sea water. The

results are summarised in the figure.

240

220

200

•o

0 3

4

l»

2 4 0 " 180 "•

6 0 0 • . 3 " 2 0 0 -* t o 5 6 0 - 14 -' r * - 02 -' r *

160 160 "•

140

520 I 12 , 1 4 ^ — o c e a n

2

120 ° " f 4 8 0 • ^ ° 10

„ 120 =—•" ocean • ° • 1 - o 0.1 - o

eo • t . 1

4 4 0 ° S - 1 ^ — ^ o c e o n • t . 1

100 - r # 8 4 0

• t . 1 • 4 0 0 - 6 - 8

n ^ • K " 8 o " 2 1 » 8

ocean ^ ^ ' ' o ' c e a i r Mg

Fig. 1 Changes in the composition of sea water stirred with common rocfe powders (open circles), compared with sea water (bars). The compositional deviations achieved are in the direction of the composition of averaged representatives of natural Rift Valley waters (solid circles). This is true for Ca, Mg, Na, K, S T , and Li. The Br data seem to be analytically doubtful and will be further checked.

1. MAZOR, Feb. 1969,

£ . , Froc. Annual Meeting of the Israel Geol. S o c , P-4

THE HAMMAT GADER, NUQEIB AND GOFRA SPRINGS^0 E. Mazor end M. Moco.

The hydrochenistry of the Hasnat Gader hot springs (29-51'C) south-east of Lake Tiberias, and of the two sulfur strings Nuqeib and Gofra north of Bin Gov, w « Investigated. At HseMat Gader four springs represent mixing of cold salt-poor water with hot vLncrtllxed water. This i s Indicated by the cheaicel composition and the ttaperaturts. The Nuqeib and Gofra springs have a similar coaposl-tion (see Fig. 1) . An origin from trapped oceanic waters i s proposed.

1 0 0 0

1 1— 1 • 1

A, 1

-Hi l l

1— 1 —l • i — •

100 /it ^^

. ^ w i i

IP

J >.

' J&y "—^

IP

J 10

1

G- C*fn * * r i t * MfuHfppw- HoKch iprtng H l H o w w Match tptinQ

t i I r '

M M ' /

1 < i • Li*K>0 Sr K No U 3 Ca 1,100 Br CI S 0 4 HCO,

fig. 1 Coapesitional s imi lar i t i e s of the Nuqeib, Gofra and Malich mineral springs.

Reference: 1. HAZQRy E. and MLCHO, M., leva Va'anta i l , 5, 260 (1969)

PYROCLASTJC CONES AND EXPLOSION CRATERS IN THE GOLANM: E. Mazor. A prelininary survey of the explosion volcanoes and craters of

the northern Golan has been carried out. These include over 70 pytoclMwtic cones, •any with wel l preserved craters (one of then hosting Lake R n ) , as v e i l as over 20 aaazs (secondary, or phreatic explosion craters) , and several beautiful oiniature s ingle and double necks. See F i g . l .

- 171 -

* Volcanic cone * Cone wilti one OF more criters o Moor (crater with low or no rampart) A Explosion neck = Israel-Syria cease fire line

Fig. 1 Pyroclastic cones and explosion craters in the Golan

Reference: 1. MAZOR, E . , PTDC. Meeting of the I s r a e l Geol, S o c , Oct. 1969,

p.26

NEUTRON FLUX ESTIMATES ON THE MOON: J. Kastner,* B.G. Oltman,* Y. Faige

and R. Gotrf.*

Heutron fluxes generated by comic rays in lunar material were recently deduced from our knowledge of neutron production by comic rays in the earth's atmosphere and at the air-ground interface • It was assumed that the total neutron flux at the moon's surface will be enhanced because of the lack of a shielding atmosphere and the absence of a lunar deflecting magnetic field. The higher average atomic •ass of lunar materials will also result in a greater ylald of neutrons by comic rays and lower slowing down* so that more of the neutrons can leak out Into space. The thermal neutron flux will be further enhanced

- 172 -

nana aril with the terrestrial air-ground interface bacauae of the lade ef altreoca welch acta as a elak In oar itno.pher* (for the induction ef C). Moceoveg, the aooa'a gravity will Crap moat thenaal neutrona, aapartally oa tha night alia, where the aooo/'e eaespa velocity of 2.4 ka/aec la certalaly greater than tha maan apeed of tberaal naenrono. allealeg for tba above •eatloaad factor*, tha aautlon flaxee at tba

2 aaae'a aarfaea were eetiaated aa 500 - 1000 n/ca /aln for faat neutrona (between 1 - 1 0 HeY) and 1000 - 2000 o/ca2/*dn fox tbaraal neutrons,

5 2 baaed oa average value* of 350 faat n/cm /day and 310 tbsrael n/oa /day aaaaarat la argoeaa, 111., (42", 85W). Ikeee aztrapolatad lour flux** are probably aeoat oaa ordar of aagoltud* too high. If tha flux at tha aooa'a anrface la coeeiderably lower than ooc half of the niidaua value to ee expected within taa lunar cmat (aoon-vacuua interface)( ',

la' tba above calculation*, fcowever, eh* production of neutron* ana to the interaction* of charged piona at tba lunar Croat vaa not cakaa into acconnt. Huch of Che energy of a priamry coaaic ray proton goaa into the creation of piona • (and aoaa heavier elementary partlclee) whan tba proton atrlfcaa a target nucleue (0, Si, etc.) end break* it up* . the charged piona, which generally decay (half-life « 2.55 x 10" aac) in tha terreatrial ataoaphere before Interacting with ~aa atoa froa the air, will produce nuclear caacadee on the lunar i enrface rather than decay la flight, and thue add eignificantly '(aaoat a factor of two) to tha neutron coaponeate on tha lunar surface However, the extranely; abort-lived neutral v° aaaone (2 x 10 aac) proeoced in the* noon* a cmat will practically all decay there before they have a chance to Interact with lunar •atarial. lafareac**: 1. IsgTKU, J . , OLTMalt, B.C., IUGE, T. and GOLD, I . , Health Phya.,

Jtf. '12 (1969) 2. Taaacra, i.i., annas, e.e. wot Bess, U.K., J. Saopnya.

gaa. «£, 2M5 (1561) 3 . MUSI, » . , Coaaic Say*, McCrew Hill look Co., H.I., p. 172-176,

19«*

- 173 -

FOOD IRRADIATION AND APPLICATIONS OF TRACER TECHNIQUES.

The food i r rad ia t ion program during 1969 concent raced era inly on two aspects, Che i r rad ia t ion of several hundred tons of potatoes and onions for large-scale storage and public coasuner t e s t s , and the treatment of several tons of c i t rus f rui ts with various combinations of i r rad ia t ion , pre-heating and waxing to prolong storage l i f e and to determine conditions that prevent development of peel dasage l a the .stored f ru i t - The potato i r radiat ionsv ;re carried out with t i e Xuaec portable i r rad ia to r {used in the Pillsbury potato t e s t in t i e 0.5.A.), which was rented for 7 months and se t up a t a regional potato sort ing house in the south of I s r ae l . The program was sponsored jo in t ly by the Is rae l Ministries of Agriculture and of Commerce, the I s rae l Atomic Energy Commission, the Vegetable Marketing Board and the Sliaar Hanegev Regional Council. Other investigations included s t e r i l i z a t i o n of bread (in cooperation with the Is rae l Defence Army), and a search for new types of bread res i s tan t to s ta l ing for a feu weeks, vitbout i r r ad ia t ion . Experiments on different kinds of i r radia ted animal feeds were carried out in collaboration with the Animal House Department of the Badassah Medical School, Jerusalem, and with a large-scale commercial producer of animal feeds.

In the tracer techniques program, water pollution and vent i la t ion studies were continued, and the flow dyamics in a large reservoir of the National Water Carrier was measured.

ATTEMPTS TO REDUCE POSTIRRADIATION OAMAGE TO THE PEEL OF STORED, FIELD INFECTED CITRUS FRUIT: R. Barkai-Golan* and R. Padova.

A series of experiments on oranges and grapefruit was carried out during the 1968-9 harvest season,as part of the continuing effort to reduce radiation damage to the peel and to control fungal decay of export-grade citrus fruit . Fruit was drawn frera various processia? stages of a commercial packing house , and the effects-of the following were tested: a) doses of 10-50 krads on fruit waxed by commercial spraying,as compared with fruit dipped £ n "Zivdar" wax emulsions; b) doses of 10-50 krads following dipping in water at temperatures between 45° and 52°C for 3 or 5 nin; c) effect of the :i=e interval between heating and irradiation on the efficacy of the syner­gistic action betueen radiation and heat.

Both types of waxing had the sane effect on peel danage of Shamouti oranges, but in some expericents repeating the dio gave better protection than a single dip. The radiosensitivity of Shamouti varies during the harvest seasor. Early in the season (late November and December) the incidence of below-export grade fruit was very high, especially in degreened fruit (70-8031 rejects vs. 25-50% for non-degreened fruit). The incidence of rejects was similar in January (27-49%) but fell to a very low level (3-5*4) towards the end of Che season (late February and March). A combination of heating (50° or 52"C for 5 minutes) and radiation (35 or 50 krads) reduced the incidence of rot to 0-0.5X. The untreated controls had up to 10?. ratted fruit at the end of the storage period (6 weeks). Irradiation alone did not control rot, which also occasionally reached 102 after 50 kxad treatments.

For grapefruit, combined treatments (35 or 50 krads following 5 minutes at 52 BC) showed less damage (3-12X) than Shamouti oranges. The method of waxing did not affect these results. For a given radiation dose, heating reduced the incidence of damage compared uith radiation alone. Hot Incidence was low in control grapefruit (1-22). Radiation alone or a combined treatment reduced this to OX.

Valencia oranges were treated with relatively low radiation doses (10-20 krads) which sometimes caused a high incidence of rejects (1-20%). Heating before radiation reduced the rejects by 502. Conblned treatnents reduced the Incidence of rot to 0-1%,while for irradiation alone the incidence of rot was, like for Shaaouti, much higher, reaching 122 after 1 month of storage.

• Volc*i! Inn of Aplcultural Rtttweh.

- 176 -

Jifmra 1 . BaKAI-GOIJul, * . KAHAK, U . S . and PADOVA, K. i n I A - U 9 0 , 224 (1969)

COMBINED HEAT. RADIATION AND DlPHENYL TREATMENTS TO REDUCE ROT IN CITRUS FRUIT INOCULATED WITH KNfCILLHMt ITALfCUM AND PENICILUUM D1G1TATUM: R. oarfcai-Golsn*, R.S. Kahan m l R. r*adow.

In on* act of experiments the effect of combining Irradiation and heat treatments to increase eh* radloaensitiYity of PenlcllUuai i ta l l can , the caueal agent of blue rot In cltrue frui t , was studied, in sa attempt to obtain better control of this fruit storage disease. Tae ia> vivo development of the fungus uas investigated in three kinds of citrus frui t - grapefruit,and Shanouti and Valencia oranges. The fro i t was inoculated vith a 10 /ml spore suspension of a singla-»pore culture of P. i ta l i cua , after which i t was heated to SO* or 52*C and then irradiated with 35 or 50 krads of Co gawse rsys .

The cosbined treatments aarkedly prolonged the storage l i f e of the frui t , compared with frui t which received only heat or irradiation. In oranges, a coabinatlon of 52*C and 50 krads prolonged the incubation period, i . e . the time unt i l the f i r s t frui t rotted, to 10-11- days, vs 7-8 for oranges receiving either s ingle treatment. After 25 days storage a t 14"C» the incidence of rot for combined treatments was 15-171 vs 70-80* and 85*100% foe heat or irradiation treated fru i t , respective­l y . Combined treatment was sec t effective for grapefruit where the n o n u l incubation period i s several days longer than in oranges, even i n untreated f r u i t s . The Incubation period was 17 days for the coabined treatment, aad after 35 days rot incidence was only 3Z vs 50-90Z for fruit receiving a s ingle treatment.

In a coabined treatment, reducing the dose shortened the incubation period less -than did lowering the temperature. Coabined treataent was l e s s effective for Shaaouti oranges inoculated with P. i te l lcua than for those inoculated with 7. dlgitatua, where only SX rot occurred after 50 days. The reverse was true for grapefruit, wfp-.re coablned treatments were acre effect ive againat T. Italicua* ' .

In another series of experlaonts a coabinatlon of heat, irradia­tion aad dlphoayl treatments was tasted for the control of rot in Valencia oraagas Inoowlated v i ta spores of Penicilium digltatum. The treatment extended the storage l i f e of the fruit for a longer period than when east* of the treatments alone or coabinatlona of any two . of taea wen applied. Vie laeabatlon period of the fungus la fruit stored at 14*C was extended fee- 14 days vs S-10 days la frui t

* Vakanl tnttltuM tar Afrfailwral Wimrrti,

receiving contoliied double treatncnta, 8 days in diphcnyl treated fruit and 6 <i*jrs la untreated fruit or In fruit that uaj c icior caly irradiated or heated. A reduction in the irradiation dose or in the heating time did not shorten the incubation period of tne fungus, but resulted la an increase in the percentage of decayed fruit at i-.e end of the storage period.

Irradiation and heat, without diphenyl, was found to be sore effective than any of the other double treatments and nearly as effective as the combined triple treaczeat of heat-lrxadiatlon-diphenyl. Combination of Irradiation or heat with diphenyl clearly enhanced the effect of each treatment by i t se l f t extending the incubation period of the fungus.

Reference: 1 . 3ARKAI-GOLAN, R . , KAOA.V, R .S . and PADOVA, B. , Phy topa tho logy 5±,

922 (1969)

EFFECTS OF GAMMA RADIATION ON ETHYLENE PRODUCTION. PHENYLALANINE AMMONIA-LYASE ACTIVITY AND PROTEIM SYNTHESIS IN GRAPEFRUIT PEEL*: J. Riov", S.P. MoroeUse", R. Goran" and R.S. Kalian

Irradiation of grapefruit with 200 larads gansa rays enhanced ethylene production,which attained a peak 12 hours after treatment. Subsequently ethylene production rapidly decreased eitlier to control values (fruit at early maturity), or to about 50 per cent of naxi=u= (fruit fully ripe) . Phenylalanine aasnania-lyase (PAL) act ivity curves followed the same pattern, but with a certain tine lag. Early fruit shoved no dinage; pitting of the peel occurred in fully ripe fruit .

Dose-effect studies on fully ripe fruit} 22 and 120 hours after irradiation, showed that effects of relatively low doses (25-100 krads) resembled the affects of 200 ktads on early fruit (a decrease of ethylene and PAL to control level* end no danagc). At 400 fcreds etnylene production and PAL activity increased, resulting in severe peel damage.

The data, obtained suggest that ethylene induces PAL activity in irradiated frui t , perhaps through da novo protein synthesis. Effects of gaesu radiation on protein synthesis ware, therefore, studied by incorporating C-laucine into newly synthesized protein. A linear relationship was found between the increase in irradiation dose end the inhibition of protein symthesi*. Four hundred krads elswet completely

* Joint H w i t h PraJMt wHh iht IAEA m Hs*r t« t 0«Mg> W Chrw P«>Hw* I * IMMtan S» Om*m in E W Y I M ActMly •nd tn P M I Conntawnta.

* • PKUXV of AfricuHura. HAnw Untonfty. (Wtawot.

-178 -

inaioited protein synthesis, MO recovery fro* the inhibitory «ff«ct of

a relatively low (100 brads) dose on protein synthesis was detected,

Van ppa ethylene did not affect protein synthesis, while 103 ppm

inhibited i t by 502. Tht increase in I'AL activity through ethylene

production nijht therefore be due to the synthesis of specific proteins

whfcti are not affected by the general inhibition of protein synthesis.

DEVELOPMENT OF DISCOLORATION OF THE SPROUT BUD DURING POSTIRRADIATION STORAGE OF ONIONS: N. Tecnkm-Gcfooetski*. R. Padova and R 5 . Kahan.

Experiments were carried out on the 1968-1969 crop of Grano,

Egyptian and Hiverside variety onions, as pert of the continuing (1 2)

effort * to establish the causes of sprout darkening and to find methods of preventing or diminishing it. Onion bulbs of the 3 varieties were irradiated at 8 different doses in the 1-80 krad range. Egyptian and Riverside varieties uere treated either immediately after harvest or one Month later; Grano vas irradiated only one month after harvest. After irradiation the onions were stored either at ambient teoperatures in open sheds, or in refrigerators at 0*C. Periodically, onions were cut open and the inner sprout scored for growth and/or darkening on a 0-4 scale.

Doses of 1 krad did not inhibit sprouting and caused no darkening at either storage temperature.

For Grano onions harvested in July, no damage at all appeared during storage at 0*C,and until March no damage appeared during post-refrigerator shelf life. Onions treated with 2-20 krads and removed frost refrigeration in fiarch developed degree 1 daaage during shelf life, while those removed in later Months developed up to degree 2 daaage. For onions stored in open shads, there was a relation between the degree of darkening and the length of storage. Ho darkening appeared during the first 4 Months, later darkening of degrees 2-3 was found In son* of the onions.

No damage was observed,for either irradiation date,for Egyptian onions harvested in July and stored at 0*. Negligible daaage developed during 1 Month of shelf life subsequent to 7 souths of refrigerated storage. At aabient temperature, daaagc began to apptar only 3 months after harvest, and was independent of the date of Irradiation. After 5-6 months, there was moderate darkening (degree 2-3) of the sprout bud. The darkemlag vas independent of dose in the range 2-20 krads, but waa mora eroaeaneii after 40 and to krads.

* Votami trm. nt Aft*Aturrt MMKh.'

- 179 -

Riverside onions stored at 0° gave results alnilar to the other varieties and very slight darkening began to appear only one c»nch after removal from refrigeration. For open shed storage, very 3llghc darkening began to appear after 2 raonths and did not beccce =ore intense until 4 months after harvest. No further darkening occurred during up to 7 months postharvest storage. The date of Irradiation did HOC affect the degree of darkening.

There was in general far less darkening in the 196B/69 crop than in previous years. Further experiments on the 1969y70 crop are in progress to verify the effect? of the size of the dose and of the interval between harvest and irradiation, which seeced to influence Che intensity of darkening in our earlier investigations

References: 1. KAHAN, R.S., TEHKIN-GOHODEISIU, II. and PADOVA, R., IA-116S. 149

(1968) 2. KAHAN, R.S., TEXKIN-GORODEISKI, S. and PADOVA, R., in IA-1190,

22 (1969)

STORAGE EXPERIMENTS O N IRRADIATED ONIONS: R. Podova. 1. Ross and R.S. Kahan.

About 40 tons of onions, including 27 tons of Egyptian (pungent) variety, 8 tons of Riverside (sweet) and 5 tons of Grano, were irradiated with an average dose of 7 krads during the summer of 1968. Grano is an early maturing variety which is expected to become an important export item if sub-export quality bulbs can be scored and used for consumption in Israel.

The onions were stored in open sheds in the following 4 clinatic regions,to test the effects of temperature and humidity on storage quality (incidence of rot and loss of weight): a) a very damp region near the sea (Nahal Soreq); b) a moderately hunid region (Sde David); c) a dry region (Gilat); d) a very dry region (near Beersheva).

Grano onions, which were stared only in regions (c) and (d), remained in good condition and saleable until early November (about 6 months post-harvest). The skins then started to shrivel and incidence of rot increased to 10% in both irradiated and control onions. 0£ the latter » 25% had sprouted vs. OX for onions which received 7 krads.

Tli* results for Riverside ware different froa the 1967 crop and did not show higher rot incidence in the humid regions . Rot was in the 2-8X range and the lower values were not always for onions

180 -

scored in the dr ie r region*. Sprouting was OX vs . k$7, for control*. Loia of ticit'nt was 13Z at Sde David and somewhat higher (16X) in the d r i e r region* (c> and £4).

Xgyp&ias variety onion* frost a l l 4 storage regions were 1001 saleable at the end of February vs . only 45-652 for controls. Especially noteworthy was the hatch stored in hwnid region (a),which remained saleable u n t i l »id-A?ril (sore than 9 months a f te r harvest) , l ae loss of weight was much lower In the humid regions, being 10.d% in region (c) vs . 16,7% in region (d).

CHEMICAL ANALYSES OF STORED, IRRADIATED ONIONS: M. Molco and R.Padov3.

In order to investigate what happens during the storage of onions t

a ser ies of cheadcal analyses were made on three onion var ie t ies -Grano, Egyptian and Riverside. Onions i r radiated at 7 krads and non-irradiated controls were stored a t aabient temperature. Vitamin C content, reducing sugar, t o t a l sugars, t o t a l soluble solids and dry na t te r were detersined one day a f t e r i r rad ia t ion (except for Grano) and nonthly thereafter for 5 nonths.

ttoring the storage period there was no noticeable change in the vitamin C content, and no difference was observed between the i rradiated and non-irradiated onions. Similar r e su l t s were obtained for reducing sugar except that there was a decrease in sugar content toward tile end o£ the storage period in a l l onion va r ie t i e s .

An increase of 2 to 2.5Z t o t a l sugars was observed In Egyptian and riverside onions immediately af ter I r radia t ion. The sugar content remained high during 5 months of storage unt i l January, when there was a aatlced decrease for i rradiated aad nan-irradiated onions of a l l 3 var ie t ies .

1'otal soluble sol ids were almost the same for irradiated and non-irradiated onions during the f i r s t three months of Btotage^hen there was an increase of 0.5 - 1.5% in i rradiated Riverside and Egyptian onion*. At the end of January very similar percentages of T5S in i rradiated and non-irradiated samples were observed.

A higher oerc*ntage of dry matter in Egyptian onions was observed iaaadiately af ter i r rad ia t ion , but the i n i t i a l and f inal content for both i r radia ted and non-irradiated onions was about th t sawe. SiMilar- resul t s were obtained for Riverside and Grano va r i e t i e s , only the: oercant of dry matter «ao l a t a .

EFFECT OF IRRADIATION ON CHEMICAL COMPOSITION OF STORED POTATOES: E. Eisenberg, M. Molco and R. Padova.

Ihe amounts of various constituents such as vitanln C, reducing sugar, to ta l sugars e t c . are important factors determining :^c quailty of stored potatoes. Experiments were carried out to establish t ic effect on these constituents of Irradiat ion used to preserve t.ie potatoes, as coinpared with the effect of preservation by cold storage-

One experiment was conducted vith the t'p-to-Datc variety o? potatoes, which is the main variety gram in I s rae l . The irradiated potatoes received a dose of 10 krads and were stored at W'C, and the controls uere kept in cold storage at 4*C. Figure 1 gives the analyses of the various constituents over a period of 4 months after harvesting. Tne

First week Third <attk

^ ^ I I ' I I I I 1

U l t t t t X I " D ffl tt Tin* (months)

Fig. 1 Content of various constituents of i rradiated potatoes, stored a t 16*C,

compared with non-irradiated controls stored a t 4"C

\ l I I I I I I I I I I I I

1 I I I < I • I I I I I UP lo dote voritlyiguoora

_L_ _L_ ' t i _

I i I I I I I I I I

•fljpho vor)>ly:SuOgrj

.80 100 120 140 20 Day* aflir picking

Fig. 2

100 120 140

Content of various constituents in stored irradiated and non-Irradiated Up-to-Date and Alpha potatoes

result! for two batches of irradiated potatoes are shown - one irradia­ted during die f i r s t week after harvesting and the other during the third weak. Stat ist ical analysis by the range aathod^ ' gave good agrteaent with the plotted results . I t can be seen that in the irradiated potatoes,sugars and total soluble solids decreased over the i n i t i a l values (a favourable trend), while in unirradiated samples they increased by 1-3Z during the 4-iumth test period. Vitamin G was higher in irradiated than in non-irradiated potatoes. The effect of radiation on starch and dry natter was found to be negligible.

In * second set of experiment* the effects of the Irradiation on two different varieties of potatoes - Up-to-Date and Alpha - were compared. Irradiation was carried out one day after harvesting. The results are plotted in Fig. 2. The reducing and total sugars in the irradiated potatoes of both varieties were much lover than in the cold storage controls, except on the second day after irradiation whan the content was higher. This phenomenon has already been observed by other investigators (2,3)

- 183 -

The v i t a m i n C concen t of I r r a d i a t e d p o t a t o e s was h i g h e r than c h a t of

t h e c o n t r o l s , e x c e p t two days a f t e r i r r a d i a t i o n . Alpha p o t a t o e s ,

I r r a d i a t e d and n o n i r r a d i a t e d , were lower i n v i t a m i n C and In l e d u c l n g

ami t o t a l s u g a r c o n t e n t t h a n Up- to -Da te p o t a t o e s , i m m e d i a t e l y a f t e r

p i c k i n g and after up to one month o£ storage.

R e f e r e n c e s :

1 . GAZITII, M., A n a l y s i s of v a r i a n c e by t h e r ange method, t i l l s r e p o r t . 2 . PEDERSEN, S . , Food Techno l . 10 , 532 (1956) 3 . SCUREIBER, J . S . , Food R e s . 2 3 , 464 (1958)

STORAGE TEST OF WINTER HARVESTED POTATO CROP: R. Parfova and V. Ross.

Four t o n s of Up- to -Da te v a r i e t y p o t a t o e s s o r t e d commerc i a l l y a t

t h e Shaar Hanegev g r a d i n g s t a t i o n i n Feb rua ry 1969 were i r r a d i a t e d

e i t h e r immedia te ly a f t e r h a r v e s t i n g and g r a d i n g o r a f t e r " c u r i n g " f o r

2 weeks a t 14"C. Four g r a d e s were t r e a t e d v i z . g r a d e A s t o r a g e q u a l i t y ,

g r a d e A immedia te s a l e , s m a l l p o t a t o e s (50-SOg) , and washed s m a l l

p o t a t o e s . The f i r s t 2 g r a d e s r e c e i v e d a v e r a g e d o s e s of 10 k r a d s and

t h e s m a l l p o t a t o e s e i t h e r 6 o r 10 k r a d s . S t o r a g e was a t ambient

t e m p e r a t u r e s I n sheds» e x c e p t f o r a s m a l l q u a n t i t y h e l d a t 1 4 B C . Sacks

were p e r i o d i c a l l y wi thdrawn f o r t e s t o v e r a p e r i o d o f 4 mon ths .

Open s t o r a g e was s a t i s f a c t o r y u n t i l mid-May, w i t h l e s s t h a n 2J r o t

f o r most t r e a t m e n t s . S p r o u t i n g was c o m p l e t e l y i n h i b i t e d by 10 k r a d s ,

w h i l e 15% - 202 s p r o u t i n g o c c u r r e d a f t e r 6 k r a d s , v s . 1002 s p r o u t s ,

up t o 7 cms l o n g , i n c o n t r o l s . The i n c i d e n c e of r o t (ma in ly s o f t r o t )

t h e n i n c r e a s e d r a p i d l y and reached 20-402 by t h e end of J u n e .

There was n o t more t h a n 5% r o t by t h e end o f June I n p o t a t o e s

s t o r e d a t 14*C. The 6 k r a d t r e a t m e n t d id n o t c o m p l e t e l y i n h i b i t

s p r o u t i n g , b u t t h e s p r o u t s formed were s m a l l and r e a d i l y f e l l o f f .

The 2-week c u r i n g p e r i o d b e f o r e i r r a d i a t i o n d i d n o t r e d u c e r o t

i n c i d e n c e .

RETARDATION OF THE POST-HARVEST RIPENING OF AVOCADO PEARS: G. Zaubtrmin*, E. Eisenbtrg, R.S. Kahan and M. Nadal-Shifmann*

Exper imen t s on d e l a y i n g t h e r i p e n i n g of avocado p e a r * by g u m CI 2)

i r r a d i a t i o n ^ * were c o n t i n u e d on t h e E t h l n g e r v a r i e t y , which a p p e a r s

t o b e t h e nose p romia lng o n e . The f o l l o w i n g p a r a m e t e r s were c h e c k e d :

a ) d e l a y i n i r r a d i a t i o n of 1 and 2 days a f t e r p i c k i n g ; b) i n f l u e n c e

of t h e r e g i o n where t h e avocado was grown; c ) e f f e c t of p a c k a g i n g i n

s e n i d o a e d p o l y e t h y l e n e b a g s .

P rev ious , r e s u l t s on de l ayed r i p e n i n g b y 5 *nd 10 k r a d * i r r a d i a t i o n

* Voltanl Innitutt for Agricultural *M»*ch.

- 184 -

vera confirmed. Waxed fruit* Irradiated at 10 kradi 2 days afttr plcklcg and atorad ac 14"C for 15 daya shoved dt«p ihrlnksge at tha atas end of the fruit . The same damage appeared in the prevloui year la irult irradiated 3-5 daya after picking, t t seena that fruit must be irradiated not later than one day after picking.

Both non-lrradlated avocado and avocado irradiated at 5 and 10 krads from itoah Banlkra became mature 2 days earlier than similarly treated fruit from Kvutzat Shil ler. Damage at the stem end of fruit Irradiated 2 days after picking was greater in fruit from Rosh Hanikra. Packing irradiated fruit in semlclosed polyethylene hags bad an effect almilar to that of vaxlng* in that i t prevented the appearance of dark spots caused by drying out. Waxing delayed ripening more than packaging in polyethylene. After 21 days, about 50-70Z of the waxed fruit irradiated at 5 and 10 krads was s t i l l hard, while similarly irradiated fruit packed In polyethylene was 100X mature and soft .

Kcferencea: 1 . ZA0BEKHAJW, C , EZSEMBERG, E . , EaHAff, R . S . and HADEL-SHOTttHH, M.,

i n I A - U 6 S . p . 152 (1961}) 2 . ZAOBEKKAini, G . , EISEHBERG, Z., «MUH, R . S . and HADEL-SHIFMANN, M. f

in IA.-1190, p.226 (1969)

PROLONGING THE SHELF LIFE OF BREAD: E. Ebenberg and G. Arw*

Aa part of a larger project on preserving bread by ionizing radiation, experiments were carried out in commercial bakeries to examine the possibil ity of prolonging the shelf l i f e of bread by varying tha combination of flours, cauls i f iers , hygroscopic materials, o i l s and sugars.

Tha following materials were checked: flours - whole, white, rye and potato flour; hygroscopic materials - glycerine and corn syrup; emulsificr - glyceryl nono-stearate. Many different combinations and varying amount* of theae ingradiante vera tasted.

The bread was sl iced and packed in polyethylene. Organoleptic properties, appearance of mold,and water content ware tasted for up to 7 days itorag** I t was found that the ahelf l i f e of bread i s improved by addition of H glyceryl mono-stcarata plus 2% o i l . A further improve­ment caa be achieved by adding 0.751 glycerine or kX corn syrup. A combination of 452 whole flour, 252 white flour and 30Z rye flour was found to be bast. Addition of 0.31 calcium propionate as praservativa aearned to be an adequate level for preserving bread up to 6 daya.

Additional experiments are required to check more parameters.

DFTERMINAT10N OF THE DILUTION OF A GAS DISCHARGED IN A SPECIALLY VENTILATED ATMOSPHERE: Ch. Gilalh and S. Lak.

If a polluting gas is discharged at flow rate q Into a rooo possessing * classical ventilation systea with air renewal at « flov rate Q. then the dilution factor F of the gas is given by 7^- If the gas contains the pollutant at a concentration C , then the concentration in the rooo at steady state, C, Is given by — - jjj— Under special conditions, e.g. with the ventilation systea ° sucking free the vicinity of the discharge source, the efficiency of the ventilation may be greatly increased.

A method was developed for measuring the dilution factor for any given conditions of ventilation. The nethod is based oa injecting a pulse (activity A) of radioactive gas (e.g. Kr) into the flow of gas (flow rate q) and counting the activity at any desired point with a detector having a sensitivity S , If N is the total net count registered, the dilution factor F at the measuring point becomes

N

o

Equation (1) has been proved by the standard convolution technique.

The method, which i s a shortcut to the use of continuous injec­tion, has been eaployed for a flow rate of about 3a fmia and dilution

—4 —5 down to the range 10 to 10 . The act ivit ies employed were reasonably low and range froa a few nCi up to a few tens of s£ i Kr par injection.

THE USE OF RADIOISOTOPE TRACERS IN THE STUDY OF THE DISPERSION OF SEWAGE AND INACTIVATION OF BACTERIA DISCHARGED INTO COASTAL WATERS: Ch. Gilath, S. Horowitz and S. Blit*

The s tudy o£ sewage d i s p e r s i o n and r e s i d e n c e t i a * i n th« e s a *

was cont inued a t Raading (Te l -Av iv ) o u t f a l l . Tha i n v e s t i g a t i o n s : v a r a

a l M d a t determining t h e d i s p e r s i o n p a t t e r n , f i t t i n g t h a r e s u l t s t o

e x i s t i n g d l spara lon a o d e l s and prov id ing data f o r tha dataradnatloD

o f b a c t e r i a d isappearance k l n a t i c s .

Tha b a c t s r l a c o n c e n t r a t i o n I n tha lawags f i e l d I n tha M a was

supped a t s e v e r a l depths f o r d i f f e r e n t wind and s e a c o n d i t i o n s . I s

c o l l a b o r a t i o n wi th v a r i o u s p u b l i c h e a l t h l a b o r a t o r i e s . Chengee i n

b a c t e r i a c o n c e n t r a t i o n were a l s o aeaeured s e a f u n c t i o n o f t h e t i r *

o f day* Empirical c o r r e l a t i o n s v e r s found f o r t h e b a c t a r l a c o o c e a t r s -

' GraduiM School, Walimann Intt. of Stitne*.

- 106

tlaa as % finecion of the position of thi cloud, distance and position of tin sampling point from the sewage boil and depth of sampling.

Two radioisotope tracer experiment* (fall 1969} were performed fl 2) using the instantaneous injection Method1- * ', Simultaneously sea

currents and bacteria concentration measurements were taken. Unfortunately, both tiaes an unfavorable western wind was blowing which threw the cloud on shore. The sewage travelling time from the boil to the shore was very short (about one hour) and only limited information could be obtained. It was therefore decided to perform two similar experiments using the continuous injection method.

About 1.5 to 2 Ci/h Br was injected into the sewage at a constant rate for 3 to 4 hours. The injection is actually a. rectan­gular pulse sufficiently long to permit the establishment of steady state conditions in the sea. The activity was continuously mapped at cu> depths. It first grew to steady state level and then decayed when the injection was discontinued. Dilutions were determined directly from the steady state concentration while other complementary -information on the flow pattern in the cloud was determined from the transient part of the activity mapping. Sewage residence time was deceraineci fron simultaneous current measurements using drogues or dyes.

It was found that bacteria disappearance plays a relatively Important role in the overall mechanism determining the bacteria concentration along the shore.

References: 1. CILATH, CH. and STUHL, Z., in 1A-1190, p. 207 (1969) 2. GILATH, CH., SUUVAL, H.I., FUREX, Y.Y. and COHEN, N., Proceedings

of the Jerusalem Conference on Water Quality Research, June 1969 (in press).

CONCENTRATION DYNAMICS IN A LAKE WITH ,'* WATER CURRENT FLOWING THROUGH IT: Ch. Gilath.

Large water reservoir with volumes of millions of cubic meters, e.g. artificial or natural lakes, are a common feature of large water supply systems. The quality of the wster at the outlet of the reservoir (usually near to the consumer) is determined by the incoming water and the dynamic response of the lake. The residence time distribution of the water flowing through the lake influences the water quality via the kinetics of aerobic oxidation processes, floculation, sedimentation, etc.

A study was performed on the Eshkol Lake of the National Water

- 1*7 -

Carrier. Tlie mean hold-up t l cc of tno lake [ I . e . volnza it -K-cr i.r. the lake divided by the flow rate turou,;. lt> Is alnoac 3 days. pulse of ac t iv i ty (about 15 curies *«r) vaa injected at t.ic inlet :o the lake, and the ac t iv i ty at tnc outlet -/as continuously ror.itorcd for over a week. Luring this period, cite act ivi ty in ths la^e ^as mapped every day and measurements ucre taken at various depths. A s t r a t i f i ca t ion phenomenon was observed and checked by simultaneous temperature profile neasurenents.

The resul ts --'ere processed into a transfer function for the lake ( i . e . input-output concentration relation) for the conditions prevailins during the experiment. Furthermore, the frequency response of tne system uas calculated. This was found to be of great help for water quality control purposes. Finally the residence t ine d i s t r i ­bution of the water flowing through the lake vas determined.

THE USE OF RADIOISOTOPES FOR MEASURING THE SEDIMENT MOVEMENT IN A SMALL WADI: Ch. Gilath.

The study of sediment movement in Vadi \'ael vas continued,as part of a project of the Geooorpliological Laboratory of the Kebre-j University.

Irradiated ciiroraiua--hearing glass par t ic les (2-3 tss diaseter) uere used as a sediment simulator. The ac t iv i ty injected durlnj each of t*jo floods in the 196B/69 -mincer was about 1 curie Cr and could

4 2 have been traced over an area of about 10 m if homogeneously spread and not buried. In both cases i t was found that under the given conditions of grain size and location of the injection device in the wadi, the slass par t ic les noved only about 30 neters froa the point of re lease. Host of the act ivi ty was trapped by nlcrotopojraphic

(2) obstacles . 1'he work is beins continued.

Reference: 1. STUI1L, Z. and CILATH, Cli., in IA-1168, p. 124 (1968) 2. GILATK, Ch. "Tracing of silt novamant by the usa of Radioisotopes"

(in Hebrew), paper delivered at the 2nd Annual Conference on Siltation Problems", Jerusalem, June 1969

RADJOBJOLOGY AND MEDICINE.

The research conducted in radiobiology and cedictr.e Is concerned with basic and applied studies on radiation effects on biological systems, and Che development of nethoda for clinical diagnosis and therapy by use of radioisotopes and other radiological devices.

Much of the work is being dene in collaboration with various agricultural and medical centers, as reflected in the reports given below dealing with radiation effects on insect development, cancer research, the development of new radiation-protecting cheaicals, and studies using the whole-body counter to investigate iron deficiancy anaemias, neuro-muscular diseases, and uremic states as reflected by potassium intake.

The research program also includes studies on UV-irradiated nucleic acids (reported below), as well as other studies still in a preliminary stage, such as radiation effects on plants and tissues grown in culture, indirect effects of radiacion, and effects of radiotoxines formed in irradiated foodstuffs.

EFFECTS OF DOSE AND TEMPERATURE ON THE FORMATION OF PHOTOPRGQUCTS

FHOM UV-1RRAD1ATED DNA: J. Krarror and E. Rihlis. Three main dimcric photoproduct^, viz. thymine dUier, uracil

diiner and uraci l thymine diner t have been separated frcci D*>A aolut icr-a irradiated by UV lig.it a t roca teu^erature . In t re present seedy the effect of dose and temperature on Che formation of the piiotopcocucts was studied. Since heating Cite DNA above i t s r .eltic^ point -.ighc ciian^e i t s secondary and te r t ia ry structure, etcher intrasrrand reactions or reactions with the solution =ay result ' , which vcuie affect tue photoproducts.

A 0.015 M NaCl solution of L. col i mis label led with thyaiae-2 k C , was UV-irradiated a t temperatures iron 23° to 95°C, and coses frca

5 7 2 1.5*10 to 1.5*10 ergs/cci , using a high pressure cercury l a rp . After acid hydrolysis and chromatographic separation on '.Miatnan ;:o.3 paper in a solvent system butanol:acetic acid:water - 200:30:75, a new radioactive photoproduct with Rf=0.39 to 0.42 was found. I t is

6 7

referred to here as Dl* At a constant i r radia t ion dose (3.3*10 erg/s=T), the formation of photoproduct Dl increased linearly with the tenperature in the range studied. In contrast , the fomation of thymine -imer

(2) decreased at higher temperatures . At constant cenperacure (S5'C) the yield of Ul increased l inear ly with the i r rad ia t ion dose, while the formation of thymine dimex became dose independent at re la t ive ly low doses.

Quantitative elution of photoproduct Dl froa the paper and rechro-uatogrophy in the solvent system ethyl acetate:foraic acid:water - 7:2:1, revealed that Dl could be further separated into two radioactive peaks, with Elf values of 0.54 and 0.75. The peaks were designated D2 and 03 respectively. 02 showed maximal absorption at 260 not, the absorbance decreasing upon reirradiation in solution. D3 showed no absorption at 260 ma. D2 formed a pale yellow color with PDM3 (an alcoholic solution of p-dimethylamino benzaldehyde) while D3 showed a strong yellow spot, indicating a positive test for a ureido group. D3 had a similar Rf value to urea In different solvent systems, and gave a positive Kesaler test, indicating that D3 is probably urea. Further work is being done to Identify both photoproducts unambiguously. References; 1. SETL0W, R.B. and CARRIER, W.L., J. Mbl. Blol.l£» 237 (1966) 2. H0SSZV, J.L. and RAH1J, R.O., Bioph. Res. Count. 29, 3, 327 (1967) 3. BEN-HUR, E. and BEN-ISHAI, R., Gioch. Bioph. Acta 166, 9 (1968)

P H O T O M O O U C T S OF FROZEN THYMINE SOLUTIONS IRRADIATED BY UV LIGHT: Zl. C*«iuli*i E. R * * and G.MJ. Schmidt*

frozen thymine solutions irradiated by UV light has been found Co be closely related to dese and wavelength, of irradiation, thymine concentration and cycles of freezing and thawing ' * .

Techniques for isolating and identifying the photoproducts were developed* . The isolation is performed in two stages, the first based on solubility differences and the second utilizing chromatography. Altogether eight photoproducts, designated F-Z to P-VTII, were separated. The condition* for maximal yields of particular photoproducts vary. For examples, p-l is best obtained by irradiation of relatively

6 -2 ; moderate UV doses (1x10 erg mm ) whereas P-V, P-VT and P-VXII are

am dilute solutions 7 -2 (1x10 erg ma ) filtered through a NISO, solution.

Toe structure and properties of four of the products have been elucidated by nixed melting point, «4R, UV, IR, and X-ray powder diagram techniques: a) P-IV - the structure is tentatively proposed as the cls-anti dlmer of thymine, on the basis of chromatographic properties, UV absorption and photoreverslbillty to thymine by UV irradiation in solution, thermal

(31 Instability in solution, and photosensitized splitting to thymine . The X-ray powder diagram and IR spectra will be compared with those of an authentic cls-anti dimer. b) F-V - chemical and physical properties similar to those of standard

14 urea. (Mot obtained as a radioactive photoproduct from methyl-C thymine). c) F-VT - chemical, pbotoohemical and physical properties similar to those of standard dihydrothymine. d) F-VZII -chemical and physical properties similar to n-propylurea. e) Of the other products, P-I is unknown, P-II has betn shown to be the cis-syn dinar, P-III an adduce, and P-V1I thymine.

The observations are tentatively interpreted as an Indication that the dlmers and other photoproducts formed are photochsmlcally unstable In the concentration ranges used and are photodegraded further. The alternative explanation that at low thymine concentra­tions a sacomd photoactive species Is formed (as an alternative to thymine monohydrata*3') leading directly or indirectly to dihydro

- 193 -

thymine, cannot be ruled out at this stage. Attempts are being aade 14 to correlate these results with studies carried out with cethyl- C

14 or 2 C-thymine labelled DNA and polydeoxythymidylie acid in which several nonindentifled photoproducts have been obtained by high UY Irradiation doses . It aeons logical to assume that the cost prominent effect of UV photodegradation of thymine in single stranded UNA (or melted double stranded DHA) occurs in such conditions where the helical structure collapses into random coil. References: 1. CAMNTCHIK, Z . I . and RIKLIS, E. , in IA-1190 (1969) p.255 2. RAllN, R.0. and HOSSZU, J .L . , Photochem. Photobiol. , JLO, 131 (1969) 3. CABAHTCHIK, 2 . 1 . , RIKLIS, E. and SCHMIDT, S.M.J., I s rae l J . Chea.

(in press) 4. WACKER, A., "Molecular Mechanisns of Radiation Effects", in Progress

in Nuclei Acid Research, J.N. Davidson and H.E. Cohen, eds. Vol. 1 , , (1563).

THE EFFECTS OF IONIZING RADIATION ON THE EMERGENCE OF ADULT C MACULATUS FROM INFESTED GRAINS: A. Naharin and M. Cakfcron*

The work on the suscept ibi l i ty of store-pests to radiation ^as continued. The influence of sublethal doses on C. naculatus Has studied to determine what effect such radiat ion doses have on the l i f e cycle and how sublethal doses may affect the ultimate degree of eradication.

Groups of 50 each, from a l l developmental stages (eggs, larvae, pupae and adul t s ) , were irradiated at 3 different doses at a dose-rate of 262,000 radaVh. The time which elapsed before emergence of the adults fro* the seeds was observed. The c r i t e r ion for eva­luation of the change* in the l i f e cycle of the insect was the "50% emergence period".

Figure 1 shot's the retardation in emergence in re la t ion to the dose' In the 4 developmental stages. I t can be seen that retardation i s approximately proportional to dose. Eggs were found to be the most sensi t ive s tage, as the ainimun dose of 250 rads caused a retardat ion of 10* In aaarstnee time, while a doae of 1000 rads caused a 92.51 retardation compared with controls . The larval stage shoved 2.3% retardation at tha ninlmvm dose of 500 rads and 78X at the highest dose delivered, 2000 rads. The pupae showed no retardation up to 3000 rads, but-28%,retardation was achieved with a dose of 8000 rads. The adults, which <»r* the most resistant state, vera given * vety wide range of doses, from 2500 - 160,000 rads. The threshold dose was found to be approximately 10,000 xads.

* N«it f rottctton DbMsft, MintaWy of Africullurt.

- 1 9 4 -

Log dose (rod) Fig. 1

Delay In emergence of adult C. maculatua from the seeds At doses of 40tQ0Q rads and above, an Interesting reversal in the

retardation phenomenon occurs,turning i t Into a "shortening" of the 507 emergence period. At the maximal done of 160,000 rads the shortening of the emergence period was 76.8Z. This phenomenon may indicate a "desperate" attempt of the Insect to complete i t s l i f e cycle as quickly, as possible as the doses become higher. Reference: 1. XARARIH, A. and CAMERON, K., IA-1010 (1965)

COMPARISON OF RELATIVE UPTAKE OF GAMMA EMITTING RADIONUCLIDES BV SOME LOCAL AQUATIC PLANTS: T. Stdsh and A. Tal.

Toe research on ion-uptake of water plants^ ' was continued. Radionuclide uptake was correlated with the kind of sample investigated and the location from which i t was taken.

The plant specimens were collected at various points £ror the optn reservoirs of the National Hater Carrier. They 1Beluded higher plant species, such as Potamogeton (e .g . F.perfollatus, pectinaCus and nodosus) Ifsjae, Nyapliaes and various sedges, and lower plants, such MM the algae Nltella and Giara. Mud and water samples were also taken. The samples collected were dried, ashed and the ash analyzed for radio­act iv i ty .

The radioactivity determined was from y-e a i t ting nuclides commonly associated with fallout^ naturally occurring long-lived radio­active elements, aud uosaogenlcally produced short-lived Y~«*itters,

Concerning the distribution of the radioactive nuclides in the

samples, the following conclusions may be drawn. (2)

a) ttatural long-lived isotopes Pocasslum-40: Potassium, an essent ia l plant nut r ient , accumulates to a considerable degree in the higher, phanerogamous water-plants , such as sedges, potamogaton species, and Najas. I t becomes concen­trated to a considerably smaller degree in the lower water-plants. Bottom mud does not seem to be enriched in. K-40 despite i t s abundant microbiological f lora .

Katural uranium and Daughters: Natural uranium and i t s decay products were found in most of the samples tes ted. Distribution seemed to be random and low In concentration i a the samples measured.

Thorium-232: This nuclide was s l igh t ly less frequently encountered than uranium. The measured radioact ivi ty was d i s t inc t ly also less than that of natural uranium. No speci f ic absorption by any of the tied water-plants investigated could be discerned b] Isotopes derived from f a l l - o u t * "

Cesium-137: Unlike pctaasiun, this a lka l i metal does not seem to become enriched specif ica l ly in the higher ^a te r -p lau t s , although i t was found in roost of the samples investigated.

Ceriuia-144: This rare earth isotope was frequently detected in the samples, but no sign of specif ic enrichment could be discerned.

Zirconium-Niobium-95: The distr ibution of these radioelements closely resembles that of ceriua-144.

The re la t ive shore lifetimes of Sb-125, Bh-106 and Be-7 did not permit an estimation of the frequency of occurrence, although they were detected in some samples. References: 1 . SHAIMffi*, E . and SADEH, T . , i n : I A - 1 1 9 0 . 1 9 6 9 , p . 2 4 1 2. BOHEH, H.Y.M., Tract Eleatnts in Biochaaiatry,Academic F n s i , 1966,

p.173-210.

GASTROINTESTINAL ABSORPTION OF ««Ca IN SUCKLING MICE: A. Naharin, Y. Ftioa and E. Lubin.

(1 25 In previous studiaa * wa ihowad tht trana*ar of lanthanidta fron contauinatad Bice to their offspring through placental transfer

144 and by Buckling. The percentage of - Ca absorbed froa the gaatro-intastinal tract during tha suckling pariod was found to ba va i l over 12, ona to two ordara of magnitude highar than tha acceptad -values for gastrointestinal ahaorption of lanthanides in adult i i—ale .

- 196 -

'J* timniow coadwcted another ser ies of experiments la order to evaluate lm more deta i l th« cuaagealn the absorption of Ce by the gaetroi*t**tUal tract i n suckling a lee during the f i n e ueeks of tae ir l l f « .

itotfters were injected "lth W * C e c i t ra te immediately after delivery. Sally whole body counts of the suckling l i t t e r s t-ere

144 performed. Aacopsies were performed at various ages end the Ce act iv i ty Inside tne gastrointestinal tract was compared to that found i n toe l i v e r and i n the carcass.

144 Though toe daily intakes of Ce through milk, remained unknown became the excreta could not be col lected, we nevertheless were able to derive gastrointestinal absorption values froa the whole body and aotops7 coants. Preliminary -values for the gastrointest inal transfer

144 of Ce are presented in Table 1.

The discriminatory ability of the gastrointestinal tract is lowest on toe first day after birth, and then increases with age. .Additional experiments, to obtain improved statistics, are in progress.

TABLE 1 Gastrointestinal transfer in suckling mice

Ax* of l l t t a r lfl daya X absorption froa tb* G.I. t n c t

0 - 1 2 - 4 5 - 9

10 -15

45 *20 8 £ 4 5 ± 2

•* 2

P.«f«ranc«a: 1. 1UIIK, E. and IWEAMB, A. , Int. J. Ajipl. Eadlat. Iiotopta 17, 301

(19M). 2. ;rAI!*5E!, A. , UJEIH, E. and PIICE, Y. , Utalth Fhya. 17, 717 (1969) 3. DUMIH, P.V., WIILIAMS, K.M., OK, M., MBMAH, R.H. and HAMILTON, J .O. ,

froc. toe. Exp. Biol. Hrd. 91, 7a (1956).

MODIFYING THE SURVIVAL OF IRRADIATED RATS BY PNEUMOTHORAX: JA. 5 s J: M. Dufaranki*. E. Llban", Y. Foige and M. Bwpr*

The relat ively higli rauioaensitivity of pulconary t issue i s a limiting factor in effective radiation therapy o( nallgnaat asaplasm located Inside the lung or adjacent to i t . t-Tiereaa the majority at hunan tumors require a therapeutic dose of 50QO-60OO rads , the lust; t issue usually to lera tes only about 2000-3000 rads. Beyond th i s dose acute radiation induced pneuaenltls i s l ikely to occur, which i s followed in many instances by fibrosis of the affected region. The high radiosensi t ivi ty of lung tissue could in part fce dxie to I t s spongy structure and rich supply of oxygen.

The object of t h i s wotfc was to determine experimentally the possibi l i ty of raising the resistance to i r radia t ion of pulconory t i ssue in the ra t by uni la te ra l left sided pneumothorax pr ior to i r radia t ion. The codification, of conditions -within lung t i s sue following the expulsion of a i r from the lung nay resemble other organ t issues more closely with regard to the effects of irradiator!.

Survival time following irradiat ion of t i e ent i re chest u i th sublethal and le tha l doses was chosen as a cr i ter ion of the degree of radiation daaage. An increase in survival was found in the ra t s receiving 2,000 rads with uni la te ra l pneumothorax (see Fig. 1 ) . This finding stay be taken as an indication of a radiation protective effect of lung t issue compression.

-r-r _T_ T " T - nr Controls

don ' 2000 radi .

1 ' '_ ' ' ' il_ ' ' ' 2 0 4 0 6 0 8 0 WO C O 140 Doyi 0(Hr irrodiofcy.

Fi«. 1 Mortality curves of r a t s following 2000 rads i r rad ia t ion

of th* ctv*tc, with »nd without uni la tera l pTwwmothorax

Th , Innrnm of Oneototy *nd nadtoltoMf**. T«t-Avh» OntvwKy MMHCM Set**!, Harfonh HwpI«I.T«Mviw.

* Oapt. of ?*hotaw. KapUn HIMPIW, fuhoiot.

At POTWTIAL MOtOMWTECTlON MEMS:

bava alEMif baaa Isoaatliatad ao " ' . Hi taa atadr outllaad tan,

J aaaatUaaad aalaaaaalldlaaa* ' aara prcparad and aza to ba taatad aa •atl-raatatla* aaaara. Ihaaa rifnai i l i ata eloaaly aaalogona to cha b a m litaaaHdlaai' . Slaca aalaalaa coapoaoda h m a prevail radical aiaiaa. lal capacity vbich axcaada t i a t of the corraapondlnf •a l tar darlvatlvaa by aavaral ordara of •agirttaoa* S i t adght ba faaalaj* b> aaplajr aalaala* baaxtaa; cbaalcala l a radloorotactlou aaaaita tae blab toxicity of orjaao-ielaalcala' ' .

Xa tba eoaraa of tbl* raaaardi tae follOHiae: ccapoonde vara araeared aa deai rnied.

1) JeleaocTataerfaa vaa aroeeced bj three different eethode' ' I s eceer to detenlae tee oaa aoat agitable fox preparlne aelenocyetaai-aa rnarafalae, radto-eeleatea St. Iha eetbod of FJaraan* ' vaa adoeted.

2) Salaaaaolidlaat aot coatafalng add le or tiaeic functional groove aara ateaarod ay raaaettom of •eleeocretaelBa vith aodloa borobjdride to aaleaocyate—fao in water, aatsaool or acoaooX at an alfcal-fne pS, aftar eelcb I t vaa eeutralliad with BC1 aad than treated vita an eppro-prUte carkoejl coapoead. Iba aalaaaiolldlaaa vara leolatad In tha free- atata or aa ajratocUorlaa aalta.

Mferaeeae. i . mata, t. mi TOOL, i .e. , tediat. «... u , 210 <««•) 3. MUOBt, a. mi U U B , r., froe. l e n e l J . Cbaa. 7, 10 <196») 3. amzaa, k. aad mamm, A.D., bdut. Ua. i».~23 <W6i) a. a m - M I OD aadKltfiSeX, I .O. , J. O n . Cbaa. j fTMM (1962) 3. k v n , 0 . 1 . , ad. , fjraaoolaai Seleaiaa l a l ioaadlciae. Section III

Xeeieltr, ..127-1S9, Raataort, Coaa., .1*1 roMiablag Boon, 1947 «. C a m m , W.I.g. aad KJUFTHM, H.C., J. Had. Chaa. 7, 229 (1964) 7. ORBaV » . • . ! . , J . Org, Cbaa. 3 | , 3t2* (1S*7> *. n n u i , D.L., j . org. Cbaa. JO, MS4 Cl<65)

- I'M -

GROWTH INHIBITING EFFECTS OF CYTOTOXIC AGENTS ON HUMAN TUMOR AND TUMOR-BEARING NORMAL TISSUE IN-VITRO: CLINICAL APPLICATION: F. Ch. Inek* 6. Eytan**. A. G w i t h " , J. Shapiro". A. Naharfn, Ch. R a i r j n l "

Cancer c h e c o t h e r a p y La based ma in ly on knowledge d e r i v e d txoa

e m p i r i c a l o b s e r v a t i o n s of many c a s e s . In s p i t e of t h e e x t e n s i v e

accumula ted e x p e r i e n c e , t h e r e a r e p a t i e n t s uho do n o t b e n e f i t f r c a t h e

use of c y t o t o x i c ager.Cs b e c a u s e of i n d i v i d u a l d i f f e r e n c e s i n t h e

s e n s i t i v i t y of t h e tumors and of t h e e n d l e s s v a r i a t i o n , f r o a p a t i e n t

t o p a t i e n t , o f t u m o r - h o s t r e l a t i o n s h i p p a t t e r n s . In a c o s h e r of

i n s t a n c e s , c y t o t o x i c a g e n t s have even been shovn t o s t i m i l s t e t c c o r

g r o w t h .

A s tudy was performed on human t u a o r t i s s u e s and a d j a c e n t no rea l ,

t i s s u e o b t a i n e d from t h e t u m o r - b e a r i n g o r g a n ^ t o o b t a i n a r a p i d c l e a r -

cu t r e s p o n s e t o c y t o t o x i c a g e n t s , and a l s o t o e s t a b l i s h w h e t h e r t h e

r e s u l t s o b t a i n e d cou ld b e e a s i l y a p p l i e d t o t h e p a t i e n t .

The i n h i b i t o r y e f f e c t s o f f i v e a c c e p t e d c y t o t o x i c a g e n t s on t h e

i n c o r p o r a t i o n of F-32 i n t o t h e n u c l e i c a c i d s of c a n c e r t i s s u e and

a d j a c e n t normal t i s s u e were s t u d i e d i n s h o r t t e r n t i s s u e c u l t u r e s .

The method i s b a s i c a l l y t h a t of Ambrose . F o u r t e e n u n s e l e c t e d

p a t i e n t s , 11 u i t h b r e a s t c a n c e r and t h r e e u i t h c a n c e r of t e g s t omach ,

were s t u d i e d . I n t u o c a s e s t h e r e s u l t s o b t a i n e d i n t h e t i s s u e c u l t u r e s

were a p p l i e d t o t h e t r e a t m e n t of t h e p a t i e n t s .

B r e a s t Cancer : The i n c o r p o r a t i o n a c t i v i t y o b s e r v e d i n 11 c u l t u r e s

o b t a i n e d from b r e a s t c a n c e r was found t o be low. The I n c o r p o r a t i o n

a c t i v i t y of t h e normal t i s s u e i n a g i v e n p a t i e n t was s i n i l a r t o t h a t

o b s e r v e d i n t h e c u l t u r e s of t h e tumor from t h e same p a t i e n t . T h i o t e p a

p roduced a ve ry good r e s p o n s e In two c a s e s , a goo:? r e s p o n s e i n 4 c a s e s ,

w h i l e t h e e f f e c t was p o o r i n t h e r ema in ing 5 c u l t u r e s . Harked

s u p p r e s s i o n was o b t a i n e d i n t h e normal t u a o r - b e a r i n i ; t i s s u e i n 1 e a s e ,

m o d e r a t e s u p p r e s s i o n i n 4 and a poor a f f e c t was s e e n i n 6 c a s t s ,

Xt s h o u l d be s t r e s s e d , however , t h a t t h e r e was no c o r r e l a t i o n be tween

tumor t i s s u e and i t s h o s t t i s s u e w i t h r e g a r d t o t h e i r r e s p o n s e t o t h e

c y t o t o x i c a g e n t s added t o t h e c u l t u r e c e d i u n .

Stomac':> Cance r ; The i n c o r p o r a t i o n a c t i v i t y o f b o t h t h e tumor and t h e

normal s t o u c h t i s s u e was i i i g h e r t h a n c h a t s e e n i n t h e b r e a s t t i s s u e .

Hera t o o , a h i g l i l y i n d i v i d u a l p a t t e r n c h a r a c t e r i s e d each tumor .

Our o b s e r v a t i o n s s u g g e s t t h a t a d e t a i l e d s t udy i n e a c h c a n c e r

* Donoto OoMfnnwnul Hotpful, Jaffi.

"Unhmtltvof Tti-Aviv.

.200-

•eeiemt i* M O N M I T . Oesly isrg« scale correlative studies of th is •scare may f l taUy allow ma to imach meaningful conclusions containing tarn peeelbll lty of em la v l t ta t f i t M capable of predicting in vivo

I , | , J „ , A»UVS, I .D . , sad EASTl, O.H., Brit. Hed. J , , T, 400-1 ( U M )

UK OF *"I-LABELLED ROSE BENGAL FOR DIFFERENTIAL DIAGNOSIS OF JAUNDICE: A. »iiilai«i,»C WiiiiiMi, N. awuTmd J. Krswstz*

A method, w i developed for rapid examination of the bil iary trace la cases of seriow* jaundice or abnormal l iver function. In these cases fit I s usually impossible t o use X-ray or other laboratory testa for th is purpose. In the present method rose bengal- I i s injected intravenous­ly and I t s excretion into the bi l iary ducts after having been absorbed by the hepatic c e l l s is followed. The substance CMU be traced up to the b w c U .

This method of scanning was successfully used to diagnose l iver laeufficitacy, obstructed biliary tract (extra-hepatic and intra-hepatic), protracted c u e s of Jaundice i s children, and hepatic Gilbert di sease. The method I s easy to use, affactive, reproducible and not dangerous, as confirmed by the results in the 70 casea examined.

US€ OF WHOLE-BODY COUNTING IN ANEMIA WITH IRON DEFICIENCY: E. Schachnet.

Three petieaCs with suspected anemia have been examined by 59 administration of Fe followed by whole-body counting, Hie dose

59 of Fe was about 5.5 u&, given per os.

Case 1: Hiis patient had hypochromic anemia with 9.5 g hemoglobin and 2,930,000 erythrocytes. The retention of the 5 9 F e after 5 days was found to be 23.7Z. This indicates an

59 increased absorption of Fe, leading to the conclusion of anemia becatm* of iron deficiency*

Case 2: A patient after gastrectomy had 10.7 g hemoglobin and 3,550,000 erythrocytes. The retention of Fe after 11 days was 11,72, i . e . normal absorption. This la probably a case of nutritional iron deficiency due to diet .

A g i r l 14 ycers old with celiac syndrome showed 0,94% retention of S 9 F e small absorption.

59 retention of 'Fe after 7 days, uhlch indicates a very

- 20! -

The procedure dcsctlbad above la a ulcple way of MtaMlaiil.ig the various aspects of ancala caused by Iron deficiency.

BLOODSTREAM BACKGROUND SUBTRACTION I.N RENOGRAPHY M. tlzot.

In renography baaed on labelled hippuran tracing, It Is deoirabie to subtract the contribution of tracer In the blood froa the to cat measured activity in order to find the tracer accumulated and evacuated by the kidneys. For this purpose a radioactive tracer which Is noc accumulated and evacuated by the kidneys, e.g. RIESA, is first injected into the patient and the activity in the kidneys is cc=?ared with that in the region of the heart (where the blood concentration is high). A dose of hippuran is then injected and tha radiation in both regions is again ceasured. Knowing the ratio k of activities in the heart an' Sidney regions it is possible to calculate and subtract tfae contribution of radiation coning froa the blood in the kidney region. Thus weak kidney activities which would otherwise be masked by the activity of the bloodstream can be ceasured.

A set-up for these measurements jonprlsing a digital recorder and digital computer for subsequent data processing has been described The disadvantage of this system is the complication of the equipment and the delay between the test and the computed results. He have th refore devised an alternative method, based on analog rather tvin digical instrumentation.

The arrangement is shown schematically in ' s-1* Tw* conolithic operational amplifiers A- and A, , of the type uA 709» are connected In such a manner that the ouput signal c is proportional to the difference (a - kb), where a and b are the voltages representing the radioactivitv in che heart and kliney regions respectively. A- serves as an inverting variable gain amplifier permitting k to be chosen in the range 1 - 100. A- performs the summation of a and -kb. P.. serves for continuous variation of k and S for stepwise variation of k . r\, and P 3 permit zeroing of the two operational amplifiers. Two information channels are recorded on a strip ^hart recorder; I represents the difference (a - ih), i.e. the net kidney contribution and II represents the combined (blood sod kidney) contribution.

This work was carried out in cooperation with Dr. Silberoan of

the Negev Hospital.

FROM MTBCTEKZ h ^ | • » * nocvsi

Arrangement for bloodstrei Fig. 1

i background subtraction in renography

1. BROWN, N.J.A. and BUTTON, X.E., The Renograa and I t s Quantisation, Proc. Symp. to Review the Dses of Radioisotopes in Urology and Renal Disease, Institute of Urology, University of London, Oct.1968

A CASE OF INSOLUBLE NATURAL URANIUM CONTAMINATION. A TWO-YEAR FOLLOW-UP STUDY* 1': M. Ronen and E. Riklii.

The urine analysis and lung-burden of a laboratory worker who '.iad suffered accidental uranium dust contamination was followed during a two-year period.

Ac flr.it the urine was tested daily - and sometimes thr<M times a da/. Later i t was tested on three consecutive days each month. Hie amount of uranium found varied from 60 to 4,000 pg/1 at f i r s t , and frot* 20 to 4,00'J pg/1 after 2 years.

Following Coflcld's method, direct lung measurements were also made In the whole-body counter. The estimated lung-burden according to tiiat method was: 210 ug at 5 months after the exposure, dropping co 110 ug at 0 months, 61 mg at 1' year and 52 og at '2 years.

As the aoount of uranluu in Che urine sometimes reached 4,000

- 20) -

gg/1 even after 2 years, there daea not actio to be a atcplc comai-aiiaa between the urine excertion of the uranium and the lung-bucisn.

Reference: 1. ROHEN, II. and RIKLIS, E., Syc*>. on Handling Radiation Accidtne*,

Vienna. May 1969.

A STATISTICAL SURVEY OF POTASSIUM CONTENT IN THE HUMAN BODY, BY WHOLE-BODY COUNTING: C. Silbtrman.

A pi lo t experiment uas conducted in order to obtain s t a t i s t i c s on the potassium concent of the hunan body. The subjects -*ere 202 employees of the AEC laborator ies , grouped according to age (20-29, 30-39, 40-49 years) , as well as according to country of origin (:.'orch Africa, other s ta tes of Africa, usia, Western Europe, I s r ae l ) , and duration of employment a t the laboratories.

A marked decrease in potassium content was round froc one a^e group to the next, with 1.90, 1.80 and 1.67 per kg respectively in the three age groups mentioned. Ibis i s in agreement */ith f ind ing published in the l i t e r a t u r e . Persons Eron iisia and Africa (except North Africa) shoved a pronouncedly higher concentration of K than those from other countries (l.SS vs . 1.79 g/kg). AQ significant influence of the time of employment uas found.

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HEALTH PHYSICS.

Activities in the field of Health Physics cover several applied and theoretical copies such as radiation dosimetry, personnel oonitorlng, environmental monitoring - including radioactive fallout evaluations , development of specific radiation detectors and instrumentation, waste disposal, and decontamination. Preliminary results of work carried out on some of these topics are summarized below.

RADIATION SAFETY WHOLE BODY COUNTER: A. B m Haim and Y. Feige.

The design and construction of a reduced-shield hunan counter to be used as a personnel monitor for internal contamination and as a low level counting facility have been completed and the counter is at present being installed.

The matched detector assembly includes a 9" dia x 3" thick Nal (11) crystal with quartz optical window and aluminium entrance window coupled to 4 phototubes selected for low background. The counter consists of a 10 cm thick lead shield and a notorized couch which can

be moved on rails underneath tt.e detector castle. This scanning set­up, with a fixed detector and novable subject, reduces the amount of shielding material to about 10Z of that requited Eor a steel Cor lead) room, without any loss in efficiency. Furthermore, it conslcerably reduces the air volume "seen" by the detector and therefore minialzes the contribution of airborne radon daughters to the background*

Besides use as a monitor for Internally contaminated personnel, the counter will also be used for long terra retention studies of radioisotopes used in medical diagnostic procedures, and in other biological and clinical research problems.

LONG-LIVED RADIOACTIVE FALLOUT IN ISRAEL: I. Proulov, D. Karp. Y. Feige and Z. Biumankrantz.

Collection of fallout data from nuclear detonations was continued during 1968-9. Measurements were made of radioactivity in air and of deposited activity, including that In precipitation.

137 90 The gradual decrease in tha levels of Cs and Sr observed during previous years ceased towards the beginning of 1968, and the I960 levels were generally sooeuhat higher than the corresponding 1967 values (see Pig. 1). thia is in line vieli the significant increases in the stratospheric inventory of long-lived fission products result­ing fro« the 1967-8 Chinese and French atmospheric nuclear detonations .

The averac.fi Cs/ Sr ratios In airborne activity decreased to about 1..1, indicating that the increase in Sr levels relative to previous years vas somewhat greater Chan the corresponding increase

;[onttiXy K3an values of Sr and Gs concentrations in ait in Israel, 1U65-1369

1. Report of the UHSCEAR 24th Session Supol. So. 13 (A/7613) United lotions R.Tf. 10S8, T>.U

, 3 7 Cs and 9 0 Sr LEVELS IN FOOD: I. Proulov, Z. Blunwnkranta. Y. Feige, R. Padova, A. Eisenberg* and D. Karp.

the assessment of the degree of contamination of various food itea* in Israel with Long-lived radioactivity was continued. The

Cs and Sr concentrations in food (pc/kg), as well as the average daily intakes, are ausoarlzed in Table 1.

There was a t i l l SOP* decrease in the levela of contamination compared with thoie for previous years (July 1965 - June 196a)^ 1»Z^ 1

despite the increase in local fallout values (see preceding art ic le ) . The average Individual dally Intake via food during the year Mas about 22 pc U 7 C s j a l 7.5 pc 9 0 ,

. 137,, The *eln contributor* to the * J'C> body burden a n bread, aeat and the beverages - tea t coffee and cocoa. Because o£ the wide varia­tion In the Ce concentration! In these products and the large differences In Individual intakes, according to dietary habits, the daily 137... Cs intake will ot course vary considerably from one indivi­dual to another. Sr values are generally much lever tlian the

137 correspond!:* Cs concentrations, except in cheese.

The svaraga dally excretion of 1 3 7 C e as deteninsd by bloassay front n o n e l "uacontamlnated" subjects was 22 pc/dsy (rsnga: 15 - 30). This figure matches average intake eatiBatea.

Ministry of Health, Jerusalem

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1 . FiilGE, ¥ . . PR0UL0V, I . , SliALKOX, E . , EISENBEKG, A . , and P0NAGE, A- , H e a l t h P h y s i c s R e s e a r c h . A b s t r a c t s N o . 2 , IAEA Vienna ( 1 9 6 9 ) , p . 1 3 2

2. PROULOV, I . , FEIGE, Y . , SliALMO'l, E . , EtSENBERG, A . , and ULK-IENKTRANTC, 2 . , IA-1190 (19&9) R.238-9

INFLUENCE OF FLOCULENTS ON THE DECANTATION OF NEUTRALIZED RADIOACTIVE WASTES: S. Agam.

floculents t*ill, when properly applied, drastically change the oecautation tine in precipitation. As neutralization and decantation. are the first steps in liquid waste treatment, it was of interest to determine the possibility of iucreasing the performance o£ decantots ay using floculents.

A series of laboratory experiments was performed on cock solutions and the uest floculents uere then tried in a small-scale decantor. It was found tliat a good floculent decreased decantation tine by a factor of 5 - b„ For the determination of decontamination factors a quantity of trace elements were added to the solution. There vs* no difference in the decontamination factor whether floculents were used or not.

USE OF ADSORBANTS IN LIQUID WASTE DISPOSAL: S.A. Adar and «. HorntK. In. connection with radioactive liquid wast* disposal, a scries

of sxpexintots \m* conducted to dettralnc ch* adaorption of individual radioisotopes on various inorganic sorbents, such as allies gel, alumina, varaicullta, titanium phosphate, xlrcooiua phosphate and potssalua cobalt farxocyanlda, U 7 C . S S*r - % b , ionic strengths, wars ussd.

1 U Synthatic solutions c,ontainint tractt Ca, 'TUI and B 5Sr. with varying acidity and at atvaral

Neutral alumina gave the best results for adsorbing cerium, strontium and zirconium-niobium, but the pretence of sodium nitrate drasticclly reduced the distribution coefficient (K-) of strontium, «,§;•, fro* approximately 30,000 Co 300 at 3 H NaNO.. T h * ^n values of ceriua and zirconium-niobium ware not affected by the sodium nitrate. Si l ica gel alto £ » * good results for ziKConiim-niohium, but tb* adsorption v*& vary slow, particularly at low pll, improving at pH 7 though s t i l l not becoming as rapid aa vith alumina.

The K-j of caesium on potassium cobalt f errocyanide and on titanium phosphate was of the order of 10 , the former proving efficient above pH 4, while the lat ter was effective below pH 2. both exchangers are affected by the presence of sodium nitrate, but the KJJ i s nevertheless s t i l l in, the range 1,000 - 3,000 with 1 M Ha)»3.

Kone of the Materials tested shoved any appreciable adsorption of ruthenium.

INCORPORATION OF LOW LEVEL RADIOACTIVE WASTE CONCENTRATES IN CONCRETE MIXTURES: S. Aaam.

Th* conversion of liquid radioactive wastes into solid f ora by incorporating the solution in concrete i s widely applied. Research was done on tiie possibil ity of using the nethod for liquid concentrates resulting fro* the evaporation end decantation processes.

A large number of samples were prepared, and the volume strength and lamchability of th* most important isotopes - 1 0 6 + 1 0 3 R u f

1 3 7 C e , 144 90 239 "*Ce, ' v s r , v and *Pu - vera determined. From tha results the optimal mixture of cement, liquid and additive was found. Finely S*oW«i laatoalta powder turned out to be the best additive for our type of liquid.

The influence of salt concentration and tar coating on tha laacaabillty of the isotopes was also determined. To evaluate laachtax is diffaramt eeometrles of cemtat blocks, the diffusion factors for tha moat Important isotopes - " 7 C s , 10*Ilu, Sr - were found. Preli-mimary work fees aov progressed to a stage where practical application ia feasible.

NUCLEAR SAFETY

Research in the field o£ Nuclear Safety emphasized various aspects of environmental pollution. Improved and simplified methods were developed for estimating the dispersion of pollutants in Che atmosphere, and the confidence in meteorological data as veil as the importance of deposition of pollutants were evaluated. These studies contribute to the knowledge required for evaluating the dispersion of both radioactive material and of conventional pollutants.

A feasibility study of inland or underground siting of nuclear reactors in Israel was continued, taking into consideration the scarcity of on-shore sites far enough from populated centers. Legal procedures were concluded for the allocation of three on-shore sites for future single and dual-purpose nuclear reactors. Both exclusion and low-population zones were allocated.

A study of the additivity of effects of external and internal irradiation doses was initiated.

The safety of gauges containing radioactive materials *as evaluated and rules for their commercial distribution were drawn up.

A SIMPLE METHOD FOR RAPID ESTIMATION OF DISPERSION: 0. Skibin.

A well known formula relates the dispersion of winii^ozne material in the atmosphere (in the y direction^nomal to the ,r.eau wind direction x ) to the standard deviation of the wind conponent along this direction, o . Some rather complicated formulae are

(2.3) v

given for the probability distr ibution function of the azimuth angle of the wind, Q.

Using certain assumptions, a sirup le relat ion has been developed:

2{G 2 cos 2 0 + C 2

/2n (G2 cos2Q + G 2 sin 20) J

where G , G are the intensities of turbulence in the u' v directions and 0 the angle between the mean and instantai azirauth of the wind. At about 0 = 0 the behaviour of P(C) is Gaussian and P(Q) = — — . Using the system developed by

8-0 /ST G v Asculai , we measure the left hand side of this equation, thus obtaining G , and ki^wing tite mean wind speed u, i;e obtain a .

References: 1. PASQUSLL, F., Atmospheric Diffusion, Van Host rand, 1902 2. F?~.~IEL, F.tT., J. Meteorology _S, 316 (1952) 3. SYOKO, S. and 1ANAKA, !I., J. fle't. Soc. Japan 4£, {JE (1966) it. ASCULAI, E., internal Rep. (1965)

HAZARD EVALUATION AT THE NRCN: D. Skibin and E. Asculai. The routine operation of nuclear installations necessitates

hazard evaluation, techniques for the surrounding areas. Until recently, hazards evaluation at the NRCN 1 ' was based on a rather simplified

(2.3) model of dispersion which utilizes qualitative and simple measurements A new method has now been developed which uses a computer program

(4) (AHAM-2 ) and provides the following informations a) The gamma dose rate and Total Integrated Dose (TID) due to direct gamma radiation from the cloud; this part of the program is adapted from the program of Duncan et al. . b) The gamma dose rate and TID at various heights from deposited radioactivity, c) The dose received through inhalation of polluted air. The program computes the hazard due to an all-inclusive discharge (the Way-Wigner equation) or to 50 discrete chaing, each

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having, a parent and a daughter contribution. The release model used In the construction of the prograst takes into account constant ar variable ra te leakages of radioact ivi ty Into one or two consecutive chambers (e .g . into a room and thence into the en t i re building) before i t i s released Into the atmosphere fro* a point source. The dispersion model uses Sutton's theory* but the program nay use parameters computed from Pasqui l l ' s s t ab i l i t y categories or other measurements of dispersion. In the computation the progran also considers the existence of the ea r th ' s surface, an Inversion layer , deposition (Chamberlain's model) and radiation attenuation during passage from cloud to detector (5 detector positions and 8 times considered are parameters).

AHAN-2 provides accurate r e su l t s in a comparatively short computer time.

References:

1. ROFMAN, A. and ASCULAI, E . , in ternal report (1966), in Hebrew 2. HILSHIER, W.F. and GIFFORD, F.A. ORO-545 (July_.1962) 3. Theoretical Poss ib i l i t i e s and4 Consequences of Major Accidents

in Large Nuclear Power Plants , Wash-740 (1957) 4. SK1BIN, D. and ASCULAI, E. , ANAN-2, Internal report (1969), In Hebrew 5. WNCAN, D.S. et a l . , Atomics International NAA-SR-Merao 4822 <196S)

METEOROLOGICAL PREDICTION FOR AIR POLLUTION EVALUATION- CONFIDENCE IN ANNUAL FREQUENCY DISTRIBUTION OF WINDS IN ISRAEL: G. Ehrlich, H.R, Striem and J. Tadmor.

Ir, the evaluation of trie a i r pollution d is t r ibut ion front a given source, use Is wade of t',\n periodic (e .g. annual) frequency d is t r ibut ions of \ilnC circctions ana velocities. Similarly, hazards evaluations for rclu^ae ol pollutants in accidents arc also based on wind dis t r ibut ion pat terns .

, .A study was in i t i a t ed to estimate the confidence \ .th which the frequency dis t r ibut ion of wind directions, and ve loc i t ies can be predicted froui- previous meteorological measurementu. The measurements taken a t AVticiod port over the past 9 yeurs provided the basic data for t h i s study. Utian annual frequency dis t r ibut ions of wiad direct ion and velocity were couputed unu tuo ocviation from the 9-year jnean frequency was evaluated for each year sej^ratuly.

Provisional result* toe the eight western directions (SSVI-N) show that : the IUQUD deviation.for any meteorological condition defined by wind direction and velocity amounts to 27.5% o f - i t s value in the average frti'jiuincy tiistriL-utiom The prodiction of Mind,direction id more

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^spendable than that of the velocity; the nean yearly directional deviation from the average is about 122. The average mean velocity deviation is about 2bX, the least deviation occurring for Beaufort strength 2.

RELEASE OF POLLUTANTS TO THE ATMOSPHERE FROM POWER PLANTS: ARE MGHEA STACKS ALWAYS DESIRABLE?; J. Tadmor.

The increasing demand for e lec t r ic power has created an acute

problem of envirorwen'talair pollution due to the dispersion of SO.,

fly-ash and hydrocarbons released from power plants . There has bean

a trend to build higher and higher stacks in the belief that an in*

crease in the height of release helps to minimize the coneeo.trati.oTi

of the pollutant at any point in the environment.

ic? id* Oil tone • Cm)

Fig.l Instantaneous centerllne concentration as a function of height of re­lease '(h)' of SO* and distance from source, inversion (t) conditions.

Unit (1 g/i*c) YftltMft. Deposition velocity i 1 cm/ice

In'the present study the concentration of SO- being released from a pouer plant uas confuted as a function of atmospheric goutiness

-216 -

conditions, height of release and distance, witli and without conside­ration of the effect of deposition. I t «as found that wJien considering deposition, an increase in height of release may, within certain l imits , increase the concentration of the pollutant at a specif ic distance.

Figure 1 shows a typical exmaple of an increase in the concentra-tloai of the pollutant at a spac^.ic distance from the source, due to ML imcraase in the height of release. Unit release (1 g/*ec) , a. deposition velocity of 1 ca/sec and inversion (F) atmospheric condi­tions w*xe asstmwd in this example. Under these assumptions, for a 1000 HI* power plant emitting about 4 kg/sac of S©2 released at a height of 200 a, the ground-level concentration at a distance of about 40 ke (region of ms*-fmr concentration) -would be about 3 mg/m <1 ppm by volume). Following a release at 100 m or 50 m, the concentra­tion for the seme conditions would be 0.8 Or 0.3 ppm, respectively. (The lat ter may be considered as acceptable).

The effect of increased concentration of a pollutant due to an increase in the height of release i s especially Important when highly populated centers ate found in the region of increased concentration. Thus i t appears that in designing the height of release of a pollutant, an optimization ttiAy should be made taking Into consideration the c r i t i ­cal distance from the source of release i . e . the distance at which the population uould be most affected, toe velocity of deposition of the different pollutants, the directional frequency of winds and acute and average continuous exposure of the population to a polluted environ­ment.

INLAND SITING OF NUCLEAR POWER REACTORS IN ISRAEL: E. Farhi, H.L. Strfwn and J, Tsdmor.

One of the Important parameters i n choosing' a s i t e for a nuclear power reactor i s the proximity of cooling water needed in rather large quantities for the reactor. For an^open-cycle cooling syaten.the only available vater supply in Israel would be the lledlterranean Sea. i!owever, the shore i s relatively short and nostly populated or reserved for tourist or industrial projects. Therefore, a feas ib i l i ty study of s i t ing nuclear power reactors inland i n Israel was made. For compari­son, closed-cycle cooling towers ' using make-up water provided from undergroind supplies (especially of brackinh water), natural draft cooling towers, as well as the pumping of sea lister to the reaetor s i t e in an open cycle jere considered. Tiie study uas made on nuclear reactor out­puts of 200, 300 and 500 *iKe>

- 217 -

Tlie following assumptions ucre nadc concerning cue cuolin- ^y-tc.-i; in le t -ou t le t temperature difference: G C; oriounc of caLe-u^ -atcr required for cue cooling tov.-cr; 1.5 - 3~5 l i fet ime of cooling jyjte:,; 15 years. Table 1 indicates the preliminary resul ts of Cue couparacivc cost study for a 300 '.Ave nuclear reactor . (Tue cost of an open-cycl«: cooling system for a nuclear reactor located on tlie seasiiore uas ta!.er. as 1002)*

TABLE 1 Comparative cost (.2) of different cooling systecs

Cooling system Capital investnent

Yearly operational cost Kerjacks

Open-cyclej 100 10C P.cactor on shore sea water Open-cycle. GC0 56U Reactor located 10 hs. sea water inland, 50 netcrs above

sea level; sea water pimped through pipes.

Closed-cycle, 280 IS brackish water Natural draft 470 5 cooling tower

A l i t e r a t u r e survey of the ava i lab i l i ty of urackish water (under­ground or surface water) in Is rae l and a feas ib i l i ty study of s i t ing of nuclear reactoTS in the proximity of Che brackish water supplies was also made.

Several s i t e s were suggested as sui table for inland locating of nuclear reactors .

UNDERGROUND LOCATION OP NUCLEAR REACTORS IN ISRAEL: M. Geitheim and J. Tadmor.

The scarci ty of s i t e s In I s rae l for locating nuclear power reactors , stemaing from the str ingent safety requirement l imit ing the population density in the environs,invoices an in te res t in the study of the feas ib i l i ty of locating, reactors underground. Beside the advantage of reducing the exclusion and low population areas in the environ* of the reactor , the underground location, also has aesthet ic and archi tec tura l advantages.

A comparative economic study was made for on-ground and under­ground BWR and PHB. ?«actors of 300 Iflfe output. Consideration vas given to the Additional voluoe required for an underground reactor due to tha reaerva needed for maat ic ipated changes and tunnels. An evaluation was •ad* of tha transport of fission products released fro*

- 2 1 8 -

the m c u i in case of an iccldtac, considering i»th tli* flou du« to a pressure cradient aad to nolecular diffusion*

Preliminary r u u l t s of the study of different variants Indicate t£c follotfinz. The depth of lock overlying the reactor required for retention of the f iss ion products released In aa accident, without considering further safer? systems such as pressure suppression, e t c . , i s about 200 deters. Location of a reactor tnderground under these conditions may oe feasible only in a suitable M i l or mountain. The voluoe to be excavated for the underground reactor, including tunnels, •ay reach about IJOfc of the volume of an oo-grovaA reactor. The canital construction investment for an underground reactor building may reach about 1301 of that of an on-ground prestressed concrete cylindical contaiaseot.

A. study of available s i t e s in Israel which uould be suitable for the underground location of nuclear reactors was tirade.

RADIATION "ACTION LEVELS" FOR DIFFERENT POPULATION GROUPS: J. Tadmor, Y. Ufihitz, O. Utayi, E. Lutsn and A, Ziv.

Emergency reference levels havs "been established in Israsl for evaluating the safety of nuclear installations . A further study on xeferenca "action levels" t;as made in order to reconaend a guide for action to be taken in case of a nuclear accident involving a severe emergency.

Tiie guide spells out imperative, desirable and optional actions to be taV.en in case of an emergency, yet leaves enough latitude to the safety organisation to nakc its a<m decisions according to the severity of accident, population involved and Available eoergency equipment and •cans. The £ulde is based on consideration of different factors,such aa population involved (e.g. radiation uorhars, population at Urge), radiation source (e.g. external or internal) and rate, expected bio­logical affects (e.£. sonatic* genetic), additivity of external and Internal irradiation, reduction In irradiation sustained due to various actions ta^ea, etc.

Table 1 indicate* trte actions to be talccn as a function of irra­diation level and population and Table 2 defined the irradiation levels aa a function of the radiation aource.

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TABLE 1 Irradiation Action levels

Population involved

Action* to be taken Population involved

From 10 tinea background to level A**

Froa level A to 8 Above level r

Emergency team Population ac large Children & pregnant wooea

Optional Desirable Desirable

Desirable Des irable Imperative

Imperative Inpferative Inperative

-J

* Action includes: distribution of emergency safety equipment, decontaoiiiaclon, medication, and keeping the population indoors up to evacuation.

** See Table 2

TABLE 2 Definition p-f Irradiation Level

Irradiation Source

Level A Level B

Irradiation Source

Body burden uCl

Radiation dose*(ren<) caused to the

critical organ after Body

burden uCi

Radiation dose*(re=) caused to the

critical ore&n after Irradiation Source

Body burden uCl 1 year 70 vei rs

Body burden uCi 1 year 70 vears

External Internal, 1 3 1! Internal, Sr

90 Internal, Sr Internal, 1 3 7Cs

O.S 10 2

300

25 25 23 23 25

25 25 53 115 25

8 100 20

75 250 230 230 75

75 250 230 U 5 0

75

* Considered for a one-year old child in the cases of Internal irradia- . tion.

Reference:

1* Guide for Maximum Permissible Kadiation Doses, for the purpose of evaluating the possible hazard from nuclear instal lat ions, Israel Nuclear Hazards Evaluation Comittee, 1964. (mimeo)

ADDITIVITY OF EFFECTS OF EXTERNAL AND INTERNAL IRRADIATION DOSES:

J. Tadnwr.

The maxtaim permissible irnrfUtlon doses GtFD) proposed to date

for different population, groups deal separately with external and

Internal Irradiation, without a quantitative consideration of the ca3e

Of * •iattltacaatll external irradiation of the whole body and internal

Irradiation of different organs.

- 2 2 0 -

Tit* IOtP*1* i«ctMMCnds, in a general way, the suanatioa o£ the dose equivalents contributed by both external and internal aourccs, Ic also urnawnlr that If the vaole body Is eaposed to an external irradiation source resulting In an excess of $ :iFU to chc gonads or to to* rad bone Btarros, no two or woie orcans shall i t exposed at nor* taao, half their respective M?D.

Ifest auger nuclear accident? «ay result in simultaneous external aad Internal irradiation of both the t.hole cedy and specif ic cr i t i ca l organs. thus i t say be expected that an additive effect wi l l be obtained, due to either synergetic effects or to the contribution of the Internal irradiation, sources, concentrated in a specific orjjan, to the trjole fcody dose. I t i s therefore proposed to express t'ue irradia­tion doae to toe different organs as equivalents of vhole body irra­diation, thus aaiing possible the limitation of doses ay an "integrated" uhole body WWITT™ geraisaible dose. Verification as to whether simultaneous external and internal irradiations are i/ithin the penais-sible H a l t s H y then be toade by siraation of the uhole bad" dose and equivalent iihole body doses resulting fron irradiation of the different organs.

For lack of data on the aynergetlc e f fects or quantitative expressions o£ a "suffering index", i t la proposed that the equivalence between.the effects of whole bod;' irradiation and that of specific organs should be "based on radiation-induced cancer and mortality probabilities.

Table 1 Indicates the equivalent vhole body doses based on the auove. Tiie validity of the proposed equivalent whole body doses for high Internal irradiation dote* and for long-lived isotopes la being studied.

TABLE 1 Equivalent whole body doaea

Imdiacad orgm EqullMlVlt whol* body do*.

BhoU body IM& boo* wrrov MlMt.l bOM Thyroid Lungs

1 1

1/6 1/10 for »dult«, 1/3 for c h l l d m

1M

l»f«t«ac«; 1. ICIP Publication 9 - i K o a a u d i t l m of eh. InUmattoa*l CooalMlon

oft Radiologic^ Prot«ctloaK Pargaao* Praas (1966).

INSTRUMENTATION AND METHODS

A new facility which will greatly increase the scope of research -Che MEIRA isotope separator - has reached an advanced stage of construction and is scheduled to go into operation in 1970. Develop=ent of electrostatic analyzers was continued, and a stabilizer for thercal ion beams in mass spectrometry was designed and built. In electronics, the development of digital instrumentation using integrated circuits was continued, and several instruments were designed for autonatic control of experiments and for adaptation of data for computer process­ing. A new detector for simultaneous alpha and beta counting was constructed, and methods for calibrating various sources afid detectors were developed. In vacuum technology, research on the mechanism of sealing was continued.

MEIRA ISOTOPE SEPARATOR: I. Chavet. MJIIKA la a :iish-current separdtor :or -.t.ibU' [sDt.vfa JC ;irc:. •:.:

under construction. T.ie optical dosi^r. Is .li.-iM -it o cair.in^ .ooJ itiiage qual i ty , even for a r t lac iv t ly • ;Ji» jpL-rtur-- v"-^-l rjdiar.i] a~-long emission s l i t , .Vttrl-iucin;j t';« U J U ! uns'.a.^nsi^ J : t t I - J ^ -t a i l s to sane cdxed tliird order terns, t:e ,'ur.i ^c.Ti oco c.^-. J I - .> as to eliminate these terns, ai •.veil JS c;.- u^ual -.e^ond -ord-ir cer. : J : the aperture aberration. In t .^j t calculation- :"i-in Jj-ii^lJ L>t':\';: to the correct order were t-i^on into account in accorda.*.^!; .-it.. t..>. equaLiona of ..'ollnir and i-.ala . ..:>i.ti Cur ver t ica l ) [JCU.-:,-.;, I. not included In the optical re tui r-.- .cnW , jt-in^, unnecessary for a s l i t - type instrument- .\xial ^or vertic.il) croisin^ of ;..e . ja.-. i : i . entry joundary of die field " ^ adopted Li j rJor to rjt'ucc fri:v„-.'-field effects, Co oiuplif/ £.".*.• <VI:<_-JI t''jujtio.^, j.nJ u J11J_ i ' . .7 i r . i : correction of tlte aperture ,i ' ' V ' rraujn .-; - i i -ni-.j, at t';e entry !ou.-.jjr .•itliout a t£ect in & otiier optical properti.— .J^.n,tic s . . ielJ s are provided at Sot:-. boundaries iv. orVr co r.'iacr t i e •.•sti.-r.j Lo:i of t!...-fringe l la lds and to jocur. 1 t:ti_* Jj-.ir^-J . lu-'.i.ir. CUHMLUW...

Tae optical .system i l lu j t r . i t ' . ' in l'i.v. I '.a- i ie folio, in,, specification:;: b.olMucncoiL5 --.a0;-.utlc t i . l i .-it!. ja t- .K' t . ." = "-'' .-.; deflection raoliuj .' = >?5 .-., d^fl-'ctio:: .in^b = 'w°; non.^1 j~.:r. e:tiC angle e" = 2'1«4P°; u'iject Jl.td.ic-? L* - H e ' ..i ; Li a,:e di.tmicv L" = ldW ..in; rat'.iu." of curj.itur-- at j n t r / •*' = 1 "I ..-. an.! at e.^it ••" = -35).1 .nn; expected Ji^er^Lou > = 12 ua for i: = 1 0 J .

Fi^ur^ 2 shova a sc i^uatLc layout of tl.** inr;trur.cnt :it ',out Ceo s t ruc tura l supporcs and ptt^i-tj manifold.

\Z.\?J: i s scheduled to !JO in ^" i r . t ion by r.i!J l n 7 ? .

LJeferanca: 1. .:OLL.:U, H. and i:.:.\LD, ':., .:uci. l.utr. k i^ioda ^ .13 (1765)

c* ® Fig. I

Optical geometry of IKIRA Isotope separator . 1 - In the horizontal or r ad ia l plane, ilota the curved magnetic sh ie lds . 2 - In the v e r t i c i l or axia l "plane" (shown straightened according to the op t i ca l p a t h ) . The

beam 1B crossed a t the effective entry boundary. The z scale has been greatly exaggerated (* 2 ,5 ) .

+-A

> « igtn ff.-Jy.'^V.-i.'JH'H'l.p SECTICH A-fl

Scheme of MEIRA isotope separator. 1) Dource insulator; 2) source chamber; 3,8,10,15,I?,20) intermediate flanges; 4) oource inflBiietf 5) oource valvo; 6) oecontl d i f ferent ia l diaphragm; 7,18) wluevcs? 9,16) experimen­t a l working cliflinfoero j 11,14) inaunutic tiliiclds; 12) de­flect ion magnet (coilu not uliown); 13) deflection cham­ber; 1?) collector vfllvu; 21) colluctor chamber[ 22) cold trap and diffusion pijmp portu.

- 226 -

CYLINDRICAL MIRROR ANALYSER WITH SURFACE ENTRANCE AND EXIT SLOTS. I. NONRELATIVISTJC PART**: H Z S»r-EI.

Recently Karres et alf-Q investigated the electron optical features of the cylindrical analyzer used by Blauth (3) , la which the entrance and exit alots of the analyzer are on the surface rather than on the axia(+) of the inner cylinder of the capacitor. These calculation* have teen repeated la a. sore rigorous way, and the predicted efficacy of die analyser compared with that of others according to a criterion proposed recently* 5 ' , The coapariaon ahowa this analyzer to be superior to a l l others developed so far.

to instrueent of this design has been constructed and teats of

I t s perforaance are under way.

geferenc—:

1. EAR-EL, H.Z., Subaitted for publication to rev. Scl. Insfcr. 2. KAKXAS, M., PESSA, H. and AKSEU, S. , Annales-Acideslaa Sdentianin

Feonicae Series. A. VI. Fhyilca No. 289, 1968 (Helsinki) 3. BLADTtt, E-, Z. Fhys. 147,228, (1957) 4. SAR-EL, H.Z., Rev. Scl . Instr. 38, 1210, (1967) 5. SAR-EL, U.2. , Kav. Scl. Instr. (In preii)

CYLINDRICAL MIRROR ANALYZER WITH SURFACE ENTRANCE AND EXIT SLOTS. I I . RELATIVISTS PART*1*: H.Z. Ssr-EI.

Th* re lat iv is t lc treatsent of the cylindrical mirror analyzer with surface entrance and exit s lots was worked out. As in the case of axial slots< 2 ^, the optical features are not dertroyed by the

LW*waw««Vra*r«»juior«*i M». 1

rt |vrw of a « i t of nrloua « o l g r i « i . Ih« frapaa a n raproducad f n a Kg, 33 of tha votk of B i r d . t t at a l l 3 ) , with th« addition of U n a comapoaUn, to OM crUaarlcal mirror analjraar foe til. caaaa of ax ia l ' 2 ) (9 - 55°; .erf anrfaoa (»„ - tW) . lo ta .

- 227

r e l a t iv i s t i c effect even for u l t r a r e l a t l v l s t i c pa r t i c l e s . A coizp arisen

of tliis device with other double focusing magnetic and e lec t ros ta t ic

analyzers indicates superiority of the present analyzer, as shown in

Fig. 1-

References:

1. SAR-EL, II,Z,, Submitted for publication to Rev. Sci. Ins t r . 2. 5AR-EL, H.Z., Rev. Sci. Ins t r . 39, 533, (1968) 3. BARTLETT, A.A., KISTINEN, R.A. and BRID, R.P., duel. Instr. Meth.

17, 188, (1962)

ION BEAM STABILIZER FOR THERMAL IONIZATION SOURCES OF MASS

SPECTROMETERS*1': H.Z. Sar-El.

Intensity fluctuations of the thermally ionized ion beam in the source of a mass spectrometer limit the accuracy attainable in isotopic deasureraents- Two approaches have ber-n used in the past to overcone

{21 {" this problem, one, suggested by Reutersvard% * and modified by Kendall*'" is based on electronic stabilization oE the ion beam, and the other, followed by Reutersward , Errock ', Milne et al. and by Abies and Riley4 applies control of the filament current.

t .

o

— I (mini—*

Fig. 1 Ion current for the Li peak, when working with the stabiliser

{line a), and with the commercial system only (line b)

Adopting the first approach and making use of Milne's circuit with some nodification, the desired stabilization was achieved. The elec­tronic circuit of the stabilizer is described in the next article. In Fig. 1, line "a" shows the constancy of the Li peak in the mass spectrometer when working with the ion beam stabilizer* The line was recorded during continuous operation for periods of about 8 hours on different days. The stability achieved in this measurement was better

- 2 2 8 -

tmaa 0»25£ (the *11—-nr current b o v m r w i completely unstable, amrfllaHag arouad the averag* working ralu* with an amplitude- of above t 0.5 A). The fractionation effect , which la rather large for lithium, v u precisely measurable in this cast. Unc "b" in Fig. 1 xepraaaats the characteristic variation of tb« i a w maas peak height wmem operating vitfa the commercial power supply.

Jteferaaces:

1. SaX-EL, H.Z., J. S d . Instr. (J. Phys. E), 999 (1969) 2. lEOTEaSHilD, C , Arkiv Eyaik 1, 545 (1950) 3 . KEKDUX, B.K.F., Bcv. Sci . Instr. 29, 851 (195S) 4 . BEUTERSIUXD, C., J , Sci . Instr. 29, 184 (1952) 5. EKSOCK, CA.,Cser'a Conference on Thermal Ionization (Ed. Associated

Electrical Industries, England) p. 43, 1960 6. HTXKE, J .D. , PSYMt, A.tf. and UEITTEH, R-N-, J. Sci. Instr. 39,

237 (1962) 7. ABLES, J.G. and RILET, G.H., J. Sd . Ins tr . (J. Pbys. E.) l t 329

(1968)

A STABILIZED THERMAL ION SOURCE FOR MASS SPECTROMETRY: A. Shami

and M. EyaL

Ibe roaaifrdal ion source for sol id analysis in the HS2 mess spectrometer yields.beam intensit ies that fluctuate in a very irregular •saner* Ey introducing seme modifications to this inatruaent greatly improved stabi l i ty lias been achieved.

The ion source has two aide filaments, which vaporize the sample deposited on thea, and a central filament which Ionizes the sample thermally. The ions are accelerated by the applied f ield towards an electrode with a defining s l i t of 0.1 am width which transmits about 1/5 of the extracted ions for the mass spectrometrxc analysis. The rest of the Ions are collected by the electrode, which i s earthed. In the modified arrangement (see figure), the electrode ia insulated and i t s current i s led to earth through a resistor l>10 S n ) . By ftablllzing the magnitude of tills current a constant ion beam for the mass spectrometric analysis i s obtained. Hie stabilization i s achieved via feedback to the filament current, by applying the voltage drop on the 10 Q resistor to a FBI operational amplifier with variable gain and thence to a magnetic amplifier which cun control the filament current-

T.iIs nict'-iod i s cultable for elements like lithium which ere more readily ionizable than the inpuritica present,'so that stabil ization caa be applied before mass separation. A diocusslon of some of the in i t ia l results obtained with llchiuu chloride has been given by Sar-El' ' .

m*«g«T^

•oV

Fig. 1 Block diagram of stabilized theroal ton source

1. SAR-E1, U.Z., J. Sci. Inscnci. Series 2, 999 fl?5?) (see preceding article)

\SS METER: A. Reich.

An instrument to compute the mass of an isotope eserging Ere* the slot in the collector of the mass separator was developed. The function computed by the mass neter is: n • k B /E, where a is the mass of the isotope, B is the induction of the magnetic field, E Is the accelerating voltage, and K Is a constant. The nagnetic field Is aeasurcd by a Hall probe jiving an output voltage proportional to B. The block diagram of the instrutaent is given in Fig. 1.

SQOJUWG

1 f * ICTWCMC 1 f * 1 f * V » " E 1

wncM f * PffTA*.

I w t n c T t n wncM f * PffTA*.

I w t n c T t n

Fig. 1

Block-dlagraw of the vaaa aattr

PROGRAMMED PULSE GENERATOR: B. RanUfoMci and D. Van*.

A pulse train, controlled by an axtarnal wain pulse* is xsquirtd

in HHR axpcriawnti. An instruaant was designed capable of delivering

up to 16 pulses to 5 aaparata outputs. tt» interval betveen pulses

can be varied fro* 3 iistc to 20 msec. The block disgraa of tha

icatruaant it given in Fig. 1.

Fig, 1 Block diagram of programmed pulse generator

The main component* are a variable clock (3 ysec - ZO msec), four 16-bit shift registers, a 5 He oscillator, and a control and loading unit. The progra* is loaded Into the shift registers. The contents of the last stage of these registers Is decoded. The decoder determines to which output the clock pulse is to be sent. The program Is kept la the registers by feediac. the order just executed back to the input.

MAM GATE J [ | | OUI-t 1 1 1 1 1 1 1 1 1 1 1 OUT - 2 1 1 1 1 1 1 • 1 1 1 1

• I I I 1 1 1 1

UUT-S 1 1 1 1 1 1 1 1 1 1 rig. 2

Typical puis, trsin

If the length of the trsin la l « i than 16 bits, Che fast "*M*t oscillator" shifts the program until the first order Is ready to ba served when the next pulse arrives.

The lastrumeet is built aainly with fast T.T.L. integrated circuits, A typical pules tela la given in fit- 2.

- 231 -

2-30Mc/t, 50kW RMS PULSED NMR TRANSMITTER: A. ShamL

A pulsed transmitter for iCEt experinents was developed, this transmitter Is capable of delivering XF pulses up to 7 kV peak-to-peaJt into a Son load when the pulse irfdth is not soce than 100 usee. The block diagram i s given in Fig. 1.

M 1»Vje U» TO T t t ^

TUBE. PTOTttTCN

>1g. 1 Block diagram of pulsed transmitter

The exciter-transmitter i s a greatly modified Clark transoitxer with a single 4CX300A ceramic tetrode as output tuoe, and a 3 section output tank circuit with the output arranged to catch 30 to 100 ohns. The power amplifier consists of two 4PX 60s tetrodes, as an. untuned claaa C pulsed grid, and a n section output tank circuit,. The output i s arranged here also to match a 30-100 oha load and delivers 7 kV

PP when the frequency i s as high as 25 Mc/aec. The tubes are fully protected against over-current and over-voltage between any electrode pair.

Reference: 1. CLARK, U.G., Rev, Sci, loser. 35, 316 (1964)

DIGITAL STABILIZER AND PULSER; M. Rosmwn.

Stabilisation of the analog channel in gi—• spectroscopy experi­ment! i s a w*ll known problem. The block diagran of a newly designed digital stabllixar and puller la given in Fig. 1. A, reference pulse la inserted into the presaplif i ir input, and placed hefJcen 2 adjacent channals In tha pulsa height analyzer (P.K.A.).

M Kur v l r -

I MCWCUBT wjtsea |

—•oourr * « S A W L K

oCOfMECIMG VOlMGE

J-'iy. 1 Jlod: dtacrari of t.:e d ig i ta l s t ab i l i z e r

CUUWVOLTKC*-

F i S . 3 Jne stage of tiie digital-to-analog converter

- 233

The address of the f i r s t channel contains only zero3 ia the 4 least significant d ig i t s , while the address of the second channel contains only l ' s in these digits (Fig. 2) . This condition wi l l satisfy the relation 2 > H, where M i s the maaiauo possible drift of the reference pulse. The i ' th bi t Is 1 i f the reference peal shifts to the le f t and i t Is zero i f the peak shifts to the right. In this Banner the content of a reversible scaler Is Increased or decreased.

The digital-to-analog converter (DAC) translates the digital error to a suitable correcting voltage which controls the slope of the analog-to-dlgltal converter of the - .E.A. In Fig. 3 the scheme of. one stage of Che DAC i s given. The elano voltage deterolnes the correction, voltage per error b i t . The stabi l izer was designed for use with a Vlctoreen Skip 4096 P.5.A.

HIGH EFFICIENCY INTEGRATED CIRCUIT POWER SUPPLY: M. Rosmann v d M, Buntetn.

This power supply was designed aainly with linear integrated circuits and can be used both as a voltage regulator and as a current regulator. The block diagraa i s given i n Fig. 1.

The input voltage V. i s maintained by a preregulator to ensure 3-4 volt* across the series translator T- , This i s accomplished by switching transistor T- between cut off and saturation, keeping i t s power dissipation to a ninimin.

The V 4 I regulator consists mainly of 2 multi-purpose operational amplifiers (yA741), one for each mod* o£ operation. The specifications of the power-supply are: voltage: 0-30; current: 0-10 Amp; ripple: - 0 . 5 ; l ine regulation: 0.0031; and currant regulation: 0.02Z.

1 s i t "S

-i—r-v } — WW I

1" Ln^n

Kg. 1 Block diign* °f eh. pw«r au>*lr

DIGITAL INTEGRATED CIRCUIT TESTER: J. rwienm. A itopic Ulgital Iate;rated Circuit Tester lias been developed

and builc. It coublnes reasonable cose with ease of operation.

The tester is able to perform static and dynamic tests on Ai;ifcal Integrated circuits working with supply voltages of S or 127, all the necessary voltages and testing pulses are supplied by the tester* It la also possible to connect testing pulses from an external source.

During the development of the tester, emphasis was put on ease of operation. Iz can be operated by relatively untrained personnel after about 5 ninutes training- The display is of a go - no go type and consists of an. incandescent laop in the panel of the tester..

The tests are performed by connecting voltages Co cliosen Inputs and testing the outputs. The adaptation of the tester to different types of I.C.'s is ciade by means of Inserting a multipoint plug into 4 special socket la the tester. The plug* are prewired to suit the circuit requirements of the I.C.'s and a special plug Is available for every type of I.C.

MOSS8AUER ELECTROMECHANICAL DRIVE USING AN LVsyn: M. Martlli. The apparatus for measuring Moisbauer spectra consists of: an

electromechanical, drive, a source, an abiorber, a detection set-up, sad a pulse height analyser. The electromechanical drive causes a linear relative motion between the source and the absorber. The nest versatile and vldely asad systems consist of a negative-feedback controlled electromechanical drive* The feedback la given by a voltage generated by a velocity sensing device.

rimcTON •UfMTps "73-""I—

JMUIg| llf 1

• lock diagra. of tha Moaabauar drlva

• 2 3 5 •

la the present apparatus (see figures) the velocity seniles device i» a Sanborn Linear Velocity Transducer (LVayn). chosen for Its simplicity and accuracy of aeuuring velocity. The electromechanical system consists of an amplifier, driving a 12" high-cccpliance dual-voice coil woofer, mechanically coupled to the velocity transducer. The coil moves a permanent oagnet (part of the LVsyn) within the LVsyn coil.

,*

TV $>!&€. r*

—i

SAZOO

3JUOO

-0 MO

» <f

<J Tf

<P

n B . 2 Schematic diagraa of the '-'aasbauer drive

Tin imaUtm The amplifier conaiate of:

(1) A pra-anpllfier, the function! of vhicb. a n : a) to ana the fall­back voltage and a reference voltage taken from tbe function

rrator; b) to amplify the error; c) to operate on the amplified error by means of * linear frequency sensitive network, la eucli * way as to aptinize the dynamic response.

(11) A power amplifier.

The LVsyo The LViyti transducer measures linear velocity. It consist*

of two parts; {O a shielded cylindrical coll assembly; lit) a high coercive peroanent Magnet, The relative motion of the magnet and Che coll generates a voltage, the magnitude of which is proportional to tUe linear velocity, and the polarity of which indicates the direction of the notion. The lVaya features extremely rugged construction, ffcere axe no springs, levers, bearing*, or other delicate parts.

Tests of the entire set-up have shown a deviation from linearity Of about 0.152

ti Vbitoge

Permmenf magnet core

aoitKi weriwHq tong» |

Core • dsp toa iwn t

rate

Fig. 3 Scheaatic of LVsyn

Fix- 4 Response of LVeyn

A FLASH PHOTOLYSIS MEASURING SYSTEM: Y. Gshty,

A flash photolysis measuring system has been built to investigate fast chemical processes in solutions,

Light of constant intensity pasaea through the solution to 1>s investigated and contlnuaa to the photomultiplier. The deflection of the oscilloscope electron beaa is proportional to th* Intensity of the light arriving at the photo-cathode,

A strong pulse of light la generated by the faat discharge of a capacitor c through the discharge tube. This induces a shift in the equilibrium* constant of the solution end changes the molecular concentration. Thus the transparency of the solution changes, and ia detected by the photomuitipHer. The dynamic properties of chemical

- 117 -

processes can be investigated by this technique.

The system consists of the following (Fig. 1):

a) A light source of fixed intensity. The stability is achieved by connection of a xenon lamp to a stabilized power supply.

b) An optical bench.

c) A Faraday cage which includes the storage capacitor C , the discharge tube, the switching device for the discharge tube, and the H.T. power supply. In order to achieve short light pulses* low inductance capacitors were chosen- All connections were cade the shortest possible. For the switch we used a triggered spark gap cade by E.C, & C. The pulse length achieved was 10 usee with an energy

which was built in o1

tungsten electrodes. laboratory, consists of a quartz tube ith

A detector assembly consisting of a photomultiplier, lochromator and oscilloscope.

2 LENS

1 raftaCur « G E

i 1 £

LA

6 W

2 LENS

1 1 i X

11 SuPPL*

i 1 £

E*0TCW. tT fVEO LA

6 LA

6 J u 1 1 - l — l T * SOLUTION

10 B£ tNVE5T«MIE

J u 1 1 T * SOLUTION 10 B£ tNVE5T«MIE

J u 1 1

O CSCttOSCCE

REG PWH SUPPLT

T * SOLUTION 10 B£ tNVE5T«MIE

J u 1 1

O CSCttOSCCE

Schematic diagram of flash photolysis aeasuring aysten

TEMPERATURE PROGRAMMERS: Y. Gabay.

Programmers have been designed to control Automatically the

temperature of crystal growing furnacts (Figs. 1 and 2) .

The programmer works by connection of a reference voltage which

changes with time, In series with a thermocouple inside tha furnace.

The tenoerature controller neasures Vp + V-JC and trial to keep the

sura constant. A change In Vp changes V?c» *nd so changes tha

temperature in the furnace. We change the Vp by a stepping-eotar

which advances step-by-step according to voltage pulses applied to

i t . The atcpplng-aotor turns a •ultiturn pottntlonetar which i s

connected to a reference voltage supply. The heating rate i s deter­mined by the pulse rate and the reference voltage level*

«! , . •¥ , TO COHTROU-ER

n;, -Fig. 1

Connection of a tenperature programmer to a controller.

Several models of programmers have been bui l t , which provide the following kinds of programs: a) gradual heating and/or cooling foe processes continuing up to 100 hours; b) automatic change of teaoerature rise rate when the temperature reaches a preset point; c) a tenperature program -up to 300 hours according to Fig. 3.

The progran la Fig. 3 includes: a) heating at a preset constant rate; b) isotherm at a given temperature during the desired time; c) cooling at another preset rate. Transfer from regions I to II i s made according to a comparison of the output voltage from the thermo­couple Measuring the programed temperature, with a preset voltage level. Transfer fron II to III i s made by a digital clock built into the programmer.

j *. tcuKir t V f i n

| LOCK CKUTS • A T ) STEPPNG MOTOR

Fig. 2 Schematic diagraa of a temperature controller

Fig. 3 A. tenperature prograa

LEVEL DETECTOR FQR LIQUID NITROGEN; Y. Gabay.

A system has been designed and buil t to indicate the level of liquid nitrogen in a tank (see figure).

The detector i s a thermistor connected as one branch of a bridge which feeds an operational amplifier. When the thermistor ccraes into contact with the l iquid, the resistance r ises (due to cooling). The bridge provides a voltage which, after amplification, i s used to indicate the level of the l iquid. The system incorporates two detectors, an upper and a lower, in order to give information on the extreme s t a t e s : "ful l" and "empty".

Fig. 1

Level detector for liquid nitrogen.

INEXPENSIVE, ACCURATE TEMPERATURE CONTROL FOR BATHS: S. Amdur. The accuracy of Measuring tuny physico-chemical var iables ,

anong then differences of several microns in vapor pressure between solvent end solution, was found to be strongly dependent on tempera-t u r . & ' .

Modern commercial instruments for accurate temperature control baaed on thermistors or quartz crystals are available, but s t i l l re la t ively expensive. The main problem in fine temperature control with'on-off heating eyjtems i s the overheating, i . e . the addition of extra heat to' the bath by the heating element which remains hot af ter the current l a turned off. Thia problem i s overcome in sou* of the

commercial instruments by a method of steady differential heatirifc. The coupling of a toluene*-mercury thermoregulatar with an infrared

- 240 -

IMJC Nvrct saabl** oae to overcome ch« overshooting problem of an •m-eff system.

A method trued CM the coupling of the conventional toluene-mercary thcraoregulator **•" * simple Infrared beat lamp waa found to coatrol the teaperatore to ±0.001 C at room teaperature in 5-200 l i t e r hatha. The coupling has the asm* effect as the l ess desirible method of coiling a low voltage bare heating element arouad the glass bulb of a toluene-mcrcvry themoregulator. Tha toluene has an Infrared absorption peak at about 1.7u where water does not absorb. Thus the theraoregulator Is heated sl ightly aore than the water in the bath and the heating stops a l i t t l e before the bath reaches the required teaperature. Overheating then brings the oath to required temperature.

Inference: 1. AMXm, S. , J. Phys. Chen. 73, 1163 (1969)

AN EFFICIENCY INDEPENDENT METHOD IN GAMMA RAY SPECTROSCOPY*1': G. Adam and J . Kstrid.

Ijeacuremeut of the sua peak activity for cascade emitters i s used as an internal coincidence in order to evaluate the absolute activity of such sources.

jteference; 1. ADAM, C. end XATf.IEL, J . , health Phys. 16, 793 (1969) and 17,

M7 (1909)

A NOTE ON THE WALFORDDOUST METHOD FOR RAPID CALIBRATION OF GERMANIUM SPECTROMETERS^: A. Dotev, G. Adam and J. Katritl.

It Is noted that lii the Malford-Douat method some corrections should be made for the efficiencies determined from photons originating froa caicada transitions.

inference: 1, DOLEV, A., ADAM, C. and KATRIEL, J . , J. Kiel. Initrua. Methods 68,

176 (1969) *~

ABSOLUTE CALIBRATION OF BETA-GAMMA SOURCES^: G. Adam and J. KatrJd. Abwolutc calibration of beta-gonna sources la performed by the

use of an aI>sorter and coincidence circuitry. The relevant equations are developed and solved.

•Kefcrance: U ADA;;, C. and KATKIEL, J., Health Piiye. 17, 731 (1969)

A SEMICONDUCTOR SANDWICH DETECTOR FOR THE SIMULTANEOUS AND INDEPENDENT COUNTING OF MIXED ALPHA-BETA SAMPLES: J. Liran.

In ifealth Physics applications, there is a frequent need for counting samples uhich contain a nixture of alplia- and beta-e=ttter3. In suoi cases, one i s interested in getting the individual alpha and beta count rates with Bin! cam interference and In r-dnlsnn ttae.

Hie usual routine Is to count ta.e sample v±zh tvo different detectors P or with the sane detector &ut with a different vorJcin- yeiat for alpha and beta {e .g . a gas-proportional counter with different settings of the high voltage aad./or the dlscridnatioa l e v e l ) . In. bath methods, two aeasureaents are required for each saaple, and there is always a certain contribution of the beta to the alpha count.

Another method percits the simultaneous counting of alpha and beta, by using a single detector (proportional or semiconductor) and two energy channels, thus separating alpha from beta according to the difference In pulse heights. In the case of a relatively thick sa=?Je (which i s the noroal case in Health Physics), there i s a contribution fron the low-energy ta l l of the alpha spectrum, to the beta channel. Moreover, this contribution varies by a lar&e factor from sample to sample, depending upon the type and thickness. Thus there Is no constant correction factor.

In the present work, ve tried to solve the problem by using a sandwich send, conduct or detector,with one detector strying a* ait alpha detector at the sane tine as « ueta window, and tin other as a beta deteccot*

The alpha detector i s a -wty thin (75u) totally depleted Si detector, which can stop alpha particles up to an enersy of 11 HtV. I t i s also cht" enough to satve as a window foe bate partlclea. The minimum energy with vhlch a beta particle can penetrate the window and s t i l l be counted by the beta detector la about 200 KeV.

The beta datector Is a lithium-drifted SI detector, with a 2 urn deep depletion layer. Thus i t permits eff icient detectlcm of beta particles up to an energy of about 3 .EeV. 7U* affective area of the sandwich detector i s 200 am . The sandwich i s enclosed In a 5 est thick cylindrical laad block as part of an automatic sample changer*

- 2 4 2

Th* electronics cotairise a bias simply for tlie da t i c tors, two low-noise charge-sensitive FLT preamplifiers, a double scaler with built- in discriminators, an electronic timer and a controller for the automatic sasple ciianger.

Ihc alpl*a discxlnlnator i s set to reduce the beta contribution to zero. Hie beta discriminator i s set to cut out the background noise of the detector (^33 *ev),

Under these conditions we achieved a simultaneous independent counties of alpha and beta with a 2* efficiency of 27A for alphas (for a tiiin source), and a 2T efficiency of 312 foe Sr-90 betas and 29* for Ct-36 betas.

PUMP FOR CORROSIVE GASES: S. YosHon.

A pomp for the compression and evacuation of gas used for the transmission of add solutions was designed. I t consists of a vane-type pump, and a •onoblock unit. The. notor i s specially designed for transmission of corrosive gases.

The pump i s made of a stator of stainless s teel or Monel, according to the atmosphere used, and the rotor and vanes are graphite or carbon.

Pig. 1 Design of pump for corrosive gssei

Kefereqcas; 1. Crocker * King, Piping Handbook, 5th Edition, McGraw-Hill, H.Y.

(1967). 2. Corrosion Tables, AVESTA, Sweden

OXIDE FURNACE: S. Yoiifon

An oxide furnace for the pxeparation of uranlua oxitl: n a v i e s was b u i l t . The furnace temperature can reach 1600 C under bydrcjEs atmosphere, with a homogeneity throughout the furnace of +5 C, The heating system Is of oolybdenun on as al ioinlua pipe, an£ the radiation shield I s also of aolybdeaua.

• t u t B S S S * X S

/*

Fig. I Design of oxlda furnsca

The advantages of this furnace are that l u construction permits aside ettsmantliaCi *«* heating element la rclatlvaly inexptnelve, and the fit*. of cooling Is alow thus preventing cracking off samples after sintering:..

•efe; 1* EOOL, Handbook o£ Materials and Technique* for Vacuum Device*

Befmhold Publishing Co., 1967. 2. KEKK. D.Q., Process lie at Transfer, HcGrau-Ulll.

SIALOGRAPHY Of FftEttURE SEALS: A. Both.

The equation* describing the sealing mechanlsr under molecular flow * were extended to higher pressures wtu.re intermediate and viscous flow occurs. It was fouid that while the specific leak rste under molecular flow i s expressed by

the flow in viscous regime can be expressed by:

2K'

where p depends on the nature of the gas, and has the dimensions of velocity. C 0 - 205 (£/aec)(aa/ca 3) for He, sad p - 77 for o o air «t room temperature*) K i s a constant depending both on the nature of the gas and the kind of surface roughness. For He , K - 0.19/ /2/icga . A i s the peak-to-valley height of the surface roughness (em), K is the tightening Index* , P. and P are the pressures on both sides of the seal (toi;r). L ^ and L - v are expressed in (torr £/see)(mm/ea).

DM transition from molecular to viscous flow occurs as shown In Fig. 1. Equations expressing the value of h were derived, Based on Knudsen's equation.

The position of the transition region was found to be charscte-rized by the intersection of the l ines corresponding, to L and 1 . This point of intersection, for P - 0 t corresponds to

1 . n * 3 , *** • * *K 2 \ -X. 1

Using these equations the master grsph shown In Pig. 1 may be constructed.

10° 10' 10* 0 ' 0 ' O' ro*

IO1 -4 *3a

1 1 I I t ^u. x° -yp -^p s^p-. Hgfr^m

.0° ^ ^ A W N , 7 $ > v V \ \ \ \ V ,?v

10"' - -ftj. 5S§P^N\\ i/,$' -io"2 ^ ^^v^TS^v \

S^O^F^^^V*- \"^ I ra 3

Si : X ^ £ ^ $ \ \ */

i»- : N \ \ y / _

a ~- io- ! ^x\>yvy\ -S / X§o||v

I 0 6 y • C ^ V ^ V 5 ^ _ . 0 / s^^V^o^v "

-T »JP> / ' - Ji/£- / \ x^^^^ -^ * , *••>$ IO"9

/<&* \ \ -9 W 10

- 1 < 1 1 1 1 , | , , , ,~ Pt (Gtm)

Fig. 1 Master chart for calculating the specific leak rate

when pressurizing the seal

The intersection point L in each case gives the corresponding A

value and -7— (or K) value. The aaster graph not only perolts prediction of the leak race when a seal i s pressurized, but also determination of the in i t ia l surface roughness A , as well as the tightening index K of a seal , i f i t s L vs P. graph i s recorded.

References: 1 . ROTH, A. and AHILANI, A . , i n ZA-1033 (1965) 2. R0TU, A., Saaloaetry and Sealograpny, l a Ptoc. 3rd Internet. Conf.

on Fluid Staling, Ctabridgt, 1967

A CONSISTENT UNIT FOR THE SPECIFIC LEAK RATE OF SEALS: A. Roth.

A consistent unit for expressing the specific leak rate of seals was derived «• a result of further invealigations carried out using the Method of laalography a.2) This unit i s expressad by:

A . f i ^ t . s j / i i i , - *

when . * ^ _.** i -», —* * corr l i t e r am (a«al width) t . la * . .pacif ic l « k rate, in. — — . m j , ( a l I , n t t ; )

C s t t tbc specif ic conductance. In " , ^ e ' . ^ *

Af la tn* preesur* difference aexoas the aeal(tarc),

r and r, axe the oatalrfe end Inside cadil of Che aeal,

respectively ( o ) >

C la cfc* total w>«aartanr< of the seal ( l l t ec / eec ) ,

T la the abeo>l»te taaperatvre of the gas,

M la the noleewlar weight of the taa, A la die pcak-to-Talley height of the surface roughness of the

ecaliag serf ace (ca)»

Specific conductance CB and specific leak rate L, , aa J functioa of aurfact roughnasi A

- 247 -

Thus the specific leak, rare L „ or the specific conductance C . La directly related to Che Init ial surface roughness A by the sicple

2 relation Cfl - p A , where P Is a factor which depends ca the u t « ? of the gas as well as on the tightening history of the seal .

Values of C and L as a function, of surface toughness £o_ various gases and tightening indexes are shown on Fig. 1. The surface roughness resulting fron various types of Machining * shows that perfectly mating surfaces having the best surface finish cannot achieve specific conductances lower than 2 * 10 {C./sec)(m/e&). Lever specific leak rates require tightening farces which are quite conside­rable ( < > 3) i f very low so-called "zero leakage" Is to be achieved.

References: 1. ROTH, A., Sealonetry az.d Sialography, in Proc. of 3rd Intena­

tional Conf. on Fluid Sealing, Cambridge, 1967 2. ROra, A. and ISBAJt, A., in U-1128, p.209-212 (1968) 3. G003ICU, 3 . , HASA-N67-35575/1967 4. GITZENDANNER, L.G. and RATHBUH, F.O., Jr . , General Electric

65 GL-73 (1965)

THE LEAK RATE VS. TIGHTENING FORCE IN METALLIC O-RIMGS: A. tnbar.

In research conducted on gasket seals , the leak rate vs . tightening force relation for a gasket with rectangular cross section was found to be

/5's.,— ^ . - f f ' s u) sealed gas gasket tightening

geometry

where L Is the leak rate ( l / s ec ) , T la the absolute teaptrature (*K) tt i s the molecular weight of the sealed gas, up it the pressure differential across the aaal (torr) k

A i s the roughness peak-to-valley height of the flange (CM), r i t tha average radius of the seal (ca), b i s the width of the seal (a t ) , P Is the nominal tighttning pressure (kg/ca ) ,

2 R Is the sealing factor (kg/ca ) .

I t ia possible to develop the following leak rats vs. tightening pressure relation for gasket* with circular cross section (0-rioae) using Eq.( l) .

- 248 -

I - [l.93 . 10* / I ip £ &• . - 3 r - ' R ] K | 1 (2>

vbar* d i s the diaaeter of the cross section of the gasket (cm), K I s tbc shape factor, F I s the pressure on die gasket according to ?m *• F/2ixd, 7 i s th* tightening force (kg).

The value* of the shape factor K calculated for lead gaskets CR - 200 kg/cm and yield strength 0 - 1 5 0 leg/cm ) are given in Fig. 1 as a function of tightening force F , and deformation ratio a . l a Fig. 1, a - h/d uhere h i s the height of the pressed gasket, and o* - la I ft .

10 OS p i &7 0 * 09 CM

Fig. 1 - Shape factor of actal 0-rlngs,

The calculated values of K were verified experimentally using a phototcehnique. The variations in the shape of the gasket during the defonaetloQ are Bivtn in* Fig, 2.

- 249 -

K g . 2 - Deformation of 0-ring gaakata.

References; 1. ROTH, A*, and AKELAitl, (lobar). A*, In Proc. 3rd Vacuus Congress

Vol. I I , Perg«B«jn Press, Oxford, 1966 2. ROTH, A., Vacuum. 16 (3) , 113 (1966} 3. ROTH, A. and IHBAR, A., ASTM J. o€ Materials 1 (2) 567 (3367) 4. BOTH, A., In : 3rd International Conference on Fluid Staling,

Cartridge, England, April 1967 <p»per C 2) 5. ROTH, A. and INBAR, A., Vacuism 17, 5, (1967) 6. ROTH, A. and IHBAK, A. in : 4th I n t . Vacuus Congress Manchester,

April 1968

PRODUCTION OF RADIOISOTOPES AND LABELLED COMPOUNDS.

The use of radioisotopes in Israel, irt Che fields of d Lagr.-js: :.-dedicine, medical therapy and research, agriculture, biology. phvsLcjl chemistry, nuclear chemistry and physics, pharmaceuticals ecc. is

increasing steadily. A significant advance was cade last vear in radiochemical production, with the addition of ajiiv new labelled compounds to our catalog of available products.

A new tritium laboratory was put into operation and is concen­trating on the labelling of aaino acids and steroids. The amino acids (about 12 items} are usually specifically labelled, but general anc random labelling are also carried out. Nucleosides* nucleotides ans bases (pyrimidines, purines) are about to go into production. The production of labelled steroids has started with hydrocort isorte, androstene, and adrenostcronet and preparation for the labelling of about ten other steroids are under way. Labelled T-acetic anhydride is also a regular product. The methods used are similar to chose of other producers.

A carbon-14 laboratory Is under construction and is due to be completed early In 1970.

Hew labelled compounds containing r-131 and 1-125, e.g. the hinnones HCG and HGH, are being produced. The labelling of FSH is under study. These hormones were produced with the help of the Endocrinology Department of Tel Hashomer Hospital. The labelling of triiodothyronine and triiodothyronine was also studied and these products will shortly be available.

Other products in the development stage include high specific activity Zn-69m, which is separated from irradiated zinc phthalociamine and prepared in a form suitable for medical use, and improved isoropie X-ray sources. The most commonly used X-ray sources today are based on the rather short-lived Tm-370 (T . - 130 days). Preliminary results show that Eu-155, produced by beta decay following the (n,y) reaction on 5m-154, is a promising competitor for Tm-170.

ISO TOPIC C O M P O S I T I O N Oh IUL>h\t 1JI SlH.J ! !> > V A titikol* ,!iid a LuiiL-.itL'lil'

Iodine-131, produced by irradiation of

In the case of horoone labelling, approximately 10 zoLes of

protein are labelled by *>• 1 nC of 1-131. Since the introduction o£

iodine a tons into the protein nolecule oust be U n i t e d in order to

avoid affecting the biological and irmunochenical properties, the

presence of inactive iodine should be taken into consideration.

Making sone approximations in the light of the cross sections

and half-lives of all the reactions Involved, and assuming an irradia­

tion time (t.) longer than 2 days, and the tine interval between

irradiation and processing (t_) nore than 6 h, the following equation

is obtained:

Inactive iodine Active iodine 88(1 - e""^!) e"" 3 C 2

131, where X] refers to Te, \j refers to

stable. This ratio is shown in Fig.l as a function of the period of

irradiation, for two values of the tine between the separation process

and tne termination of the irradiation.

30 Ooyi of irradiation

Fig. 1 180topic ratio as a function of irradiation tine, for separation laaedlately after irradiation (t? - 01 and after a lapse of two days <t, - 2)

-254 «

•sps rtaa experlmeaeel • u j u r « M t i , uslog a specific Iodine electr*4e, arc l a H T M H K with the value* calculated. Thus for W H O M labelllmg cara should ba taken to use solution* with a favwraal* ratio of active to Inactive iodine. Wferamee: 1. LZTT, A., CVIOK. I . , ZSHK0L, A. and MMDfFELb, 8 . , presented at the

"Horksfcop om Coaadotromlnes", Vista B e n o u , Kexico

SEPARATION OF CARRIER-FREE PHOSPHORUS-32 FROM IRRADIATED ELEMENTARY SULPHUR BY THERMJC OXJDATJOftl: J. Kaner, E. Hoter and R. Gvion.

Heoy procedures for preparing carrier-free ?-32 have been described In (be literature. Several diffusion methods o£ separation have been investigated with a view to obtaining high specific ac t iv i t i e s . In so»e •*nsrarw^? these methods f a i l because the irradiation of sulphur changes i t s physical form doe to variations in the Irradiation, conditions (e.g. temperature).

The procedure presented here i s based on thermic oxidation of the irradiated sulphur. The process i s quick and staple, permitting large quantities of material to be treated and yielding very high specific act iv i t ies .

The irradiated sulphur (spec, pure) Is placed in a quartz f i t . (a in Pig. 1) which i s introduced into a furnace. The sulphur la heated to 430*C end vaporizes to the upper part of the flask, where i t i s further heated by a quartz ring heater (B In Fig. 1) and oxi­dized by air . The sulphur dioxide formed i s absorbed by caustic scrubbers. The scrubbed gases are dried by a liquid nitrogen trip before passing to a charcoal f i l t er and suction pump. The P-32, as phosphate, remains as a residue l a the flask. I t i s extracted with 50 ml of 0.05 molar hydrochloric acid (reflux for 1-2 hours). After cooling, the solution i s f i ltered end concentrated by d is t i l la t ion . A total time of 6 hours la required to extract aore than 95% of the P-32 frcm 20 g of irradiated sulphur.

The product obtained i s of high purity. No gamma activity was detected In any sample, and the gross tefa activity decay curves (e.g. Fig. 2) indicated no other beta activity except P-32. Radio­chemical purity was determined chromatographlcslly and the final product was aore than 991 orthophosphate.

Compared with the usual production processes, auch «* water leaching and dry d is t i l la t ion , the modified procedure described above

- W -

has the following advantages; A ) the process Im "cle.12". aa za sal-lJ radioactive sulphur la recovered; b) the heatl % re -jlt e-enea are reduced as solid sulphur does not have Co be distilled; c) etc col-/ radioactive wastes ate the scrubber solutions which are easily evacuated; d) the riak of coataaioation of the P-32 by radioactive sulphur is very saall.

Arrangement for separating pho=2horua-32 froa irradiated sulphur

>*L-I 1—ii I 1 I 1 1_ ' 0 10 20 30 40

Days

Fig. 2 Beta decay curve of phosphorus-,32

FACT METHOO FOH SEPARATION OF FLUORINE-18; S. A b m N t i n and J. Trump*-.

Fluorime-lA Is used in medical diagnostics for bone tunour Production i s based on the successive reactions Li fa ,a)t

followed by 0 I 6 ( t , n ) F 1 8 . The target i s usually U , C O . ( 1 ) and (Z)-processinc i s generally by chromatographic separation on alumina. .

The product obtained fa * mixture of F ami fluoroalualnate complex, trtticm i s separated by d i s t i l l a t i o n " * . Kb data are given i n the l iterature on the radiochemical purity of produce*

A face Method was developed for separation of F-18 f ioa irradiated Li.CC,. The produce i s F-18 as luoride Inn. carrier free, in a neutral, isotonic and s t e r i l e solution of IJaCl + Ka-SO,.

Double-vailed s i l i c a ampoules ,vith 2 g of natural 1&JB>$ as a thin layer (•<• 1-5 mt} between the wal ls , ate irradiated for 3 h and cooled for 30 min* The ampoules are then crushed and transferred to the d i s t i l l a t ion vessel where the target i s dissolved with 1:1 sulphuric acid. Dis t i l la t ion Is carried out at 140-160°C, with a i r bubbling for 10 adn. A snail aaount of water i s then added, and the act iv i ty passes alnost at once Into tuo successive traps charged with 10 ml of 0.075 3 Zaiiil each., the lat ter solutions are withdrawn, evaporated to dryness, in order to get rid of the tritium, dissolved in pyroxene-free water, and f i l tered by suction* under, s t e r i l e conditions, through a 0.22 \m Mil .ipore f i l t e r .

Cadlomicllcttc purity i» checked by gsmm spectroscopy* Radio-chasdesl purity i s assayed by ascending chromatography on Whatman paper {Ko.3Ml)»uflag a* solvent butanol-methanol-water 1:3:1. Results are cheeked against "cold" T~, developed by spraying with Fe(K03)$ solution followed by KSQT solution (F~: white spot on red background). RF of carrier-free W F ~ - 0.49-0.46 and that of Inactive F~ tended to this value as i t s concentration was lowered.

The following results were obtained: act iv i ty aeparated -4 to 5 »Ci; chemical ylald - 80 to 902; tritium - below permissible doses; other gamma emittera-undotectable,

Beferences1 1. Manual of Kadioisotope Production, IAEA, Vienna 1966, p. 185 2. ibid p. 193 3. ibid p.lM

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PRODUCTION OF YITTERBIUfcM69 OTPA COMPLEX J. Trump** j?rf S AfirZL-Jua

Yb has good characterist ics as a scanning agent, except for £ta relatively long ha l f - l i f e . Agitost t i l ls, die biological aalf-liffe o£ the uTPA chelate i s very short^. Ocvclapxaz of this produce uaa undertaken at the request of Iioiliasan dospital .

Production la based on dissolution of irradiated Vo,0 3 In LCI, evaporation, redlssolutlon in water, addition of DIPA and neutral izat ion. The solution i s passed thxouga a Dcuex-50 cicroeoluan (Sa*).. Up cake and elimination studies of the product in anicals wi l l cow be undertakes by Beilinson Hospital.

Reference: 1. VlAGNER, H.H. e t . a l . Sycp. on Iledical Radioisotope Scintograpfcy

Salzburg, Austria, 1968, paper SH-103/54

METHOD FOR RECOVERING ENRICHED TtN-112 FROM EXHAUSTED lND]UM-113n> GENERATORS: R, Gwion and J. Kaner.

The demand t o t indiust-llBn generators i s increasing in Is rae l because of the wide application of th is isotope in the nedical field-In many cases I t i s used as a substitute for lodlne-131 and teehnetlirs-99 in labelled compounds.

Ittdiw-123n generators depend on the Ion exchange properties of hydrous zirconium oxide crystals* The column I s loaded v i th a solution of enriched tin-112 which has been irradiated to produce t ln-113. the decay of the radioactive tin-113 produces lndium-U3m» which is eluted with di lute HC1.

The effective l i f e of the generator i s about s ix months (cvo tin-113 half Uvea) . A method has been developed for recovering the t in from the •pant columns for reuse. The tin i s eluted with 50 ml of 1 N caustic soda solution, after which i t i t deposited on a copper fo i l cathode by conventional e lec t ro lys is using a platinum anode* The t i n I s obtained a i a b r i l l i a n t adherent film which i s washed and dried. The t in-plated cathode i s used as the target matsrial for further irradiation. The activation of the copper does not Introduce a problem, as a cooling tisje of on* weak rsducas the activity to a negligible value. The tin la redissolved with 4 n HC1 (the copper la practically not dissolved) and ths solution loedtd on a column to produce a new generator, Contamina­tion of copper and zirconium in the aluted lndiiai solutions was not found to be significant,

The signifiesnee of th is process la that i t l a suitable for countries such as Israel which do hot produce enriched tin-112*

INFORMATION EXCHANGE AND RETRIEVAL

An analysis of the results of a literature search conducted for us by Euratom's computerized nuclear documentation system is described, as well as a project for applying audiovisual coraunications techniques to current exchange of infornation acong groups of scientists.

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ANALYSIS OF A LITERATUHE SEAHCH ON Ge-Li DETECTORS CONDUCTED THE EUR ATOM NUCLEAR DOCUMENTATION SYSTEM'1»: S. Weil.

Recently the Euratom Nuclear Documentation System (ENDS)* » which is a computerized information retr ieval system, began accepting bibl io­graphical queries from us in return for feedback Co help in the evaluation of their system. The l a t t e r Is based on the assignment of keywords to the abstracts of papers appearing in the abstract journals. To date 22 retrospective l i te ra ture searches have been prepared for us by ENDS. Ihe queries were in a l l cases formulated by our bibliographer in coordination with the sc ient i s t concerned. The results o£ one of these l i t e ra tu re searches have been analyzed, and the data obtained were used co work out, for the subject in question, a pattern of i t s information sources-

The case analyzed was a bibliography on the subject "GERMANIUM LITHIUM DRIFTED DETECTORS (Jan. 1967 - June 1969). We received 334 abstracts of documents in reply. Of these, 28 were not pertinent to the subject, and an additional 29 trere duplications arising from coverage by different abstract journals. The r e s t , 277 relevant abs t rac ts , were the basis for the analysis.

I t was found that 6 journals carry 652 of the relevant papers published on this subject in journals, and another 11 account for 151, making a to ta l of 80Z of the papers In 17 journals. The rest were scattered in 33 other journals. As regards the abstract journals, 3 cover 852 of the relevant l i t e ra tu re . Another 3 cover an additional 10%,and the others 5Z. A breakdown of the abstracts retrieved according to year showed * considerable lag in the data supplied by ENDS.

The following conclusions were reached. The ENDS system gives a high relevance of re t r ieval (in the case quoted, 277 relevant documents out of 305, or 90%) and has provided a satisfactory, though not exhaustive, answer to Boat of our bibliographical queries. A serious shortcoming of the system i s the time lag, which nay be as much aa 9 months, due part ly to the lag in coverage by the abstract journals which serve as the source £ot ENDS. I t i c thus necessary to supplement the computer output by manual search for the most recant period. This may be count) ently done using'the pattern of information sources (journals and abstract journals) worked out from the retrospective computer search. This pattern i s also a usaful guide in a routine curtent-•wsrsnes* service. Ksfsranca_:_

1. WEIL, S., I s rae l AEG internal report. 2. BXEE, R., Atomvtrtschaft AtomtscHnik ,12, 7, 365 (1967)

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AUDIOVISUAL COMMUNICATION TECHNIQUES IN SCIENTIFIC^ INFORMATION DISSEMINATION: M. Kaye,

A project Is underway to apply the tools of communications technology to the Improvement of sclent'.fie information exchange. The schcae i s based on two p r a i s e s : a) that there i s a need for exchange of current idea* and data between groups whose work i s related, before the publication stage i s reached; b) that the mode of Lu—mli; irfrin preferred by the sc ient i s t i s speech.

The system envisages the pairing of sc ient i f i c groups which are closely interested in each other's work. Paired groups record their group seminars, meetings and discussions on audio (later video) cassette-form tapes, and exchange the cassettes . The cassettes are then played and simultaneously re-recorded on similar cassettes; the recording can be stopped at w i l l and comments interpolated Into the discussion. The re-recerded cassettes are then exchanged, giving each group a recording of i t s own sealnar with discussion which includes the participation of the partner group. A continuous exchange in this way represents a simple system for the exchange of current ideas and comments between pinups at any geographical location at the stage when such communication i s most useful -i . e . , when the experiments are being done. I t i s effectively a. "continuous conference by mail" in a l i ve form la which the tedious writing atep Is avoided. Moreover, i t adds a new dimension by per­mitting group-to-group as well as person-to-person communication.

Experiments to date consisted of recording the seminars of the Geoisotope Croup, under the direction of Prof. Joel Gat, of the Isotopes Department of the ^eiaaan Inst i tute . The f i r s t recordings were designed to evaluate t!i« performance of the equipment, and assess any inhibitory efface of recording <ri fee* discussion. The equipment consisted of TC-100 Cassette Recorders with 90-mInute play cassettes , plus a microphone mixer MX-6W M, equipped with three t - 96 Dynamic Micro­phones, a l l from Sony, Inc.

Preliminary evaluations are aa follows: a) Adequate sound recording can be obtained without shift ing the microphones during recoedlng, and without requiring the speaker to talk directly into a microphone, which might binder the free flow of discuesioa. b) The recording of blackboard notes and s l ides presents

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a problem. However this could bo overcoce in the video cassette systeo. c) With the group tested, discussion seersed free and un­inhibited; the participants did not notice any change in the discussion pattern compared with unrecorded seminars. The liveliness of the discussion seems to be overwhelmingly determined by the stimulating effect of the paper presented.

In the next stage of the experiments, the Interchange and re­cording of the cassettes will be started.

AUTHOR INDEX

A b r a a h k l n , S. 256 , 257

Adam, C. 8 1 , 8 2 , 240

Adar , J . 15

Adar , S .A. 150, 209

Adman, U. 131

Agam, S . 2 0 9 , 210

Aiadjem, A. 131

A l f a s s l , Z . B . 9 0 , 9 1 , 92

Aodur , S . 126 , 239

Amle l , S. 8 7 , 8 8 , 9 0 , 9 i , 9 2 , 9 3 . 9 4 , 9 6 , 9 7 , 9 8 ,

102, 104 , 106

Amir, E, 69

Amlt , A. 59

Amran (Suss raann) , J . 4 2 , 43

A p e l b l a t , A. 136 , 138 , 139 , 142

A r i e , G. 184.

A s c u l a i , E, 2 1 3 ,

A s s i f , 1. 135,

Avlram, 1. 12, 7 9 . 8 0 ,

Avnea r , E. s e e Wiener (Avnear ) E.

Avn i , Ft. 160, 1 6 1 ,

B a e r , H. 8 7 , 8 3 ,

B a r k a l - G o l a n . R, 1 7 5 , 176

B a r n e t c , B. 44

Bar-Noy ( B l r n b a u a ) i T . 47

Bac-Or, A. 6 9 , 7 0 , 72

Bauainger, E, R. 55 Ben-David, C. 20, 23, 24, 28, 29

34, 15 Ben-Hala, A. 207 B.r.ar, H. 197 Mrirtnu*, J. 1S3 Blrnbaua, T,,aee Bar-Noy (Bltnbaw) Blret, x. 16? J l i t t , S. 1C5 SluwnUld, M. 67 Bluaankxantx, Z. 207,208

Boukobza, A. 160

B r a n d a c e t c e r , J . 1 3 5

Braun , c . 93

S r u n s t e l n , H. 50 Bukspan, S . 48 B u r s t e i n , H. 62 ,233

Cabancchlfc, Z. I . 192

C a l d e r o n , H. 193

Chave t , I . 223

Cohen, A. 121 , 1 4 7

C r l s t a l , N. 200

D a r i e l , H.P . . 5 J . 6 6 , 6 "

D a r i e l , M.S. 148, V49

Dav id , J . 142, 1=13

D e g a n l , G. 151

D o l e v , A. 240

D u b r a v s k i , S . 197

Eden. Y. 107

E f r o n , 0 . 51

Es°«y, v. 1 4 B

E h l c n b c x g , B. 96

E h r l l c h , a. 214

b l a e n b e r g , A. 2 0 8

E i a a n b e r g , f. 1 8 i , 1 8 3 , 184

E l -Hanany , U. 64

E n g l a a n , R. 3 9 , 4 0 , 44

E p a c a i u , A. 57

E a h k o l , A. 2 5 3

E y l a n , E. 199

E y n l , M. 2 2 8

E a c a i i l , ». 1 1 6 , 117

F a t h l , I . 216

F a d d a r , A. 116

F a i j a , K. 1 7 1 . 1 9 3 , 197 , 2 0 7 , 208

• U l U U , 1. 92, M, 97 Hakalatala, L. 11 Faa, I . 153, 155 Fraaaal, 1 . 1*7 Trlti, I . 121, 129 Frlaaaaa, C. US Frlaaaaa, Z. 56 FrUJrtch, M. 51

Gab*/. I . 236, 237, 239 'c* l , J, 55, S n U t , Oi. 98 Caxith. A. 199 Gazltk, H. 82, 123, 124, H I Gafaa. T. 68 Galtaals, M. 217 GllaCk, a . US, I K , 187 Glna, H. 127 Cold, 1. 171 Calaaarc, Z. 161 CoUaarf, H. 167 Galaatala, C. 47, 48 C O M , t . 177 GcwkM, S. 52,53 Graaaaaaa, E. 12 Ctlabctg, J. 49, SO Gar, T. 12 Gwaaltch, I . 57 C-rlo«, *. 253, 234, 257

b a a , K. 23, 24 • • • ]«* , Z. 55, 67, 151 aalaaria, 1. 40 m u , t . 1*2 Uanaa, 1. 131 •Mara, I. 12* ••calk, A. ISO, 20* aarovlM, A. I l l , 112, 11* K*rwiU, I . 115 attar, I . 234

U a a d , Y. 77, 7« lobar, A. 24? tiaak, F. CH. 199

Jortaar, J. 39

Katun, R.S. 176, 177, 178, 179, 183 b l w , Z.H. 59, 60 ( i M t , J. 254, 25; l in<: , H. 14, b r p , D. 207,208 t i l E H I , J, 171 (a tr ia l , J. 81, 12, 24D I l U , M. 11,113 Katiir, A. 47 Kara, H. 262 Xadaa, D. 54 Xadaa, 0. 148,149 Kctzinel, Z. 152 Kiawtl, G. 67, 69 Klnrot, A. 146 Klein, F. S. 121 U l s t e r , H. 60,61 Konljabuch, H. 153, 155 Horn, C. 62, 63 Kraur, J . 191 Kiavlatz, J. 200 Kroupp, M. 67

Laak, S. 185 (.caanaka, M, 10 Lavla, G. 121 Leu-la, S. 49 Lav?, A. 114, 233 Xxty, J. 69 Llban, E. 197 U f a h l t i , X. 219 Llran, J. 241 Litaj l , D. 219 U«M, Z. 70 Locker, S. 54

loureneo, A.S. 260 Low, W. 47 Luljltl, E. 195, 219 Umenfeld, B. 253

Makovaky, J. 56, 57, 59, 60 Mantel, H. 104. 106 H»or, H. 20] Marcue, 1. 127, 146 Marolll, H. 231 Mathtaa, H. w> Mazor, E. 168, 169. 170 Hechoulaa, Y. 198 Melanud, H. 56 Michaell, 1. 146 Meyeratein, D. 114, 115, 128, 129 Holeho, «. see Molco, M, Moleo. H. 169. 180, 181 M o n s e l l s c , S. r . 177

Moreh, B . 20 , 2 1 , 2 2 , 2 4 , 2 5 , 26 2 8 , 19 , 3 1 , 32 , 33

Mukamel, D. 52

Kulac . H.A. 115

Sade l -Shl faana , . H. 183

Hahar in , A. 193, 195, 19<

Hahum, J . 45

Haven, J. 146

K t r - E l , X. 96

Sof, a . 28 .32 .33

Boulk, I . 55

Ofar, S. 55

Oltman, B.O, 17)

Oron, H. 96 , 98

O t t o l t r a M , H. 1 H

Padov. , J 125

Padcrvt, R. 171, 176, 178, 179, 180, 181, 18], 208

ParlM». J, 23* Faval, D. 14.35

Pelan, I. 49, 50, 51 Pereloan, A. 20(1 Pinto, H. 55,56 Planner, t. 121 Proulov, 1. 207, 208

Raananl, CU. 199 Rablnovitz, E. 132, 133 Rafaalof f , P.. 100, 106, 130, 144,

145 Rajbenbach. L A . I l l , 112, 113 Hajewski , J . 19 Ra isaan , A. 46 Ravtv, s . 133, 134 Reich , A. 229 Remlgolski , B. 230 R l k l i s . E. 191 , 192, 202 Rlov, J . 177 Ron, E. 59 Ronea, M, 202 Rosen, M. 6 0 , 6 1 , 68 Rosenberg, J. 152 Rosmann, M. 232, 233 R j s s , I . 179, 183 Roth. A. 244. 245 Rochem, T. 54 Roy, A. 147 Ruppin, R. 40 ,42 Ryndzuoaki, H. 72

Sadeh, T. 194 . 198 S a l n a a n , 0 . 2 0 , 21 Saphi i r , D, 3 , 4 , 6 , B Sar- E l , H.z . 226,227 SchacHacr, E. 200 SchachMt, t . 153, iSS S c h l e . i n g e r , 7 . 2 3 , 2 4 , J 4 . 3 : Schmidt, G.H.J. 19? SchoenHld , I . 161 S e j a l , Z. 98 Shachar, 0 . 5 5 , 56

Shahal, 0, 22, 29, 31 Shake*. H. 52. 55, 56, 57, 5B Shale*, J. 69

Shall, A. 228,232 Shaair, J. 48 Shapiro, J. 199 Shashua, J. 152 Shatz, H, 10 Shenberg, c. 102 Shloao. S. 19 Shtacher, G. 198

Shtrlkaan, 3. 52, 53, 56

Silberazn, C. 200, 203

Skibin. D. 213

Soriano, J. 43

Spector, U. 159, 160

Stein, J.A. 197

Steiner, H. 161

Strlea, U.L. 214, 216

Suas, J.T. 46, 47

Susaatan, J. aee Aaran (Suaaaan),

Shapiro, S. 46

Szlchaan, B. 23,34, 35

Tadaor, J. 214, 215, 216, 217, 211 219

Tal, A. 194,

Teekin-Corooeiakl, H. 178

Tandler, Y. 116

Tenenbaua, J, 28, 29

Thleberier, R. 39 Toaer, A. 69 Troaper, J, 256, 257

Vardl, D. 230 Venalla, A. 94 Volfaon, 1. 67 Volkaan, V. 152 Vulcan, V. 51

Wand, V. 21, 28, 29 Well, S. 261 Weiaa, s. 148 Wernick, K. 131 Wiener (Avncar), E. 49,50 Ulernik, H.. 101, 104 Wilaeradorf, H. 129 Wolf, A. 22, 25, 26, 28

Yaron, F. 167 Yaklr, D. 152 Yanlr, E. 55, 127 Yatoa, H. 41 Yellin, £. 96, 100, 106 Yiitah, S. 3, 4, 8, 12, 14 Yosifon, S. 242, 243

Zafrlf, B. 51 Zaalr, D. 62,63 Zangen, M. 123, 141, 142, 143

144, 145, 147 Zauberaan, G, 183 Zlv, A. 219 Zaora, I. 39 Zodkmlca, A. 59, 60