Brookhaven Science AssociatesU.S. Department of Energy

Stand-off Nuclear Radiation Detection

Peter E. VanierDetector Development and Testing Div.

Nonproliferation and National Security Dept.Brookhaven National Laboratory

Presented at the 18th Annual NDIA

Special Operations / Low Intensity Conflict Symposium and Exhibition

Hyatt Crystal CityFebruary 26 –28, 2007

BROOKHAVEN NATIONAL LABORATORY SITEBROOKHAVEN NATIONAL LABORATORY SITE

• Established in 1947 on Long Island, Upton, New York, Brookhaven is a multi-program national laboratory operated by Brookhaven Science Associates for the U.S. Department of Energy (DOE).

• Six Nobel Prizes have been awarded for discoveries made at the Lab.

• Brookhaven has a staff of approximately 3,000 scientists, engineers, technicians and support staff and over 4,000 guest researchers annually.

• Brookhaven National Laboratory's role for the DOE is to produce excellent science and advanced technology with the cooperation, support, and appropriate involvement of our scientific and local communities.

Collision of gold nuclei at RHIC

Camp Upton

Lab work with Industry:Radiation Portal Monitor Testing and Evaluation

Lab work with Industry:Radiation Portal Monitor Testing and Evaluation

Lab work with Industry:Cadmium Zinc Telluride material evaluation

Lab work with Industry:Cadmium Zinc Telluride material evaluation

Synchrotron Radiation

10-µm pinhole

10x10-μm2

beam

CZT planar detector

Translation stage

Correlations between x-ray map & IR imageThis x-ray map shows the degraded regions precisely correspond to Te precipitates on the right

This IR image shows Te precipitates, which could be identified by shape with IR microscope

100% correlations were found for all CZT samples tested in this work.

Lab Work with Industry – Compressed Xenon Spectrometers

0

20

40

60

80

100

120

140

100 150 200 250 300 350 400 450 500

ENERGY (keV)

375 keV

414 keV

451 keV

208 keV

333 - 345 keV

Pu-239 spectrum using xenon

Operate at room temperatureSufficient resolution to identify isotopesScalable to large volumes - increased sensitivityIdentify special nuclear materialsAllow passage of medical isotopesAllow naturally occurring radioactive materialsReduce false positive rate

planar design

CTC coaxial design

Microelectronics Group

AREAS OF EXPERTISE• CMOS monolithic circuits

• charge-sensitive sensor interface

• analog signal processing

• low noise, low power techniques

• VLSI custom design + layout

High-speed, radiation-tolerant sampling/digitizing board

Gamma Imaging

National Security

Gamma spectrometer for detection of nuclear materials

Gamma spectrometer for detection of nuclear materialsPositron emission tomograph for

imaging the awake animal brain Positron emission tomograph for imaging the awake animal brain

240-channel multichip module for Si drift detector readout

240-channel multichip module for Si drift detector readout

Handheld imaging probe for gamma radiation

Handheld imaging probe for gamma radiation

0 200 400 600 800 1000 12000

200

400

60057CoFWHM ≈ 3.8% at 122keV

CZT 3x3x7 mm3

Peaking Time τP ≈ 1.2µs

Cou

nts

Channel

57Co spectrum

CZT pixel

reset

high-ordershaper

baseline stabilizer

to external ADC

amplitude and timing extractor

chargepreamplifier

shaper back-end processing & data concentration

CZT pixel

reset

high-ordershaper

baseline stabilizer

to external ADC

amplitude and timing extractor

chargepreamplifier

shaper back-end processing & data concentration

Preamplifier/shaper ASIC block diagramPreamplifier/shaper ASIC block diagram

Low-power ASICs

p+ substratep- epitaxial layer

light shield

nwell photodiode

MOSFET circuitry

2 - 5 μm

light shield

Radiation sensitive pixel readout

Radiation sensitive pixel readout

Technology investment by BNL that can be helpful in solving SOLIC challenges

• Assume that terrorists will use any means to get attention, including radioactive materials

• Develop of new radiation detectors– Gamma spectrometers– Neutron imagers

• Improve interdiction of radioactive materials traffic– Force protection from Radiation Dispersal Devices– Force protection from Improvised Nuclear Devices

Interrogation of containers and trucks

Accelerator

Gamma spectrometer or neutron imager

Container

Target

n,γ

n,γ

Directional Detection and Imaging

• Pinhole camera• Poor sensitivity

FISSION SOURCE

MODERATORPINHOLE

He-3 WIRE CHAMBER

neutron

4. Cadmium-linedcoded aperture camera

Thermal Neutron Imager

G(i,j)

Reconstructing the image from the shadowgram

(-1)

(+1) R(k,l) = N(i, j)G(k + i,l + j)j=1

r

∑i=1

r

∑

N(i,j)

SHADOWDATAN(i,j)

MASK ARRAYG(k,l)

G(i,j)

Reconstructing the image from the shadowgram

(-1)

(+1) R(k,l) = N(i, j)G(k + i,l + j)j=1

r

∑i=1

r

∑

N(i,j)

Actually, use Fast Fourier Transforms

Lab test of imaging capability

Three 10-cm cubes of polyethylene, with two Cf-252 sources embedded(courtesy of A. Caffrey, INL)

20 cm

Neutron image

R = 300 cm, f = 30 cm

Neutron image

R = 300 cm, f = 30 cm

20 cm

Tests in the lab

Photograph Neutron Image

BPE Shielding Wooden wedge

Neutron sourcebehind

paraffin cylinder

Tests in the field

Thermal neutronimage

Spent nuclear fuel storage casks at Idaho National Lab

SOURCE IN TRUNK OF CAR THERMAL NEUTRON IMAGE

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8

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PIXEL INTENSITY

NU

MB

ER O

F PI

XELS

BACKGROUND

SOURCE

PIXEL INTENSITY HISTOGRAM

Count rate as a function of distance

0.001

0.01

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10

100

1000

0.1 1 10 1000.001

0.01

0.1

1

10

100

1000

0.1 1 10 100

corridorcartheory

CO

UN

T R

ATE

(cps

)

DISTANCE (m)

Simple attenuation model for neutron point source in air

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100

1000

10000

100000

1 10 100

r (m)

Neu

tron

flux

Direct ThermalFastTotal scattered

Fast neutron mfp ~ 100 m

Direct thermal neutron mfp ~ 20 m

Scattered

Detectors can be scaled up to increase count rates

20 cm x 140 cm

100 cm x 100 cm

Active interrogation• A pulsed electron accelerator

produces high-energy x-rays (10-MeV) to generate photonuclear reactions

• Nuclear materials will undergo photofission and generate prompt and delayed neutrons

• The delayed neutrons continue to be emitted after each prompt neutron emission

D.R. Norman, J.L. Jones, K.J. Haskell, P. Vanier and L. Forman, IEEE NSS-MIC Conference Record, October 23-29, 2005

Active Interrogation with Imaging

10 MeV electron accelerator

Neutron imagerContainer

n

X-ray continuum

D.R. Norman, J.L. Jones, K.J. Haskell, P. Vanier and L. Forman, IEEE NSS-MIC Conference Record, October, 2005

Image analysis

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12

1 51 101 151 201 251

Relative Neutron Intensity

• Depleted uranium in polyethylene– 6.5-17.5 ms image window– 69k neutrons, mean = 72, σ

= 28

Image 2• Tungsten in polyethylene– 6.5-17.5 ms Image window– 17k neutrons, mean = 122, σ

= 41

Neutron Response for Image 3

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100000

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Time (ms)

Cou

nts

DU PNDDU Bare He-3W PNDW Bare He-3 Imaging Window

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1 51 101 151 201 251

Relative Neutron Intensity

PIXEL INTENSITY HISTOGRAMS

6 σ

• Use time gate to distinguish prompt neutrons from delayed fission

8-element fast neutron double-scatter spectrometer

Experimental data, Fast neutron source centered

Plane spacing = 50 cm, Range = 100 cm

Large area fast-neutron double-scatter directional detector

Area 40 cm x 100 cmModular design is expandable

• Directional detection helps find a neutron source in a uniform background

• There are few naturally occurring neutrons• Ongoing issues

– Detector size – Efficiency– Angular resolution– Uniformity– Gamma rejection– Spectroscopy

CONCLUSIONS

Acknowledgement

The BNL Detector Development and Testing Division is grateful for continuing support from

DOE NA-22, DHS and DTRA