IEEE Transactions on Nuclear Science, Vol. NS-30, No. 2, April 1983 THE DECAY OF Ag- 10 5g Jasbir Singh, MI.L.G arg, Ravinder Kaur, S. S. Sooch, Nirmal Singh and P.N.Trehan Department of Physics, Panjab University, Chandigarh - 160014, India. The level structure of Pd-105 has been studied from the decay of Ag-105g. 'The energ- ies and intensities of 50 panma rays have been precisely measured using a 64.1 c.c. Ge(ji) detector (FWHM =2.1 keV at 1.33 leV)). The gamuma ray singles spectrum measurements confirm the existence of the 158.93, 167.5, 202.17, 216.11, 382.5, 4-86.65, 576.64, 583.01, 844.34, 860.20, 921.23, 929.01 and 1124.90 keV gamma rays in the decay of Ag-105g. How- ever, the 270.5, 564.39, 580.13, 610.0, 64X0.55, 709.8, 768.9 and 796.25 keV weak transitions reported by earlier vworkers could not be obse- rved in the present investigations.Also the Yi-y directional correlation coeff'icients for 7 cascades in Pd-1055 have been measured. Out of these, the 361-(447)-280 and 807-280 keV cascades have been attempted for the first time. From these correlation measurements spin value of 1/2+ has been confirmed for the 673.03 keV level. Also these measurements have been used to deduce the multipole mixing 10* 6 LZJ 105 z z I w ' z 0 100 300 500 700 900 1100 1300 2100 2300 2500 2700 2900 3100 3300 CHANNEL NUMBER ratios of seven transitions in Pd-105. Introduction The level structure of Pd-105 following the decay of Ag-1q5g had been investigated by many workers1l using semiconductor deteo- tors. The latest o these measurements done by Venneulen et a1g indicated 15 new transit- ions in the decay of Ag-105, which were not reported earlier. An inEepenent work of Jackson and Meyer7 reported only 8 of these additional transitions. On the other hand, there were five other transition: which were observed by Jackson and MeygrlS but were not detected by Vermeulen et al The spins and parlties of the first few excited states in Pd-105 are well establish- ed9. However, in case of the 673.03 keV level the spin shovn by Ellis9 (I = 3/2+) is not in agreemAnt wth that deduced by Behar andGra- boskiO on the basis of directional correlat- ion measurements. The multipole mixing ratios of many M CC'. ... At. 4)L o C.. _cX_ 4!C1 1 500 1700 1900 2100 3 500 3700 3900 4100 Fig.I. Gamma ray singles spectrum of Ag-105g. 0018-9499/83/0400-1143$01.00(c 1983 IEEE 1143
Transcript
IEEE Transactions on Nuclear Science, Vol. NS-30, No. 2, April 1983
THE DECAY OF Ag- 105g
Jasbir Singh, MI.L.G arg, Ravinder Kaur, S. S. Sooch, Nirmal Singh and P.N.Trehan
Department of Physics, Panjab University, Chandigarh - 160014, India.
The level structure of Pd-105 has beenstudied from the decay of Ag-105g. 'The energ-ies and intensities of 50 panma rays havebeen precisely measured using a 64.1 c.c.Ge(ji) detector (FWHM =2.1 keV at 1.33 leV)).The gamuma ray singles spectrum measurementsconfirm the existence of the 158.93, 167.5,202.17, 216.11, 382.5, 4-86.65, 576.64, 583.01,844.34, 860.20, 921.23, 929.01 and 1124.90keV gamma rays in the decay of Ag-105g. How-ever, the 270.5, 564.39, 580.13, 610.0, 64X0.55,709.8, 768.9 and 796.25 keV weak transitionsreported by earlier vworkers could not be obse-rved in the present investigations.Also theYi-y directional correlation coeff'icients for7 cascades in Pd-1055 have been measured. Outof these, the 361-(447)-280 and 807-280 keVcascades have been attempted for the firsttime. From these correlation measurementsspin value of 1/2+ has been confirmed for the673.03 keV level. Also these measurementshave been used to deduce the multipole mixing
ratios of seven transitions in Pd-105.Introduction
The level structure of Pd-105 followingthe decay of Ag-1q5g had been investigatedby many workers1l using semiconductor deteo-tors. The latest o these measurements doneby Venneulen et a1g indicated 15 new transit-ions in the decay of Ag-105, which were notreported earlier. An inEepenent work ofJackson and Meyer7 reported only 8 of theseadditional transitions. On the other hand,there were five other transition: which wereobserved by Jackson and MeygrlS but were notdetected by Vermeulen et al
The spins and parlties of the first fewexcited states in Pd-105 are well establish-ed9. However, in case of the 673.03 keV levelthe spin shovn by Ellis9 (I = 3/2+) is not inagreemAnt wth that deduced by Behar andGra-boskiO on the basis of directional correlat-ion measurements.
The multipole mixing ratios of many
MCC'.... At. 4)LoC..
_cX_4!C1
1500 1700 1900 21003 500 3700 3900 4100
Fig.I. Gamma ray singles spectrum of Ag-105g.
0018-9499/83/0400-1143$01.00(c 1983 IEEE
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transitions in Pd-105 had been determinedfrom the ICC measurements by Kawakami andHisatake3. The ICC measurements do not deter-mine the sign of mixing ratio which is help-ful in checking the validity of particularmodel for a nucleus. The sign and magnitudeof mixing ratios are directly determinablefrom the gamma,-gamma directional correlationmeasurements. These measurements in case ofPd-105 had been done only by Babenko et al5.and by Behar and G rabo wski 8. Behar and G rabo-wski used two different Ge(ii) detectors of aplanar and a coaxial type in their set-up.This set-up had a poor time resolution of 70n sec. Also it suffered from poor coincidenceeffi ci ency.
The present work confinms the existenceof 167.5 keV transition reported only byBabenko et al5. In addition, the gamma-gammadirectional correlation results of seven cas-cades in Pd-105 have been reported includingthose of 361-(447)-280 and 807-280 keV casca-des for which correlations have been report-ed only by us.
The directional correlation coefficientshave been further used to deternine the mixi-ng ratios of 7 transitions and to deduce spinof the 673.03 keY level in Pd-105.
Experimenal Arrange.ments and Data Anal
The radioactive sources of Ag-105g wereprepared by irradating Rh-103 foils with 28
MleV a particles beam at TLandem1 acceleratorAERE, Harwell. The irradiated samples werethen placed in perspex hOlders having central
cavity of about 1.5 mm diameter and 1 cm
length. The experiment was cartied out six
weeks after irradiation oL the sample toavoid the detection of short lived activitiesproduced along with the main source.
The singles spectra were taken with 64.1c.c. Ge(Li) detector in conjunction with4096 channel analyser having energy resolut-ion (FWHM) of about 2.1 keV for the 1.332 MeVgamma rays of Co-60. The source strength was
kept low (about 1000 counts per sec) to avoidpile up corrections. The singles spectra weretaken by placing the source at 25 cm. fromthe detector to avoid sumr,.iing effects. Theenergy calibration of the detector was doneby using strong internal peaks of Ag-105gwhose energies are knovn precisely. The singl-es spectra were analysed using computerprogram SAMPO10.
The gamma-gamma directional correlationinvestigations were carried out using 64.1 ccGe(Li) - 7.6 cm X 7.6 cm "aI(Tl) coincidence
set-up having time resolution (2r) of about6 n sec for the gamma-rays of Co-60. Thedetails of equipment and that of data process-ing and analysis are described elsewhereI1102
RDltsscusdsiconThe amma- ra e_eeYand intensity measure-ments:
The weighted average of the results ofenergy and intensity measurements from fivespectra for gamma-rays at different occasionsand for different periods is given in Table I.The half life of the source was followed toensure the genuine peaks of Ag-105g source.
The present wrk confinms the existence ofweak gamma rays of energies 158.93, 202.17,216.11, 576.64, 844.34, 921.23, 929.01 and1124.90 keV which were recently reported byVermeulen et a16. and Jackson and Meyer7. Thepresent measurements also confirm the existen-
Tabl.e I: Energies and Relative Intensities ofVarioous Gamma Rays in the Decay of Ag-105g.
ce of 382.5, 486.65, 583.01 and 860. 20 keVtransitions reported only by Ven:neulen et alband that of 167.5 keV g Tmma ray reported onlyby Babenko et al7. However, the gamma-rays ofenergies Z70.5, 564.39, 580.13, 610.0, 640.5,709.8, 768.9 an; 49b.25 keV reported inDrevious workst( could not be observed inthe present measurements.
TheDrpQiana o:rriatio 1.1ea su re enxtsThe results of directional correlation
measurements on 7 cascades and multipolemixing ratios obtained from these measurementsin Pd-105 are presented in Table II.
The multipole mixing ratio analysis wasdone by assuming pure Ml character of the 64and 331 keV transitions9'3 and pure 1J2 andpure-El characters of 183 and 361 keV transit-ions3,9 respectively. The A( 280) vaLue andthe correl ation coeffi 9ients of the 370-280,393-280, 807-280, 361- (447)-280 cascades(Table II) have been utilised in determining
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Table II:The -V Directional CorrelationCoefficients and Mixing Ratios in Pd- 10 5.
Cascade Correlation Mixi na Ratios(keV) Co effi ci ents
the mixing ratio8 of the 370, 393, 807 and447 keV transitions. Again in these cases,the exact 6-value was selected fr'm the tiomixing ratio values, provided by A22- cqeff-icient, on the basis of ICC measurements5.The pin of he 67 3.0 keVlel
In the decay scheme of Ag-105g proposedby Kawakami and Hisatake3, the tentative spinof the 673.03 keV level was shown to be 1/2+,3/2+ or 5/2+. The directional correlationmeasurements of Behar and Grabowski8 showedthat the spin of this level could only be1/2+. The investigations of Vermeulen et al:6on the basis of 'log ft' values also indicat-ed the spin of thi s level to be 1/2+. However,the latest data corm;ilation of Ellis9 showsthe spin of 673.03 keV level to be 3/2+ onthe basis of its feeding to and from otherlevels in Pd-105. In the present case the A22coefficient of 393-280 keV cascade wasanalysed assuming three spin values of 1/2k,3/2+ and 5/2+ for the 673.03 keV level and inthis process the following values of mixingratios were obtained.For I = 1/2+;6(393)= 0.05 + 0.04 or 6(393)=1.55 + 0.13
For I = 3/2+;6(393)= 1.05 + 0. 24 or 6(393)=1.6 + 0.6
- 0.23 0.3For I = 5/2+;6(393)= -(4.8 +2. )or6(393)=-(0.45 +0.078
Now the ICC measurements3show that the393 keV transition is M1 + -0.55/ B2. Thisvalue of multipole admixture rules out thepossibility of spin of the 673.03 keV levelbeing 3/2+ or 5/2+. Also for I = 1/2+, only6-value consistent with the ICC measurementsis, 6(393)= 0.05 + 0.04. Thus from the pre-sent investigations it is concluded thatI = 1/2+ is the only spin for the 673.03 keVlevel in Pd- 105.
the D.A.E., Govt. of India respectively.
1. W.R.Pierson and K.Rengan : Phys. Rev.159 (1967) 939.
2. J.Rivier and A.Gizon . Compt. Rend 266B(1968) 1161.
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4. V. A. Sergi enko, L. A. Sa anov, V.I. Berno-tas and A.B.Bibichey :Izv. Akad.NaukSSSR, Ser. i 37 ( 1973) 1666.
5. V. V. Babenko, I. i. Vi shnevskii, V.A. Zhel-tonozhskii, V.P.Svyeto and V.V.TrishinIzv. Akad. Nuak SSSR, Ser. Fiz. 41(1977) 91.
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7. S.V.Jackson and R.A.IMIeyer: Privateommunication to Nuclear Data Sheets1979).
8. M.Behar and Z.W.Grabowski : Nucl. Phys.A196 (1972) 412.
9. Y.A.Ellis: Nucl. Data Sheets 27 (1979) 1.10. J.T.Routti and S.G.Prussin : Nucl.
Instrum. and Meth. 72 (1969) 125.11. A.K.Sharma, Ravinder Laur, n..R.Vema,
K.K.Suri and P.N.Treha:i Jl. Phys. Soc.Jpn. 46 (1979) 1057.
12. S.S.Sooch, H.R.Venma, Ravinder Kaur,A.K. Shama Niimal Singh and P N Trehan:Jl. Phys. boc. Japan.49 (.19805 1222.
AcknowleemtT,wo of us (Jasbir Singh and M.IL.Garg)
wish to acknowledge the grant of JuniorResearch Fellowshfps by The C.S.I.R., and
