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

29

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