Radiation Detection
Ken Czerwinski
II Letnia Szkoła Energetyki i Chemii Jądrowej
1
Radiation Detection
Ken Czerwinski
Radiochemistry Program
Department of Chemistry
University of Nevada, Las Vegas
2
Outline
• Properties of detectors
• Types of detectors
• Research example: Hot particle examination in
the environment
CT imaging of hot particles
Gamma evaluation of hot particle
components
• UNLV Radiochemistry program overview
3
Basis of Detection
• Interaction of radiation with matter
• Particle interaction leaves a signal
Signal is manipulated
Amplification
Transfer
• Provides data on detected particle
Intensity
Energy
• Ability to detect particle function of detector
composition
4
Gaseous Ion Collection Method
• Current-Voltage Characteristics electric conductivity of gas
resulting from produced ionization
current first increases with applied voltage
Reaches constant value, saturation current
* direct measure of rate of charged ion production
Ionization chamber
• Pulse amplification ionization chamber may be
connected to AC amplifier for measurements of individual ionization pulses
voltage pulse is proportional to input pulse (linear amplifier)
5
Multiplicative Ion Collection
• Increase of potential changes detector behavior
• Proportional counter
V1 to V2
ratio of pulse heights for different ionizing events independent of applied voltage
• Above V3
pulse height independent of initial ionization
Cannot differentiate particle
Geiger-Mueller counter region
6
Gas detectors
• Gas Multiplication
multiplication factor M depends on wire radius a, cathode radius b, pressure P, and voltage V
• Proportional Counters
proportionality between pulse height and primary ionization requires individual tracking of avalanches produced by primary electrons
pulse shape independent of pulse height
voltage plateau is region where counting rate caused by radiation source is independent of applied voltage
Exact location depends upon setting of discriminator to eliminate pulses below a given size
Pa
ab
VfM ,
/ln
7
Gas Counters
• Geiger-Mueller (GM) Counters
proportional region of counter operation limited at upper voltage end by onset of photoionization
each ionizing event is along entire length of wire
final pulse size becomes independent of primary ionization
quench gas suppresses secondary electron emission
• Counter Backgrounds
GM and proportional counters limited by background counting rates
Can reduce background with:
special shielding
anti-coincidence circuits
* reject counts occurring simultaneously with counts in nearby counters
8
Semiconductor Detectors
• Solid Ion Chambers
Based on semiconductors
Si and Ge
• Principles of Operation
process is lifting of electron from valence band to conduction band
difference between bands is band gap Eg
thermal excitation leads to some conduction
positive hole created in valence band
energy required to produce electron-hole pair always exceeds Eg because some energy goes into coupling electrons to lattice vibrations
9
Solid state detector
• p-n Junction Detectors makes use of
diode structure that incorporates regions with excess negative and positive charge carriers
Applied potential drives detector
silicon detectors widely used for -ray and conversion electron spectroscopy
10
Solid state detectors • Surface barrier detector
very thin dead layer
sensitive to light
photons can increase background
2-4 eV
* Sufficient for electron hole pairs
vacuum enclosure prevents light
interaction
detector is sensitive to damage from vapor
exposure
usually n‐type crystals
a positive voltage to be applied
• Ion implanted detector
ion implantation used to produced
semiconductor
Ions of P or B
well defined range in material
concentration profile of dopant controlled
Annealing after implantation
More stable and durable than surface
barrier detector
11
Solid state detectors
• Passivated Planar Detectors
thin layer inside windows is converted to p-type boron ion implantation
rear surface converted into an n‐type by As implantation
creates a blocking electrical contact.
aluminum is evaporated and patterned by photolithography
thin electrical contacts
Detector is durable with good energy resolution characteristics
12
Solid State Detector • Germanium gamma detectors
Identify gamma energy through interaction with detector
• Planar configuration
electrical contacts to two flat surfaces on Ge disk
n contact from ion implantation or vapor diffusion of donor atoms on one surface
resulting n‐p junction is reverse biased
Limits active volume of detector
• Coaxial configuration
Electrode junction formed from outer and inner section of Ge cylinder
crystal cylinder can be extended in axial direction
much larger active volume
13
Gamma Detector
14
Detectors Based on Light Emission • Scintillation Counting
scintillations produced when particles strike fluorescent screen of ZnS
rays produce light
photosensitive electrode
output pulse from multiplier
• Organic Scintillators
any material that luminesces in suitable wavelength region when interacting with ionizing radiation
In liquid scintillators, solvent is main stopping medium for radiation
need to give efficient energy transfer to scintillating solute with little light absorption
wavelength shifters added to some scintillators
15
Light emission detectors • NaI(Tl) Scintillation Counters
high density of NaI and high Z of iodine make it an efficient -ray detector
pulse height spectra have same basic characteristics as those of semiconductor detectors
photopeaks, Compton distributions, annihilation radiation escape peaks
also has iodine escape peak at about 28 keV
* absorption of a ray near surface of detector and subsequent escape of a K-X ray of iodine
background rates high
16
Track Detectors
• Photographic Film
blackening or fogging of photographic negatives
nuclear emulsions show blackened grains along path
of each particle when exposed to ionizing radiations
number of developed grains per unit track
length is called grain density
smaller grain size, less sensitive emulsion to
anything but most densely ionizing particles
* Better resolution
17
Neutron Detectors
• Activation Methods
activation by (n,) reaction and subsequent measurement of induced radioactivity
Need to correct for activation by epithermal neutrons must be corrected for
• Ionization Chambers
charged particles emitted in neutron-induced reactions
for fast-neutron detection, H-containing filling gas used and produced recoil protons measured
• Proportional Counters
for integral measurement of thermal and epithermal neutrons
18
Neutron Detectors • Scintillation Counters
more efficient than gas-filled counter
but poor discrimination against rays
fast-neutron spectra determined via proton recoil measurements in solid or liquid organic scintillators
• Semiconductor Detectors
neutron counter obtained from semiconductor detector with “converter” material deposited on surface
Neutron drives formation of particle
cannot be used in high neutron fluxes due to deterioration
• Track Detectors
B- or Li-loaded photographic emulsions used for measurement of small fluxes of slow neutrons
when coated with fissile material, high sensitivity for neutron detection
19
Set of cores containing Pu hot particles
• Evaluate location of Pu in sediment
Identify by 241Am
• Obtained, surveyed, and segmented
Cylinders 5 cm diameter
15-31 cm length
• Samples segmented into 4-6 cm sections
• Prepared for gamma analysis
• Activity found as particle
Top 3 cm of cores
• Manual isolation of particle
20
Soil Sample and Hot Particle Activities
Soil Samples
1 – HP Removed
2 – HP Removed
3 – Adjacent to HP (2)
4 – HP Removed
5 – Adjacent to HP (4)
6 – Low Activity
7 – HP Removed
10
100
1000
104
105
106
107
1 2 3 4 5 6 7
Hot ParticleTotal Activity
1.2
10
6
6.5
10
4
4.5
6 1
04 2
.14 1
05
28.1
22
73.9
568
218
26
1.8
3 1
04
Lo
g A
cti
vit
y (
Bq
)
21
Optical Microscopy
X 200 X 500
X 1000 X 1000
22
SEM
SEI X150 SEI X500
SEI X1000 SEI X5000
23
SEM
BSC Dark Phase
(Ga-rich) BSC Bright phase
(Ga-depleted)
25
Past Future Present
Forensics Environmental
The Information Is Here
Questions
&
Interpretation
Where did it come
from?
Where is it
going? What is it?
Relationship between nuclear forensics and
environmental studies
• Characterization techniques for speciation, coordination, morphology
• Relate to goals of research
• Molecular/Chemical Forensic Science
Origin, Intent of Use, Storage Conditions, etc.
• Environmental/Remediation Information
26
Fundamental Problem How do we separate this?
From this?
100 um
Previous manual method not suitable
27
Dinosaurs, Rocks and the University of Texas
High Resolution X-ray CT Facility
Richard A. Ketcham Department of Geological Sciences
University of Texas at Austin
Ketcham, R.A., Carlson, W.D. Acquisition, optimization and interpretation of X-ray computed tomographic imagery: applications to the geosciences. Computers & Geosciences 27 (2001) 381-400
Identification of high Z actinide in low Z sediment
28
• 210 keV Beam at 0.13 mA
• 1000 views/rotation
• Slice Thickness=0.0743 mm
• Pixel Size=0.0635 mm x 0.0635 mm
• Voxel Volume = 2.9 x 10-4mm3
• 1024 x 1024 16-bit TIFF (2MB/slice)
• 8-bit JPEG (24kB/slice)
• 1500 – 3200 Slices Per Core
• Experiment Time: 2-3 hours
Depends upon core diameter
and desired size detection limit
C6-Slice 498 / 37 mm deep
Acquisition and Image Parameters
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Hot Particle Identification
0.6
mm
Blob x y z volume max row col slice 467 19 24 19 3315 149 151 368 806
106 7 7 4 112 122 563 572 221 203 10 12 10 565 81 309 292 377
30
70
90
110
130
150
170
190
210
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7
Identification of BlobsIntensity v Volume
Hot ParticlesBeadsUnknown
Maxim
um
Inte
nsity
Volume (mm3)
Limit of Detection
Minimum Intensity = 82
Minimum Volume =
0.006 mm3
Sphere
Diameter = 225 μm
Area in Image 16 Voxels
Analyzing the Blob Population
31
32
Core Disassembly
1 Stroke of the bottle jack = 3.45mm of vertical displacement
33
HP-2 HP-4
HP-19 HP-18 HP-14- 13379 cpm
HP-12 HP-11-1 HP-Roots Core-11 HP
HP-10 HP-7
HP-15
SEI Images of Hot Particles
34
Non-Rad Material
Volume = 6.352 mm3
Mass = 19.4 mg
Density = 3.05 g/cm3
Maximum Intensity =
78
35
Micro Particles from Core-14
Top Left: Secondary Electron Image
Bottom Left: Backscatter Image
Above: Enhanced Image Combined BSC and SEI
36 Energy (keV)
Micro Particles from Core-14 C
ounts
U Mα
U Mβ
Pu Mα
Pu Mβ
37
HP-4
38
HP-4
39
Elemental Mapping by X-ray Fluorescence Imaging
Experimental Setup at MR-CAT – Sector 10-IDB
X-ray
beam
Ionization
Chamber
KB Focusing
Mirrors
Ionization
Chamber
3 Axis Sample Stage
Sample
Cell
Optical
Microscope
4 Element SDD
(Si Drift Detector)
Scintillation
Detectors
Scintillation
Detectors Elements
Mapped
1.Am
2.Pu
3.U
4.Ga
5.Pb
Bent Laue
Analyzer
Small
Laue
Crystals
40
Optical Image –
200X
Pu Distribution
Am Distribution
U Distribution
Ga Distribution
41
XRF-SSRL (Particle #1)
42
XRF-SSRL (Particle #2)
43
U-EXAFS (Particle #1)
1.0
0.8
0.6
0.4
0.2
0.0
FT
Modulu
s
1086420 R-(Å)
Typical UO2 EXAFS
Particle #1 U-EXAFS
U-U ~ 3.85 Å
44
Pu-EXAFS (Particle #1)
0.8
0.6
0.4
0.2
0.0
-0.2
-0.4
-0.6
FT
Modulu
s
1086420R-(Å)
Data Fit O at 1.89 Å O at 2.27 Å O at 2.85 Å O at 3.16 Å O at 4.72 Å Pu at 3.77 Å
45
0
500000
1000000
1500000
2000000
2500000
3000000
3500000
4000000
4500000
5000000
0 200 400 600 800 1000 1200 1400 1600
Energy (keV)
Co
un
ts
0
5000
10000
15000
20000
25000
80 130 180 230 280 330 380 430 480
Energy (keV)
Co
un
ts
241-Am 59.5 keV (35.9%)
239-Pu 56.8 keV (0.001152%)
237-U 59.54 keV (34.5%)
Detector
Canberra GC3020
59.5mm HPGE
Closed End Coaxial
Hot Particle Gamma Spectroscopy
• Isotopics
• Dating
Limited by initial 241Am
Exploit 241Pu: 239Pu ratio
Determine 241Pu by 237U
BOMARC Pu origin year 1958±2
46
105 125 145 165 185 205
Pu-239:U-235 = 0.20
Pu-239:U-235 = 1.12
Pu-239:U-235 = 4.06
Pu-239:U-235 = 8.14
Pu-239:U-235 = 62.98
235U Variability
Energy (keV)
23
9-P
u 1
29
.29
ke
V (
0.0
06
31%
)
23
9-P
u 1
44
.20
ke
V (
2.8
3E
-4%
)
23
5-U
14
3.7
6 k
eV
(1
0.9
6%
)
23
5-U
16
3.3
3 k
eV
(5.0
8%
)
23
5-U
18
5.7
15 k
eV
(57
.2%
)
23
5-U
20
5.3
11 k
eV
(5.0
1%
)
47
Pu particles conclusions
• Use of Particles for Analysis
• X-Ray Techniques Useful for Forensics
• Fractionation/Separation, Mixing, Oxidation,
Location During Firing, Initial Info on
Weapon Design and Components
• Example of Traditional Nuclear Forensics
Combined with Molecular Techniques
• Valuable Data for Plutonium Library
• Proof of Concept for Techniques
Utility of speciation techniques
48
University of
Nevada, Las
Vegas
Radiochemistry
Radiochemistry Laboratories
49
UNLV Research Team
• Radiochemistry Faculty Ken Czerwinski (Chemistry) Ralf Sudowe (Health Physics) Gary Cerefice (Health Physics)
• Associate Faculty David Hatchett (Chemistry):
Electrochemistry Paul Forster (Chemistry): Inorganic
synthesis • Research Professors
Thomas Hartmann (Solid phase characterization)
Frederic Poineau (Tc chemistry) Eunja Kim(Computational)
• International Visiting Scientist Arunasis Bhattacharyya (BARC)
• Post-Doctoral Researcher Dan Rego (Synthesis)
• Graduate Students 26 graduate students
• Laboratory management Julie Bertoia, Trevor Low
50
US DOE Collaborators • Argonne National Laboratory (Alfred
Sattelberger, Associate Laboratory Director)
Tc coordination chemistry
• Los Alamos National Laboratory (Gordon Jarvinen, Kurt Sickafus, Carol Burns)
Actinide oxide aging for forensics
Tc-U Separations
Technetium waste forms
Education: Nuclear Forensics Summer School
1st school at UNLV in summer 2010
• NSTec (Amanda Klingensmith, Michael Mohar)
Nuclear Forensics and Environmental Pu chemistry
51
US DOE Collaborators • Idaho National Laboratory (Patricia Paviet-Hartmann,
Rory Kennedy) Fuel cycle separations and nuclear fuels
• Pacific Northwest National Laboratory (Edgar Buck, Herman Cho, Sam Bryan) Microscopy of tank waste solids and Tc waste forms NMR of Tc Actinide separations and spectroscopy
• Lawrence Berkeley National Laboratory (Wayne Lukens) Characterization of Tc compounds
• Livermore National Laboratory (Ian Hutcheon, Ken Moody) Nuclear forensics Heavy element chemistry
• Use of synchrotron and neutron diffraction facilities at Argonne, Berkeley, Los Alamos, Stanford, and Brookhaven
52
University Collaborations • Nuclear Science and Security Consortium
Coordinated by UC-Berkeley NE (http://nssc.berkeley.edu/) Training and education for nation’s
nuclear nonproliferation mission • NSF-IGERT
Hunter College/Sloan Kettering, University of Missouri Technetium-ligand interactions and
nuclear fuel cycle • Previous university collaborations
University of Wisconsin (ATR user facility: TEM)
MIT, UC Santa Barbara, University of Florida, Oregon State University, University of Idaho, University of Iowa
• Summer Schools Radiochemistry Fuel Cycle
6 week course at UNLV supported by DOE-NE
• International students Chimie Paris Tech University of Nantes Universite de Savoie
• Collaborations with students always welcomed!!
53
Research Program Concepts
• Chemistry based analysis of actinides and technetium Interested in chemical species and coordination
• Research areas Radiochemical materials synthesis and characterization Fuel cycle separations Radioanalytical separations
• Research with radionuclides Marco amount of Tc, Th, U, Np, Pu Submilligram quantity of Am and Cm
• Research coupled with education program Provide students with radioelement research opportunities
• Develop research excellence in radiochemistry Noted researchers, strong collaborations, interesting and
important projects • Center of radiological studies at UNLV Academic driven facility and research direction
54
Technology Maturation & Deployment
Applied Research
Molecular f-element
chemistry: structure and bonding
Response of molecules or ensembles of molecules to harsh environments
Chemistry and speciation in new media
Approaches to deconvoluting physical behavior in complex systems
Controlling An and FP chemistry
Creating selective receptor systems
Developing real-time sensing mechanisms
Controlling behavior of micellar systems
Discovery Research Use-inspired Basic Research
Modifying separation materials for durability in harsh environments
Prototype sensors
Demonstrating new separation systems at bench scale
Incorporating fundamental data to improve process models (AMUSE++)
Office of Science
BES Applied Energy Offices
EERE, NE, FE, TD, EM, RW, …
Codevelopment
Scale-up research
At-scale demonstration
Cost reduction
Prototyping
Manufacturing R&D
Deployment support
Goal: new knowledge/understanding
Mandate: open ended
Focus: phenomena
Metric: knowledge generation
Goal: practical targets
Mandate: restricted to target
Focus: performance
Metric: milestone achievement
Research Range
UNLV program range
55
Experimental Facilities
• Spectroscopy
XAFS, UV-Visible, Laser, NMR, IR, EELS
• Radiochemical separation and detection
Gross alpha/beta counting
α-spectroscopy
γ-spectroscopy
Scintillation Counting
• Thermal methods
TGA, DSC
56
Experimental Facilities
• Scattering
Powder XRD
Single crystal XRD
• Analytical
ICP-AES, ICP-MS, Electrospray-MS
Laser ablation sample introduction
available
• Microscopy
SEM, TEM
57
Research facilities at UNLV
• 10 laboratories and
counting rooms
Can work
with macro
amounts of
radionuclides
3 Low level
Instrumental
• Easy access
No limitations
on personnel
Simplified
training
58
Research Projects • TRISO Spent Fuel Behavior
• Quantification of UV-Visible and Laser Spectroscopic Techniques for Materials Accountability and Process Control
• Utilization of Methacrylates and Polymer Matrices for the Synthesis of Ion Specific Resins
• Development of Alternative Technetium Waste Forms
• Production and Characterization of Fe-Tc Alloys
• Synthesis of Actinide Oxides for Forensic Characterization
• Improved Retention of Tc in LAW Glass
• Rapid Automated Dissolution and Analysis Techniques for Radionuclides in Recycle Processed Streams
• Neutron Capture Measurements on 171Tm and 147Pm
• Synthesis and Characterization of Low Valent Tc compounds
• IGERT Education and Training: Radiopharmaceuticals
• Nuclear Forensics: Separations and Advanced Characterization Methods
• Synthesis and Characterization of Surrogate Nuclear Forensics Sources and Standards
• Characterization of Uranium-Zirconium Alloys
0.0
0.050
0.10
0.15
400 500 600 700 800 900
Ab
so
rb
an
ce
Wavelength (nm)
59
Recent Publications • Electrochemistry of soluble UO2
2+ from the direct dissolution of UO2CO3 in acidic ionic liquid containing water. Electrochim Acta., 93, 264-271 (2013). DOI: 10.1016/j.electacta.2013.01.044
• Trivalent Actinide and Lanthanide Complexation of 5,6-Dialkyl-2,6-bis(1,2,4-triazin-3-yl)pyridine (RBTP; R = H, Me, Et) Derivatives: A Combined Experimental and First-Principles Study. Inorganic Chem., 52(2), 761-776 (2013) DOI:10.1021/ic301881w
• Fluorescence and absorbance spectroscopy of the uranyl ion in nitric acid for process monitoring applications. J. Radioanal. Nucl. Chem., 295(2), 1553-1560 (2013) DOI:10.1007/s10967-012-1942-4
• Reactivity of HTcO4 with methanol in sulfuric acid: Tc-sulfate complexes revealed by XAFS spectroscopy and first principles calculations. Dalton Trans., 42(13), 4348-4352 (2013). DOI:10.1039/c3dt32951h
• The direct dissolution of Ce2(CO3)3 and electrochemical deposition of Ce species using ionic liquid trimethyl-n-butylammonium bis(trifluoromethanesulfonyl)imide containing bis(trifluoromethanesulfonyl)imide. Electrochim. Acta, 89, 144-151 (2013). DOI:10.1016/j.electacta.2012.10.083
• X-ray Crystallographic and First-Principles Theoretical Studies of K2[TcOCl5] and UV/Vis Investigation of the [TcOCl5]2- and
[TcOCl4]- Ions, Eur. J. Inorg. Chem., 2013(7), 1097-1104 (2013) DOI:10.1002/ejic.201201346
• Hydrothermal synthesis and solid-state structure of Tc2(m-O2CCH3)4Cl2, Polyhedron, 2012, http://dx.doi.org/10.1016/j.poly.2012.09.064.
• Technetium Chemistry in the Fuel Cycle: Combining Basic and Applied Studies, Inorg. Chem., 2012 dx.doi.org/10.1021/ic3016468
• Near infrared reflectance spectroscopy as a process signature in uranium oxides, J. Radioanal. Nucl. Chem., 1-5, 2012.
• Technetium tetrachloride revisited: A precursor to lower-valent binary technetium chlorides. Inorg. Chem., 51(15), 8462-8467 (2012).
• Probing the Presence of Multiple Metal−Metal Bonds in Technetium Chlorides by X-ray Absorption Spectroscopy: Implications for Synthetic Chemistry, Inorg. Chem., 51, 9563-957- (2012).
-Technetium Trichloride: Formation, Structure, and First-Principles Calculations. Inorg. Chem., 51(9), 4915-4917 (2012).
• First Evidence for the Formation of Technetium Oxosulfide Complexes: Synthesis, Structure and Characterization. Dalton Trans., 41(20), 6291-6298 (2012).
• Tetraphenylpyridinium Pertechnetate: a Promising Salt for the Immobilization of Technetium, Radiochim. Acta., 100, 325-328 (2012).
• X-ray absorption fine structure spectroscopic study of uranium nitrides. J. Radioanal. Nucl. Chem., 292, 989-994 (2012).
• Synthesis and Characterization of Th2N2(NH) Isomorphous to Th2N3. Inorg. Chem. 51, 3332-3340 (2012).
• Crystallographic structure of octabromoditechnetate(3−). Dalton Trans. 41(10), 2869-72 (2012).
• Dissolution behavior of plutonium containing zirconia-magnesia ceramics, J. Nucl. Mat. 422(1-3), 109-115 (2012).
• Crystal and Electronic Structures of Neptunium Nitrides Synthesized Using a Fluoride Route, J. Amer. Chem. Soc. 134(6), 3111-3119 (2012).
60
Acknowledgements • Cabrera Services
• Dr. A. Jeremy Kropf, Dr. Jeffery Fortner MR-CAT- APS/ANL
• Steve Conradson, LANL, SSRL
• U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. W-31-109-Eng-38
• U.S. Department of Energy/EPSCoR Partnership Grant, DE-FG02-06ER46295
• LLNL LDRD Contract DE-AC52-07NA27344