Radiation Detection

Radiation Detection

Ken Czerwinski

II Letnia Szkoła Energetyki i Chemii Jądrowej

Radiation Detection

Ken Czerwinski

Radiochemistry Program Department of Chemistry

University of Nevada, Las Vegas

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

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

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)

Multiplicative Ion Collection

• Increase of potential

changes detector behavior

• Proportional counter

 V ₁ to V ₂

 ratio of pulse heights for different ionizing events independent of applied voltage

• Above V ₃

 pulse height

independent of initial ionization

 Cannot differentiate particle

 Geiger-Mueller

counter region

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

a b f V

M ,

/

ln

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

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 E _g

thermal excitation leads to some conduction

positive hole created in valence band

energy  required to produce electron-hole

pair always exceeds E _g because some energy

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

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

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

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

Gamma Detector

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

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

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

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

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

Set of cores containing Pu hot particles

• Evaluate location of Pu in sediment

 Identify by ²⁴¹ Am

• 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

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

100 1000 10

10

10

10

Hot Particle Total Activity

1.2 106 6.5 104 4.56 104 2.14 105

28.1 22 73.9 568 218 26 1.83 104

L o g A c tiv it y ( B q )

Optical Microscopy

X 200 X 500

SEM

SEI X150 SEI X500

SEM

BSC Dark Phase (Ga-rich)

BSC Bright phase

(Ga-depleted)

Past Present Future

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.

Fundamental Problem

How do we separate this?

From this?

100 um

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

• 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 ^-4 mm ³

• 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

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

70 90 110 130 150 170 190 210

Identification of Blobs Intensity v Volume

Hot Particles Beads

Unknown

Ma ximu m I n te n s it y

Limit of Detection Minimum Intensity = 82

Minimum Volume = 0.006 mm ³

Sphere

Diameter = 225 μm

Analyzing the Blob Population

Core Disassembly

1 Stroke of the bottle jack = 3.45mm of vertical displacement

HP-2 HP-4

HP-12 HP-11-1

HP-Roots Core-11

HP

HP-10 HP-7

SEI Images of Hot Particles

Non-Rad Material

Volume = 6.352 mm

Mass = 19.4 mg

Density = 3.05 g/cm

Maximum Intensity =

78

Micro Particles from Core-14

Micro Particles from Core-14

Counts

U M

Pu M

Pu M

HP-4

HP-4

Elemental Mapping by X-ray Fluorescence Imaging Experimental Setup at MR-CAT – Sector 10-IDB

X-ray beam

Ionization Chamber

KB Focusing

Ionization Chamber

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

Optical Image – 200X

Pu Distribution Am Distribution

U Distribution

Ga Distribution

XRF-SSRL (Particle #1)

XRF-SSRL (Particle #2)

U-EXAFS (Particle #1)

1.0 0.8 0.6 0.4 0.2 0.0

FT M odu lus

10 8

6 4

2

0 R-  (Å)

Typical UO ₂ EXAFS Particle #1 U-EXAFS

U-U ~ 3.85 Å

Pu-EXAFS (Particle #1)

0.8 0.6 0.4 0.2 0.0 -0.2 -0.4 -0.6

FT M odu lus

10 8

6 4

2

0 R-  (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

500000 1000000 1500000 2000000 2500000 3000000 3500000 4000000 4500000 5000000

Counts

0 5000 10000 15000 20000 25000

80 130 180 230 280 330 380 430 480

Energy (keV)

Counts

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

Am

 Exploit

Pu:

Pu ratio

 Determine

Pu by

U

 BOMARC Pu origin year 1958±2

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

235 U Variability

239-Pu 129.29 keV (0.00631%) 239-Pu 144.20 keV (2.83E-4%) 235-U 143.76 keV (10.96%) 235-U 163.33 keV (5.08%) 235-U 185.715 keV (57.2%) 235-U 205.311 keV (5.01%)

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

University of Nevada, Las

Vegas

Radiochemistry

Radiochemistry Laboratories

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

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

 1 ^st school at UNLV in summer 2010

• NSTec (Amanda Klingensmith, Michael Mohar)

 Nuclear Forensics and Environmental Pu

chemistry

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

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!!

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

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

Goal: practical targets Mandate: restricted to target Focus: performance

Research Range

UNLV program range

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

Experimental Facilities

• Scattering

 Powder XRD

 Single crystal XRD

• Analytical

 ICP-AES, ICP-MS, Electrospray-MS

Laser ablation sample introduction available

• Microscopy

 SEM, TEM

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

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

Tm and

Pm

• 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

0.0 0.050 0.10 0.15

400 500 600 700 800 900

Absorbance

Wavelength (nm)

Recent Publications

• Electrochemistry of soluble UO₂²⁺ 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).

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