Morgan Burks, LLNL. Photo: On the way to El Centro Atómico Bariloche, in Patagonia (Argentina) for a reconnaissance trip. 1 Q1135-PPT# author

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1 Morgan Burks, LLNL Photo: On the way to El Centro Atómico Bariloche, in Patagonia (Argentina) for a reconnaissance trip 1

Scientific Sun: solar flares Galactic objects: pulsars, supernova remnants, molecular clouds, hard x-ray sources Extra Galactic objects: quasars, galactic centers,

coincidence Gamma Camera (Anger Camera): hot thallium-201 or technetium-99m source NaI detector with collimator and position sensitive PMT s National Security

2 Scientific Sun: solar flares Galactic objects: pulsars, supernova remnants, molecular clouds, hard x-ray sources Extra Galactic objects: quasars, galactic centers, gamma-ray bursts Medical Positron Emission Tomography (PET) Radioactive tracer emitting positrons Each 511 kev photon detected by scintillator detector in coincidence Gamma Camera (Anger Camera): hot thallium-201 or technetium-99m source NaI detector with collimator and position sensitive PMT s National Security Counter terrorism: finding/locating radioactive materials International Safeguards: verifying facility operation Treaty verification/ Arms control: imaging and/or counting warheads 2

upper array: NE 213A liquid scintillator lower

3 Crab Nebula CGRO flew from 1991 to 2000 Designed for gamma-rays from 20 kev to 30 GeV The Compton telescope consisted of two detector arrays. upper array: NE 213A liquid scintillator lower array: NaI crystals. 1 to 3 MeV gamma ray map from the Compton Telescope on board CGRO) 3

4 RHESSI Ramaty High Energy Spectroscopic Solar Imager In Earth orbit since Feb Images gamma-rays from 3 kev to 20 MeV Images Sun to understand particle acceleration and energy release in solar flares. Consists of 9 Ge coax detectors Uses rotating modulation collimators to form the image

5 Fourier-transform imaging 9 rotating modulation collimators (grid pairs) Field of View: Full Sun (~1 degree) Angular Resolution 2 arcseconds to 100 kev 7 arcseconds to 400 kev 36 arcseconds above 1 MeV Source sizes that can be imaged ~2 arcseconds to ~180 arcseconds Instrument Non-position sensitive Ge detector Complex collimator required

back to back 511 kev photons The photon are detected in coincidence Image reconstruction

6 Used in nuclear medicine to measure metabolic activity in terms of regional glucose uptake Uses radioactive tracer that emits positrons Positrons annihilate locally and give off two back to back 511 kev photons The photon are detected in coincidence Image reconstruction techniques are used to form a 3D picture of the region of interest Often used in conjunction with a CT scan 6

A multi-hole collimator limits the field of view to a small window The

7 Uses radio tracers such as thallium-201 or technecium-99m Gamma-rays are detected by an array of scintillators / PMT s. A multi-hole collimator limits the field of view to a small window The system is then scanned across the region of interest High resolution can be achieved at the price of high dose 7

8 Germanium Low energy <300 kev Photoelectric effect dominant collimator based imaging Coded aperture RMC Fourier Transform imagers variations Medium energy 300 kev to 10 MeV Compton effect dominates Compton imaging High energy > 10 MeV Pair production dominates Pair telescopes

1. Measurement: The position and energy of each gamma-ray interaction must be measured. 2. Tracking: The order of interactions must be determined using various physical constraints 3.

9 1. Measurement: The position and energy of each gamma-ray interaction must be measured. 2. Tracking: The order of interactions must be determined using various physical constraints 3. Compton reconstruction: The initial scatter angle is then determined by the Compton formula 4. Image reconstruction: The image is then built event by event The Compton scattering formula gives : cos r1 r 12 r2 E r3 1 E 1 2 E1m0 c E E E E r4 E source 1 1 E2 E3 E4

latitude + - + - latitude Germanium-Based Compton Imager 1.

Measure position and energy of y2 each interaction. y1 2.

(1 cos ) x1 x2 3. Each -ray resolves to a ring on the sky map. 4.

10 latitude latitude Germanium-Based Compton Imager 1. ray interacts at multiple locations in the detector. Measure position and energy of y2 each interaction. y1 2. Scatter angle given by Compton Scatter equation E ' E 1 2 m0c E (1 cos ) x1 x2 3. Each -ray resolves to a ring on the sky map. 4. Many -rays form an image Arthur H. Compton Measured point source 1408 kev ( 152 Eu) Resolution ~1.2 0 image1 longitude image1 longitude

image5 ~0 deg (on-axis) 60 deg 359 179 image2 i j image5 30 deg N i 0 j 0 359 179 image1 image5

11 image5 ~0 deg (on-axis) 60 deg image2 i j image5 30 deg N i 0 j image1 image5 i j i 0 j 0 75 deg mage2 i j mage1 i j image5 45 deg image5 60 deg (in 3-D for comparison) image5

12 Imaging Resolution (degrees) 1408 kev (0 deg to 60 deg) 30 0 ARM (Angular Resolution Metric) = Full-Width ARM vs. Energy Half-Power (at 30 (fwhp) degrees) image image image Simulated Measured image1 image Energy (kev) Eu152 source was used to measure the point spread function vs. energy and angle Excellent angular resolution was achieved across broad energy range.

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500 Energy Spectrum 22 Na 400 300 200 100 511 kev 662 kev?

1400 137 Cs 22 0 Na 0 Image: 511 kev sumimage Image: 662 kev

16 500 Energy Spectrum 22 Na kev 662 kev? Resulting spectrum 1274 kev Cs 22 0 Na 0 Image: 511 kev sumimage Image: 662 kev (shown in 3-D) 360 o Compton imager looking at various sources image2

row Simulated Ideal Imaging Response 5 10 1.

17 row Simulated Ideal Imaging Response Mask pattern and position sensitive detector Coded Aperture Imagers Good for point sources Not effective for extended sources Best for gammas rays < 300 kev Requires position sensitive detector Limited Field of View 2. Detector after point source exposure col first_pt_source_no_back 3. De-convolved point source image

18 The gamma-ray imaging spectrometer uses a coded aperture and a multi-element position-sensitive detector Gamma-ray camera imaging the Peacekeeper missile Gamma-ray image of Peacekeeper missile clearly shows ten warheads

Research funded by the DOE Office of Nonproliferation and International

Community ABACC: Brazilian-Argentine Agency for Accounting and Control of

Laboratory Lawrence Berkeley National Laboratory Purpose To demonstrate a use

include Design Information Verification (DIV) Materials accountancy Hold-up

19 Research funded by the DOE Office of Nonproliferation and International Security (NA-24) Collaboration includes Euratom: European Atomic Energy Community ABACC: Brazilian-Argentine Agency for Accounting and Control of Nuclear Materials Oakridge National Laboratory Lawrence Livermore National Laboratory Lawrence Berkeley National Laboratory Purpose To demonstrate a use for gamma-ray imaging in International Safeguards applications Applications include Design Information Verification (DIV) Materials accountancy Hold-up location and quantification Decontamination and Decommission PFEP (Pilot Fuel Enrichment Plant) Natanz, Iran

Dual Planar Compton Imager Design: dual thin germanium planar detectors with 3 mm voxels Readout:

demonstrated, trying for higher ratio) Spectral resolution: 1.

5 o ) Power Consumption: 15 watts (plus laptop power) Cooling: Prototype uses liquid nitrogen.

20 Dual Planar Compton Imager Design: dual thin germanium planar detectors with 3 mm voxels Readout: Custom 32-channel digitizer; USB to Laptop Multiplexing: In progress (5 to 1 multiplexing demonstrated, trying for higher ratio) Spectral resolution: 1.8 kev Angular resolution: 7 o (target = 3.5 o ) Power Consumption: 15 watts (plus laptop power) Cooling: Prototype uses liquid nitrogen. Next generation will be mechanically cooled Cost: $150k Power Controller Imager Laptop for imaging and analysis Electronic Readout Imaging system designed and built in collaboration with PHDs Co., Knoxville TN

mm Range: up to 79 meters Data rate: 1 Megapixels / second

21 Gamma-ray imaging is greatly aided by addition of 3D LIDAR Zoller + Froehlich 5006 laser scanner Resolution: 1 to 7 mm Range: up to 79 meters Data rate: 1 Megapixels / second FOV: 360 o horizontal 310 o vertical Scan time: few minutes

voxel size A 2D gamma-ray image is backprojected onto the range map snapshot of the 3D model - top view

22 A 2D gamma-ray image is backprojected onto the range map snapshot of the 3D model - side view; 3D Backprojected image: 3000 total number of photons; 3 CCI positions; voxel elements; 5x5x5cm 3 voxel size A 2D gamma-ray image is backprojected onto the range map snapshot of the 3D model - top view 3D Reconstructed image: 3000 total number of photons; 3 CCI positions; voxel elements; 5x5x5cm 3 voxel size

feet # enrichment stages: 1760 Peak Power

23 Only uranium diffusion plant in U.S. In operation since 1952 Began by making feedstock for weapons Now makes LEU for commercial power Process Buildings: 1100 x 970 feet # enrichment stages: 1760 Peak Power Consumption: >2 GW # of control instruments: 85,000 Miles of Process Piping: ~400 23

24 Buildup in restricted pipe Many pipes hidden behind heat shielding. However, they can still be measured and the contamination located with the gamma-ray imager Transfer / Withdrawal stations Where product is transferred from to and from containers for shipment: This is an obvious place where one would want to monitor the process Gas flow through pipes Measuring absolute enrichment is hard with gamma-ray spectroscopy (or imaging) alone. It is also necessary to know the gas density. However, relative enrichment can be measured (or change detection). Contaminated equipment Monitor equipment for storage or decontamination and decommission. 24

Purpose of measurement campaign: 1. Test instrumentation in a real-world environment 2. Demonstrate relevance to International Safeguards applications Challenges 1.

25 Purpose of measurement campaign: 1. Test instrumentation in a real-world environment 2. Demonstrate relevance to International Safeguards applications Challenges 1. Extremely hot (>115 o F) 2. Restricted spaces and physical barriers 3. Limited facilities (electrical, LN2 etc.) 4. Dust 5. Radioactive contamination 6. Significant access restrictions 25

26 Imaging known neptunium deposit 3D-LIDAR Compton Imager Coded Aperture Imager 3D LIDAR makes 360 degree laser image of the room Coded aperture has 45 degree field of view and must be aimed in the right direction Compton imager has 4-pi field of view 26

Measured Spectrum (enriched uranium flow pipe w/ contamination) 1 10 4 5500 186keV 235 U 300, 312, 340, 398, 415 kev 237 Np(

27 Measured Spectrum (enriched uranium flow pipe w/ contamination) keV 235 U 300, 312, 340, 398, 415 kev 237 Np( 233 Pa) kev 238 U( 234m Pa) h1 i i Energy (kev)

28 Compton imager localized hot spot and identified it as Np-237

Gamma-Spectroscopy (and imaging) location of

Contaminated pipe 186keV 235 U 766, 1001 kev 238

120 Energy (kev) Spectroscopy clearly identifies

Gamma image not shown due to proprietary design

29 Gamma-Spectroscopy (and imaging) location of contaminated piping Spectrum from Contaminated pipe 186keV 235 U 766, 1001 kev 238 U( 234m Pa) Energy (kev) Spectroscopy clearly identifies contamination of U-235 and U-238. Gamma image not shown due to proprietary design concerns on piping; however, image was easily able to localize contamination 29

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31 Coded Aperture Image of low enriched UF 6 flowing through process pipe (Klaus Ziock et. al, ORNL) fiducial markers allow alignment of visual, LIDAR and gamma image Image based on 186 kev lines from U-235 Acquisition time: ~ hour 31

32 311 kev distribution 32

33 33

First field demonstration of a Compton-based gamma-ray imager Demonstrated ease of portability/use in a real-world environment Prototype efficiency was low but still took valuable measurements Next

34 First field demonstration of a Compton-based gamma-ray imager Demonstrated ease of portability/use in a real-world environment Prototype efficiency was low but still took valuable measurements Next steps: looking at arms control applications (NA-22 funding) Building an upgraded instrument Increased sensitivity Increased portability Mechanical cooling Built in panoramic camera This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA Lawrence Livermore National Security, LLC 34

35 35

1. Gamma-ray imaging is a powerful tool for locating

A combination of measurements and measurements were

36 1. Gamma-ray imaging is a powerful tool for locating and identifying radioactive materials 2. This technology is advancing quickly 3. Has potential application to Safeguards problems such as DIV 4. NA-24 funded international collaboration 5. A combination of measurements and measurements were used Process test bench for reprocessing study in the Nuclear Fuel Cycle Safety Engineering Research Facility (NUCEF) -JAEA

1.4 MeV High imaging resolution Extended and point sources Rotation Modulation Collimators Range: 92 million

37 Coded Aperture Range: ~100 meters 1-D and 2-D imaging Modest field of view (45 o ) Have built 16 cm 2 to 8000 cm 2 systems Typically <300 kev Point sources Compton Range: 10 s of meters 2-D, 3-D & 4- imaging Up to 1.4 MeV High imaging resolution Extended and point sources Rotation Modulation Collimators Range: 92 million miles! Requires lots of signal! No terrestrial systems deployed (to my knowledge) Narrow FOV Up to 1 MeV y x z

39 Counts 1. Locate source 2. Image source: Differentiate extended vs point-like sources 3. Differentiate complex mixed sources 4. Increased sensitivity: separate signal from background Background varies with location and time 1x10 5 1x10 4 1x10 3 1x10 2 1x Energy (kev) High-resolution spectrum of typical background radiation Natural uranium (granite, pottery) and depleted uranium (ammunition, counterweights) are common Both 232 U, present in most but not all HEU, and background 232 Th decay to 208 Tl emit gamma rays at 2615 kev Medical isotopes can walk around!

Compact Compton Imager CCI-1 Compact Compton Imager

st generation DAQ/ cart Highlights: 2D Gamma-ray imaging

area Demonstration of stand-off 3D imaging Demonstration

two cryostats/ 2 nd generation DAQ/ no cart Improvements

Count rate capability (x100 increase, as compared with

40 Compact Compton Imager CCI-1 Compact Compton Imager CCI-2 1 Ge plus 1 Si DSSD detectors in two cryostats/ 1 st generation DAQ/ cart Highlights: 2D Gamma-ray imaging Demonstration of spectroscopy from a limited spatial area Demonstration of stand-off 3D imaging Demonstration of near-field 3D imaging 2 Ge +2 Si DSSD detectors in two cryostats/ 2 nd generation DAQ/ no cart Improvements in : Sensitivity (x10 increase, as compared with CCI-1) Count rate capability (x100 increase, as compared with CCI- 1, now 10kHz) Real-time imaging capability demonstrated recently.

A NEW GENERATION OF GAMMA-RAY TELESCOPE

A NEW GENERATION OF GAMMA-RAY TELESCOPE Aleksandar GOSTOJIĆ CSNSM, Orsay, France 11 th Russbach School on Nuclear Astrophysics, March 2014. Introduction: Gamma-ray instruments GROUND BASED: ENERGY HIGHER