The document presents an introduction to a master's thesis that aims to design a neutron detector to replace 3He detectors using thin polymeric films. It discusses the need to replace 3He detectors due to shortages and outlines detector requirements. It introduces various neutron detection reactions and interactions of interest. Methods for characterizing detector performance are described, including analyzing spectra from calibration sources at different facilities, determining pulse height deficit, light yield, and intrinsic gamma efficiency. Simulation methods and models are also discussed.

1. Introduction Spectra Methods PSD Methods Simulation Methods Film Performance Simulation Results PSD Performance
Design of a Neutron Detector Capable of
Replacing 3He Detectors Utilizing Thin
Polymeric Films
Matthew Urffer1
1 Department of Nuclear Engineering
University of Tennessee, Knoxville, TN
Master’s Thesis Defense, 2012

2. Introduction Spectra Methods PSD Methods Simulation Methods Film Performance Simulation Results PSD Performance
Outline
1 Introduction
Radiation Portal Monitors
Detector Requirements
Previous Work
2 Spectra Methods
Facilities
Analysis Methods
3 PSD Methods
PSD Introduction
4 Simulation Methods
Simulation Methods
Simulation Validation
5 Film Performance
Examples
Performance Tables
6 Simulation Results
Single Film

3. Introduction Spectra Methods PSD Methods Simulation Methods Film Performance Simulation Results PSD Performance
US Border Traffic
Every day 932,456
people cross into the
US [1]
259,191 by air
48,073 by sea
621,874 by land
64,483 truck, rail and
sea containers [1]
253,821 Figure: Portal Entry Points into
privately-owned the U.S.
vehicles [1]

4. Introduction Spectra Methods PSD Methods Simulation Methods Film Performance Simulation Results PSD Performance
Radiation Portal Monitors
Radiation portal
monitors (RPMs) are
passive radiation
detectors
RPMs are currently 3 He
based detectors
3 He + n → p + 3H
Shortage of 3 He, so
alternatives are being
Figure: Installed RPM
explored

5. Introduction Spectra Methods PSD Methods Simulation Methods Film Performance Simulation Results PSD Performance
Neutron Adsorption Interactions
Desired reaction properties
High probability of occurrence
Ease of detecting reaction products
Reaction products have a low pulse height deficit
Reaction Q-Value (MeV) Thermal Cross Section Application
3
He + n → p + 3 H 0.756 5,330 Proportional counter gas
6
Li + n → 3 H + α 4.78 940 Lithium glass scintillators
10
B + n → α + 7 Li 2.31 3,840 Plastic Scintillators
157
Gd + n → γ various 259,000 various

6. Introduction Spectra Methods PSD Methods Simulation Methods Film Performance Simulation Results PSD Performance
Energy Deposition (Charged Particle)
Products of 6 Li neutron interaction are triton and alpha:
Alpha
Proton
1
0.1
0.01
Alpha Energy: 2.05 MeV
Range (g/cm )
2
1E-3
Triton Energy: 2.73 MeV 1E-4
Alpha and tritons tend to
1E-5
1E-6
deposit all of there energy in 1E-7
1E-4 1E-3 0.01 0.1 1 10
a small region Energy (MeV)
Figure: Alpha and Triton
Range (CSDA) [2]

7. Introduction Spectra Methods PSD Methods Simulation Methods Film Performance Simulation Results PSD Performance
Detector Requirements
DHS / DNDO (along with PNNL) has determined a set of
objectives that replacement technologies should meet:
Parameter Specification
Absolute neutron detection efficiency 2.5 cps/ng of 252 Cf (in specified test configuration)
Intrinsic gamma-neutron detection efficiency ǫint,γ <= 10−6
Gamma absolute rejection ratio for neutrons (GARRn) 0.9 <= GARRn <= 1.1 at 10 mR/h exposure
Cost $ 30,000 per system

8. Introduction Spectra Methods PSD Methods Simulation Methods Film Performance Simulation Results PSD Performance
Absolute Neutron Efficiency
Absolute Neutron Efficiency
Counts
ǫabs = [3]
Quanta Radiation Emitted
Constraint:
ǫabs ≥ 2.5cps per ng252 Cf
Test configuration is defined to be 1 ng 252 Cf surrounded by 0.5
cm of lead and 2.5 cm of HDPE, with the detector midpoint 2 m
from the source [4]

9. Introduction Spectra Methods PSD Methods Simulation Methods Film Performance Simulation Results PSD Performance
Intrinsic Gamma-Neutron Detection Efficiency
Intrinsic Gamma-Neutron Detection Efficiency
Counts
ǫint,nγ = [4]
Quanta Radiation Crossing Detector
Constraint:
ǫint,nγ ≤ 10−6
Counts over quanta crossing the detector
Measured from a source that produces a 10 mR/hr field

10. Introduction Spectra Methods PSD Methods Simulation Methods Film Performance Simulation Results PSD Performance
Gamma Absolute Rejection Ratio
GARRn
ǫγ,abs
GARRn = [4]
ǫn,abs
Constraint:
0.9 ≤ GARRn ≤ 1.1
The detector’s performance should change by no more than
10% in a strong gamma field
GARRn is measured by exposing the detector to a 10
mR/hr gamma field while exposed to neutron source
Count rate is measured when the gamma source is no
longer present
Difference determines the GARRn

11. Introduction Spectra Methods PSD Methods Simulation Methods Film Performance Simulation Results PSD Performance
Replacement Technologies (Boron)
Boron Straw Fibers
(Proportional Technology)
[5]
Count rate meets requirements
Gamma rejection is estimated to be
4x10−9 Figure: B10 Straw Fibers
GARRn within desired range
Boron Triflouride Gas
Detectors (LND) [6]
Two tubes are marginally able to
replace one 3 He tube
BF3 Tubes require 2200V to
operate than 3 He tubes (1000 V)
BF3 Tubes require less pressure
than 3 He tubes
Figure: PNNL test of BF3
Detector

12. Introduction Spectra Methods PSD Methods Simulation Methods Film Performance Simulation Results PSD Performance
Replacement Technologies (Lithium)
LiF:ZnS coated Paddles
(IAT) [7]
Did not fulfill the neutron count rate
Adequate gamma ray rejection
Passed the GARRn Figure: 6 LiF:ZnS Paddle
NucSafe Glass Fibers[4]
Tested with a scale model, 1.72 cps
Three filter levels for GARRN
Conservative filter passed
GARRn, failed count rate
Other filters failed GARRn
Figure: NucSafe Fibers

13. Introduction Spectra Methods PSD Methods Simulation Methods Film Performance Simulation Results PSD Performance
Button Sources
Alpha Sources
Source Half-Life Energy (MeV)
232
Th 1.4 × 1010 yr 4.012
240
Pu 6.5 × 103 yr 5.17 (76%) 5.12 (24%)
241
Am 433 yr 5.48 (85%) 5.44 (12%)
239
Pu, 241 Am, 244 Cm various various
Beta Sources
Source Half-Life Endpoint Energy (MeV)
14
C 5,730 yr 0.156
36
Cl 3.08 × 105 yr 0.714
36
Ni 92 yr 0.067
99
Tc 2.12 × 105 yr 0.292

14. Introduction Spectra Methods PSD Methods Simulation Methods Film Performance Simulation Results PSD Performance
Gamma Irridiator
Desire a 10 mR/hr
Gamma Field
Solution is 1 100 µCi
60 Co source
Shielded by lead
Figure: Gamma Irridiator

15. Introduction Spectra Methods PSD Methods Simulation Methods Film Performance Simulation Results PSD Performance
Neutron Irridiator
Source is 0.59 µg 252 Cf Figure: CAD Rendering of
Encased in HDPE Box Neutron Irridiator
Two detector wells
Lead Well
Cadmium Well
Figure: MCNPX Rendering of
Neutron Irridiator

16. Introduction Spectra Methods PSD Methods Simulation Methods Film Performance Simulation Results PSD Performance
Neutron Irridiator (Spectra)
Lead Well
Cadmium We
Lead Well 1
Cf)
Neutrons of all energies
252
Lead to match photon attenuation
Neutron Flux (neutrons per ng
of cadmium 0.1
Cadmium Well
Cadmium cutoff is about 0.5 eV 0.01
Well response is to fast neutrons
Shielding of photons from cadmium
Subtraction is preformed 1E-3
between the two response
to extract the response 1E-9 1E-8 1E-7 1E-6 1E-5 1E-4 1E-3 0.01
Neutron Energy (MeV)
0.1 1 10 100
from thermal neutrons
Figure: Simulated Lead and
Cadmium Well Spectra

17. Introduction Spectra Methods PSD Methods Simulation Methods Film Performance Simulation Results PSD Performance
Spectra Electronics
Measurement Protocol
Verify instrument gains are stable Detector Pre Amplifier Amplifier
(Philips XP2022B PMT) (Canberra 2007P ) (Ortec 572A)
GS20 (6 Li glass) is used as the
standard
ADC-MCB
Set voltage and coarse gain, adjust HV Power Supply
(Ortec 556)
(Ortec 926)
fine gain
Obtain a spectra from an alpha (241 Am)
Obtain a spectra from a beta (36 Cl) MAESTRO-32 Software
Obtain a lead well neutron spectra Figure: Electronic Setup for
Obtain a cadmium well neutron spectra Spectra
Obtain a gamma irridiator spectra

18. Introduction Spectra Methods PSD Methods Simulation Methods Film Performance Simulation Results PSD Performance
Spectra Average
Thin films do not have clearly define features
Spectra averages defined to create a feature
Spectra Average
∞
0 xf (x)dx
< µ >= ∞
0 f (x)dx
where:
< µ > is the average of the spectra
f (x) is the spectra
x is a channel number

19. Introduction Spectra Methods PSD Methods Simulation Methods Film Performance Simulation Results PSD Performance
Pulse Height Deficit
Pulse Height Deficit
npeak
PHDGS20 = 4.78 MeV
CEγ
1.038 MeV
where:
PHDGS20 is the pulse height deficit for GS20
npeak is the location of the peak in the neutron spectra
CEγ is the Compton Edge of the Gamma Spectra
Pulse Height Deficit (Sample)
< n >sample
PHDSample = PHDGS20
< n >GS20
where:
PHDGS20 is the pulse height deficit for GS20
< n >sample is the average of the sample’s neutron spectra
< n >GS20 is the average of GS20’s neutron spectra

20. Introduction Spectra Methods PSD Methods Simulation Methods Film Performance Simulation Results PSD Performance
Light Yield
Light Yield
Photons < n >sample
LYn = 3, 800
MeV < n >GS20
Photons < β >sample
LYβ = 3, 800
MeV < β >GS20
Photons < γ >sample
LYγ = 3, 800
MeV < γ >GS20
where:
< n >sample is the average of the sample’s neutron spectra
< n >GS20 is the average of GS20’s neutron spectra
< β >sample is the average of the sample’s beta (36 Cl) spectra
< β >GS20 is the average of GS20’s bet (36 Cl) spectra
< γ >sample is the average of the sample’s gamma (60 Co) spectra
< γ >GS20 is the average of GS20’s gamma (60 Co) spectra

21. Introduction Spectra Methods PSD Methods Simulation Methods Film Performance Simulation Results PSD Performance
Gamma Intrinsic Efficiency
∞
f (x)dx
MLLD
ǫint,γ =
Particles Incident
where:
MLLD is the mathematical lower level discriminator
f (x) is the spectra
Particles Incident is the number of incident particles
Mathematical Lower Level Discriminator
Mathematical lower level discriminator (MLLD) is defined to be the channel at which ǫint,γ ≤ 10−6
MLLD for a film is determined from a 60 Co measurement
Source produces a 10 mR/hr field at detector surface
Particles incident determined from simulation

22. Introduction Spectra Methods PSD Methods Simulation Methods Film Performance Simulation Results PSD Performance
Gamma Intrinsic Efficiency Example I
Integrate above each MLLD
60
Co spectra divide by flux
1000 0.01
1E-3
100
Co Intrinsic Efficiency
1E-4
Co Count Rate (cps)
10
1E-5
1
1E-6
0.1
60
1E-7
60
0.01
1E-8
1E-3
1E-9
1E-4 1E-10
0 1000 2000 3000 4000 5000 6000 0 2000 4000 6000 8000
Channel Number (50 G) MLLD
Locate MLLD for which
Compute neutron count rate
0.20
Cf Net Count Rate (cps)
0.15 above the MLLD - MLDD for 1 in a million gamma
discrimination
0.10
- Fraction of neturon counts above
0.05 the MLLD
252
0.00
0 2000 4000 6000 8000
Channel Number (50 G)
Figure: Determination of the MLLD (Example)

23. Introduction Spectra Methods PSD Methods Simulation Methods Film Performance Simulation Results PSD Performance
Gamma Intrinsic Efficiency Example II
Integrate above each MLLD
60
Co spectra divide by flux
0.01
Gamma Intrinsic Efficiency
1E-3
1E-4
1E-5
1E-6
0 1 2 3
Bin
Locate MLLD for which
10
Compute neutron count rate
above the MLLD - MLDD for 1 in a million gamma
8
discrimination
Neutron Count Rate
6 - Fraction of neturon counts above
4
the MLLD
2
0
0 1 2 3 4
Bin
Figure: Determination of the MLLD for a PEN film

24. Introduction Spectra Methods PSD Methods Simulation Methods Film Performance Simulation Results PSD Performance
Introduction to PSD
Determination of incident radiation from pulse shape
Physical basis
Difference in singlet (S1 ) and triplet (T1 ) states [8]
Triple states annihilate: T1 + T1 → S0 + S1
Product states have a longer and delayed time scale
Short range of energetic protons (neutron interactions) cause a
high concentration of triplet states than from electrons from
gamma
Lots of methods exist [9, 10, 11]
Charge Integration
Pulse Gradient Analysis
Neutron-γ Modal Analysis
Pulse Shape Parameters
Artificial Neural Networks
and more!

25. Introduction Spectra Methods PSD Methods Simulation Methods Film Performance Simulation Results PSD Performance
Pulse Height Electronics
Pulse traces are recorded either from an oscilloscope or from
fast digitilizer
Requires fast PMT and electronics
Oscilloscope
Detector PMT Base Dynode (Agilent MSO-X 3034A)
(Philips XP2022 PMT) (S563)
Fast PreAmp
Ortec 142A
HV Power Supply
(Ortec 556)
Write to disc
Fast Digitizer
Agilent U1064A
Acqiris Live
Figure: Electronic Setup for Pulse Shape

26. Introduction Spectra Methods PSD Methods Simulation Methods Film Performance Simulation Results PSD Performance
PSD Methods
Alpha are used as surrogate
neutrons
Charge Ratio Method V
∞
X0 f (x)dx
RC = ∞
0 f (x)dx
where:
t
RC is the charge ratio
f (x) is the spectra Figure: Charge Ratio Method
∞
X0 f (x)dx slow charge
∞
0 f (x)dx fast charge
MLLD for a film is determined from a 60 Co measurement
Source produces a 10 mR/hr field at detector surface
Particles incident determined from simulation

27. Introduction Spectra Methods PSD Methods Simulation Methods Film Performance Simulation Results PSD Performance
ROC Curves I
True Class
Hypothesized Class Alpha Gamma
False
Alpha True Positive Positive
(Type 1)
False
True
Gamma Negative
Negative
(Type 2)
FP
FN
FP
TP
TP TN
TN
TN TP
FN FN FP
Figure: Performance of a Classifier

28. Introduction Spectra Methods PSD Methods Simulation Methods Film Performance Simulation Results PSD Performance
ROC Curves II

29. Introduction Spectra Methods PSD Methods Simulation Methods Film Performance Simulation Results PSD Performance
ROC Curves III
=1/2, =4
=1/2, = 8
1.0
1.4
0.8
1.2
0.6 1.0
0.8
0.4
0.6
0.4
0.2
0.2
True Postive Rate
0.0
0.0
-0.2
-1 0 1 2 3 4 5 6 7 8 9 10 11 -1 0 1 2 3 4 5 6 7 8 9 10 11
0.5
Score Score
=1/2, =4 =1/2, =5.5
=1/2, = 6 =1/2, = 6
0.8 0.8
Distributions A
0.6 0.6
Distributions B
Distributions C
0.4 0.4 Distributions D
0.0
0.2 0.2
0.0 0.5 1.0
False Postive Rate
0.0 0.0
-1 0 1 2 3 4 5 6 7 8 9 10 11 -1 0 1 2 3 4 5 6 7 8 9 10 11
Score Score
Figure: ROC Curves of the
Figure: Gaussian Classifiers
Four Classifiers

30. Introduction Spectra Methods PSD Methods Simulation Methods Film Performance Simulation Results PSD Performance
Gamma Irridiator Dose Rate
Need to create a 10 mR/hr field
Dose Rate Calculation
1
F2 = dA dE ∈4π dΩℜ(E)Φ(r , E, Ω)
A A E
where:
ℜ(E) is the response function
Φ(r , E, Ω) is the photon flux
Accomplished using the DF Cards
c M u l t i p l y each t a l l y by 1000 mrem / rem ∗ 100 uCi ∗ 3 . 7 E10 Bq ∗2 photons / decay
FC12 Photon F l u x over F r o n t o f D e t e c t o r Surface
F12 : P (500.2 <600)
DE12 0.01 0.015 0.02 0.03 0.04 0.05 0.06 0.08 0 . 1 0.15 0 . 2 0 . 3 0 . 4 0 . 5 0 . 6
0.8 1 1.5
DF12 2.78E−6 1.11E−6 5.88E−7 2.56E−7 1.56E−7 1.20E−7 1.11E−7 1.20E−7 1.47E−7
2.38 e−7 3.45E−7 5.56E−7 7.69E−7 9.09E−7 1.14E−6 1.47E−6 1.79E−6 2.44E−6

31. Introduction Spectra Methods PSD Methods Simulation Methods Film Performance Simulation Results PSD Performance
Interaction Rate
Interaction Rate
Q =C Φ(E)Rm (E)dE
where:
Q is an arbitrary scalar normalization
Rm (E) is the response function
Φ(E) is the photon flux
Accomplished using a F4 tally with multiplier
c − − − − − − − I n t e r a c t i o n Rate T a l l i e s − − − − − − − − − − − −
−−−−−−− −−−−−−−−−−−
FC114 T o t a l Neutrons Reactions i n D e t e c t o r i n Pb Well
F114 : n (601 <610)
FM114 −1 3 1
FC154 ( n , t ) Reactions i n D e t e c t o r i n Pb Well
F154 : n (601 <610)
FM154 −1 3 105
FC214 T o t a l Neutron Reactions i n D e t e c t o r i n Cd Well
F214 : n (601 <620)
FM214 −1 3 1
FC254 ( n , t ) Reactions i n D e t e c t o r i n Cd Well
F254 : n (601 <620)
FM254 −1 3 105

32. Introduction Spectra Methods PSD Methods Simulation Methods Film Performance Simulation Results PSD Performance
Neutron Simulation Agreement
Simulated Count Observed Count
Relative Error
Rate Rate
GS20 424.83 ± 3.8% 428 -0.7 %
PS Film, 25 µm 56.23 ± 1.19% 51 9.5%
PS Film, 50 µm 108.10 ± 1.14% 96 12.6%
Definition (Relative Error)
Obs − Sim
σ=
Obs
where:
Obs is the observed count rate
Sim is the simulated count rate

33. Introduction Spectra Methods PSD Methods Simulation Methods Film Performance Simulation Results PSD Performance
Example Spectra
Figure: PEN Neutron Spectra Figure: PEN Gamma Spectra

34. Introduction Spectra Methods PSD Methods Simulation Methods Film Performance Simulation Results PSD Performance
Neutronic and Gamma Efficiency Performance
Neutron Count Rate
Total Neutron Count
Absorber Mass (mg) above
Rate (cps)
ǫint,γ ≤ 10−6 (cps)
PEN 50 % LiF 1% ADS156FS
9.10 53.04 11.45
(stretched)
PEN 70 % LiF 25%
PPO/POPOPOP 5 % (158 19.6 92.4 21.2
µm Annealed)
PS LiF 10% PPO/POPOPOP 5
1.37 8.25 2.25
% (26 µm Annealed)
PS LiF 30% PPO/POPOPOP 5
9.33 82.64 1.01
% (50 µm)
EJ-426 HD2 (LiF in Zens:Ag) 105 568.3 24.56

35. Introduction Spectra Methods PSD Methods Simulation Methods Film Performance Simulation Results PSD Performance
Light Yield Performance
Alpha Beta Photons Photons Photons
Average α
Peak <β> per MeV per MeV per MeV
(241 Am) (36 Cl) (Gamma) (Beta) (Neutrons)
PEN 50 % LiF
1% ADS156FS 2,590 355 0.34 500 916 1,560
(stretched)
PEN 70 % LiF 25%
PPO/POPOPOP 5 % 2,880 765 0.18 1,400 1,670 2,500
(158 µm Annealed)
PS LiF 10%
PPO/POPOPOP 5 % 4,070 345 0.55 1,350 1,540 1,500
(26 µm Annealed)
PS LiF 30%
PPO/POPOPOP 3,490 393 0.41 1,140 1,120 1,120
5 % (50 µm)
EJ-426 HD2 (LiF in
19,750 26,900
ZnS:Ag)

36. Introduction Spectra Methods PSD Methods Simulation Methods Film Performance Simulation Results PSD Performance
Single Film Model
Test configuration
mocked up in MCNPX
Single film simulated
Steel Encasing (1/8”)
Reflector (Arcylic) 7 cm
Thin Film Detector
Moderator (HDPE) 5 cm
Figure: Simulated RPM8
Detector Figure: Source and incident
Spectra

37. Introduction Spectra Methods PSD Methods Simulation Methods Film Performance Simulation Results PSD Performance
Single layer optimization
Minimal optimization of the detector assembly was preformed
Study on RPM8 encasing material
Study on moderator and reflector thickness
Count rate was too low
1 cm
2 cm
-5
2.0x10
3 cm
4 cm
-5
3
1.8x10
(n,triton) Interaction Rate per Source Neutron per cm
5 cm
6 cm
-5
7 cm
1.6x10
8 cm
-5 9 cm
1.4x10
10 cm
11 cm
-5
1.2x10 12 cm
13 cm
-5
1.0x10
-6
8.0x10
-6
6.0x10
-6
4.0x10
-6
2.0x10
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Front HDPE Moderator Thickness (cm)
Figure: Optimal Reflector and Moderator Study

38. Introduction Spectra Methods PSD Methods Simulation Methods Film Performance Simulation Results PSD Performance
Effects of Layering I
Single films are unable to have a high enough count rate
Solution: Multiple films!
Effects of layering multiple films tested with EJ-426HD2
A
B C
A - Unwrapped Single 6LiF loaded ZnS:Ag
B - Single 6LiF loaded ZnS:Ag Sheet
sheet. The sheet is sandwiched between
(1.4” x 1.4”) wrapped in Teflon tape
two PMMA slabs, with the narrow edge opti-
(white), and gaffer tape (black).
cally coupled to the PMT. The yellow sponge
is provide for support.
A - Four sheets of 6LiF loaded ZnS:Ag separated by
PMMA, already wrapped in Teflon and gaffer tape. B -
Assembled detector in sponge for support. C - Assem-
bled detector atop PMT.

39. Introduction Spectra Methods PSD Methods Simulation Methods Film Performance Simulation Results PSD Performance
Effects of Layering II
Observe an increased neutron count rate . . .
Figure: Neutron Spectra of EJ426HD2

40. Introduction Spectra Methods PSD Methods Simulation Methods Film Performance Simulation Results PSD Performance
Effects of Layering III
with only a minimal increase in the gamma response!
60
-3
x 10 Gamma (Co ) Response of ZnS:Ag Detectors
6
Mutliple Vertical
Single Vertical
Single Hortizontal
5
4
Count Rate (cps)
3
2
1
0 1000 2000 3000 4000 5000 6000 7000 8000
Channel Number
Figure: Gamma Spectra of Figure: Gamma Intrinsic
EJ426HD2 Efficiency of EJ426-HD2

41. Introduction Spectra Methods PSD Methods Simulation Methods Film Performance Simulation Results PSD Performance
Multi Film Model
120 50µm PS Films simulated
Figure: Source and Incident
Spectra
Figure: Simulated RPM8
Detector (120 layers)

42. Introduction Spectra Methods PSD Methods Simulation Methods Film Performance Simulation Results PSD Performance
Minimum Number of Films
Minimum number of films needed was calculated
38 for LiF ZnS:Ag
74 for PEN
110 for PS
EJ426HD2
Composite PEN
Composite PS
3
Cf (cps)
252
2.1 cps
Interaction Rate Per ng
2
1
0 20 40 60 80 100
Number of Layers
Figure: Minimum Required Layers

43. Introduction Spectra Methods PSD Methods Simulation Methods Film Performance Simulation Results PSD Performance
PSD Performance (PS Films I)
Enhanced performance can be achieved with PSD (theoretically)
PS films show some ability for PSD
None of the films are optimized [8]
PS 15% PPO 10% LiF 50 µm
PS 15% PPO 15% LiF 151µm PS 15% PPO 15% LiF 151µm
25
25 25
Alpha
Alpha Alpha
Gamma
Gamma Gamma
20 20 20
µ = 0.424
σ = 0 .027
15 15 15
Frequency
Frequency
Frequency
µ = 0.458 µ = 0.458
σ = 0 .036 σ = 0 .036
µ = 0.405 µ = 0.405
µ = 0.392 σ = 0.048 σ = 0.048
10 σ = 0.062 10 10
5 5 5
0 0
0 0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.6 0.65 0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.6 0.65
0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.6 0.65
Charge Ratio (Q /Q ) Charge Ratio (Q /Q )
Charge Ratio (QSlow / QTotal) Slow Total Slow Total
Figure: PS 10% LiF Figure: PS 10% LiF Figure: PS 15% LiF
50 µm 150 µm 150 µm

44. Introduction Spectra Methods PSD Methods Simulation Methods Film Performance Simulation Results PSD Performance
PSD Performance (PS Films II)
Thicker films tend to have better PSD
Additional LiF decrease PSD performance
Performance of Charge Ratio Classifer
1
0.9
1
0.8
0.9
0.7
0.8
True Postive Rate
0.6
0.7
PS 15% PPO 150µm
False Postive Rate
0.5
0.6
PS 15% PPO 10% LiF 50µm
0.4
PS 15% PPO 15% LiF 150µm 0.5
0.3 PS 15% PPO 15% LiF 150µm
0.4
0.2
PS 15% PPO 10% LiF 50µm PS 15% PPO 150µm
0.3
0.1
0.2
0
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
0.1
False Postive Rate
0
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
Fraction of Alpha Counts
Figure: ROC Curves of Charge
Integration Classifier (PS Figure: Possible Configuration
Films)

45. Introduction Spectra Methods PSD Methods Simulation Methods Film Performance Simulation Results PSD Performance
PSD Performance (PEN Films)
PEN films demonstrated little capability for PSD
PEN films where mounted on Katpon, which scintillates
None of the films are optimized [8]
1
0.9
0.8
0.7
True Postive Rate
0.6
0.5
PEN on Kapton
0.4
0.3 PEN 15% PPO
Kapton
0.2
PEN
0.1
0
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
False Postive Rate
Figure: ROC Curves of Charge Integration Classifier (PEN Films)

46. Introduction Spectra Methods PSD Methods Simulation Methods Film Performance Simulation Results PSD Performance
Summary
A framework has been developed for the characterization
of possible replacement technologies for radiation portal
monitors
A framework has been developed for pulse shape
discrimination
Thin polymeric films have been demonstrated to have the
necessary interaction rates for radiation portal monitors

47. Introduction Spectra Methods PSD Methods Simulation Methods Film Performance Simulation Results PSD Performance
Works Cited I
CPB, “On a typical day in fiscl year 2011 CBP.” http://www.cbp.gov/xp/cgov/about/, 2012.
M. Berger, J. Coursey, M. Zucker, and J. Chang, “ESTAR, PSTAR and ASTAR: computer programs for
calculating stopping-power and range tables for electrons, protons, and helium ions,” 2005.
G. F. Knoll, Radiation Detection and Measurement.
New York: Wiley, 2009.
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48. Introduction Spectra Methods PSD Methods Simulation Methods Film Performance Simulation Results PSD Performance
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49. Appendix
Absorption Cross Sections
He-3
8 Li-6
10
B-10
7 Gd-157
10
(n,total) cross section (barns)
6
10
5
10
4
10
3
10
2
10
1
10
0
10
-1
10
-6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9
10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10
Energy (Mev)