1 m z

TWO-COLOR NEUTRON DETECTION FOR ZERO-KNOWLEDGE NUCLEAR WARHEAD VERIFICATION

Yan Jie and Alexander Glaser56th INMM Meeting, Indian Wells, California, July 2015

Revision 1

P R E V E N T I N G T H E E X C H A N G E O F S E N S I T I V E I N F O R M AT I O N

Trusted Information Barrier Protocol

Interactive Zero-Knowledge Protocol

Measure sensitive Information Never measure sensitive information

Single-bit observation More complex observation

Hard to authenticate and certify Easier to authenticate and certify

(S. Philippe, B. Barak and A. Glaser, “Designing Protocols for Nuclear Warhead Verification,” this conference)

Yan Jie and A. Glaser, INMM, July 2015

OUR GENERAL APPROACH

3

TEMPLATE-MATCHING (using active neutron interrogation)More difficult to implement than attribute approach, but also more robust against important diversion scenarios

INTERACTIVE ZERO-KNOWLEDGE PROTOCOLCan prove that a statement is true without revealing why it is true In contrast to “traditional approaches,” no requirement for trusted information barrier

NON-ELECTRONIC DETECTORSElectronic hardware and sostware used for detectors and, especially, for information barriers are hard to certify and authenticate

Technologies based on “physical” detection may offer important advantages

Generally requires “golden warhead” to generate template (reference signature)

14 MeV Neutron source (Thermo Scientific P 385)

Detector array

Collimator

Collimator slotTest object

“ONE-COLOR” RADIOGRAPHY

(coming up next)

P R O O F T H AT T W O R A D I O G R A P H S A R E I D E N T I C A L

+ =

R A D I O G R A P H I T E M A

C O M P L E M E N T I T E M A F L AT B A C K G R O U N D

+ =

R A D I O G R A P H I T E M B

C O M P L E M E N T I T E M A F L AT B A C K G R O U N D

I T E M B I S E Q U A L T O I T E M A

+ =

R A D I O G R A P H I T E M A

C O M P L E M E N T I T E M A F L AT B A C K G R O U N D

+ =

R A D I O G R A P H I T E M B

C O M P L E M E N T I T E M A R E S I D U A L I M A G E

I T E M B I S N O T E Q U A L T O I T E M A

P R O O F T H AT T W O R A D I O G R A P H S A R E I D E N T I C A L

Yan Jie and A. Glaser, INMM, July 2015

ZERO-KNOWLEDGE VERIFICATION

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Simulated data from MCNP calculations; neutron detection energies > 10 MeV; N(max) = 5,000 A. Glaser, B. Barak, R. J. Goldston, “A Zero-knowledge Protocol for Nuclear Warhead Verification,” Nature, 510, 26 June 2014, 497–502

Valid item Invalid item

(Tungsten rings replaced by lead rings)

RADIOGRAPHY WITH 14 MeV NEUTRONS

Yan Jie and A. Glaser, INMM, July 2015

FISSION CROSS SECTIONS

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Pu-239Pu-240U-235

U-238

OF THE MAIN URANIUM AND PLUTONIUM ISOTOPES

Yan Jie and A. Glaser, INMM, July 2015

FISSION CROSS SECTIONS

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Source: Evaluated Nuclear Data File (ENDF), www-nds.iaea.org/exfor/endf.htm R. J. Goldston et al., “Zero-knowledge Warhead Verification: System Requirements and Detector Technologies,” 55th INMM Meeting, 2014

Pu-239

Pu-240

U-235

U-238

Pu-239Pu-240U-235

U-238

OF THE MAIN URANIUM AND PLUTONIUM ISOTOPES

Idea: Let’s interrogate with neutrons in the 300-keV range and look for fission neutrons (> 1 MeV)

“TWO-COLOR” NEUTRON SETUP

Yan Jie and A. Glaser, INMM, July 2015

POSSIBLE IMPLEMENTATIONS

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TEST ITEM

14 MeV SOURCE

Dn > 10 MeV

TRANSMISSION RADIOGRAPH

TEST ITEM

14 MeV SOURCE

Dn > 500 keV D n

> 5

00 k

eV

FISSION SIGNATURE

TEST ITEM

Dn > 500 keV D n

> 5

00 k

eV

300 keV SOURCE

Dn > 500 keV

FISSION SIGNATURE

“ONE-COLOR” AND “TWO-COLOR” SETUPS FOR ACTIVE NEUTRON INTERROGATION

Yan Jie and A. Glaser, INMM, July 2015

POSSIBLE IMPLEMENTATIONS

12

TEST ITEM

14 MeV SOURCE

Dn > 10 MeV

TRANSMISSION RADIOGRAPH

TEST ITEM

14 MeV SOURCE

Dn > 500 keV D n

> 5

00 k

eV

FISSION SIGNATURE

TEST ITEM

Dn > 500 keV

(Dn >150 keV)

300 keV SOURCE

FISSION SIGNATURE (AND TRANSMISSION RADIOGRAPH)

TEST ITEM

Dn > 500 keV D n

> 5

00 k

eVFISSION SIGNATURE

14 MeV SOURCE

Dn > 10 MeV

300 keV SOURCE

Dn > 500 keV

(AND TRANSMISSION RADIOGRAPH)

“ONE-COLOR” AND “TWO-COLOR” SETUPS FOR ACTIVE NEUTRON INTERROGATION

Yan Jie and A. Glaser, INMM, July 2015 13

D. Chichester

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Fig. 5 Total neutron yield curves for several reactions. (The DD and DT data for this plot is derived from reference 24 and refers to a fully loaded titanium target with deuterons accelerated into TiD2 for the 2H(d,n)3He reaction and deuterons accelerated into TiT2 for the 3H(d,n)4He. The solid plots refer to 100% atomic beams, except for the 9Be(γ,n)8Be reaction, while the two dashed plots refer to 100% molecular ion beams.)[24,25]

2.1.1 2H + 2H → 3He + n

Using the DD fusion reaction is a straightforward and often used technique for neutron production with particle accelerators. The reaction is exothermic and its cross section yields a useful neutron production rate with accelerating energies of O(100) keV and modest beam currents of O(100) μA. Neutrons from this reaction start at ~2.5 MeV, they are roughly monoenergetic at lower accelerating energies but less so at higher energies, as shown in Fig. 6. The low Q value for the reaction results in a forward-directed anisotropic yield even at low accelerating potentials, with the relative yield from 0° to 90° decreasing by 4× for an accelerating potential 0.5 MeV.[19] The low yield of this reaction compared with the others described here limits its use in many

David L. Chichester, Production and Applications of Neutrons Using Particle Accelerators INL/EXT-09-17312, Idaho National Laboratory, November 2009

A STRONG 300-keV NEUTRON SOURCETOTAL NEUTRON YIELD CURVES FOR SELECTED (THRESHOLD) REACTIONS

OPEN-SOURCE MONTE CARLO SIMULATIONS

SimLiT + GEANT 4

Yan Jie and A. Glaser, INMM, July 2015

MODELING APPROACH

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SimLiT

Dedicated Monte Carlo code to simulate neutrons from 7Li(p,n) reaction

Ability to couple to Geant 4

Open source (designed as a C++ class)

Geant 4

A Monte Carlo simulation toolkit for the simulation of the passage of particles through matter; used in many scientific fields

SIMLIT AND GEANT 4

Open source (C++)

(geant4.cern.ch)

(shrek.phys.huji.ac.il/SimLiT)

Yan Jie and A. Glaser, INMM, July 2015

SIMULATED p-Li NEUTRON SOURCE

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SPECTRUM CAN BE TAILORED BY ADJUSTING THE INCIDENT PROTON ENERGY AND THE THICKNESS OF THE LITHIUM TARGET

Yan Jie and A. Glaser, INMM, July 2015

SIMPLIFIED EXPERIMENTAL SETUP

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NEUTRON SOURCE, TEST ITEM, AND DETECTOR ARRAY

1 m z

p-Li neutron source

Test item

Neutron detector array (25 x 25)

100 cm 50 cm

Yan Jie and A. Glaser, INMM, July 2015

NOTIONAL TEST ITEMS

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Based on: Steve Fetter, Valery A. Frolov, Marvin Miller, Robert Mozley, Oleg F. Prilutsky, Stanislav N. Rodionov, Roald Z. Sagdeev “Detecting nuclear warheads,” Science & Global Security, 1 (3–4), 1990, pp. 225–253

Reference item 14.0 cm OD

12 kg of HEU; 93% U-235

Modified isotopics

Modified diameter 15.0 cm OD

(same mass)

Reference item 10.0 cm OD

4 kg of WPu; 93% Pu-239

Modified isotopics

Modified diameter 11.0 cm OD

(same mass)

Fetter et al.’s Uranium Item (12 kg weapon-grade HEU)

Fetter et al.’s Plutonium Item (4 kg weapon-grade Pu)

RESULTS

Yan Jie and A. Glaser, INMM, July 2015

300-keV DRIVEN FISSION SIGNATURES

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Detectors Index0 5 10 15 20 25

Det

ecto

rs In

dex

0

5

10

15

20

25

Valid

Detectors Index0 5 10 15 20 25

Det

ecto

rs In

dex

0

5

10

15

20

25

Invalid (75% U-235)

Detectors Index0 5 10 15 20 25

Det

ecto

rs In

dex

0

5

10

15

20

25

Invalid (85% U-235)

Detectors Index0 5 10 15 20 25

Det

ecto

rs In

dex

0

5

10

15

20

25

Invalid (Same mass, Larger)

Bubble Counts (with Preload)4400 4600 4800 5000 5200 5400 5600

Det

ecto

rs

0

20

40

60

80

100

120TemplateValid

Bubble Counts (with Preload)4400 4600 4800 5000 5200 5400 5600

Det

ecto

rs

0

20

40

60

80

100

120Template75% U235

Bubble Counts (with Preload)4400 4600 4800 5000 5200 5400 5600

Det

ecto

rs

0

20

40

60

80

100

120Template85% U235

Bubble Counts (with Preload)4400 4600 4800 5000 5200 5400 5600

Det

ecto

rs

0

20

40

60

80

100

120Template

Same Mass, Larger

Small deviation from Nmax Significant deviation from Nmax (1.5, 2.0, 2.5, 3 Sigma)

Invalid item (75% U-235)

Detector index

Bubble count distribution

Num

ber

of

det

ecto

rsD

etec

tor

index

Valid item (93% U-235)

Detector index

Bubble count distribution

Num

ber

of

det

ecto

rsD

etec

tor

index

Invalid item (85% U-235)

Detector index

Bubble count distribution

Num

ber

of

det

ecto

rsD

etec

tor

index

Yan Jie and A. Glaser, INMM, July 2015

300-keV DRIVEN FISSION SIGNATURES

21

Valid item (93% U-235)

Detector index

Bubble count distribution

Num

ber

of

det

ecto

rsD

etec

tor

index

Invalid item (larger diameter)

Detector index

Bubble count distribution

Num

ber

of

det

ecto

rsD

etec

tor

index

Detectors Index0 5 10 15 20 25

Det

ecto

rs In

dex

0

5

10

15

20

25

Valid

Detectors Index0 5 10 15 20 25

Det

ecto

rs In

dex

0

5

10

15

20

25

Invalid (75% U-235)

Detectors Index0 5 10 15 20 25

Det

ecto

rs In

dex

0

5

10

15

20

25

Invalid (85% U-235)

Detectors Index0 5 10 15 20 25

Det

ecto

rs In

dex

0

5

10

15

20

25

Invalid (Same mass, Larger)

Bubble Counts (with Preload)4400 4600 4800 5000 5200 5400 5600

Det

ecto

rs

0

20

40

60

80

100

120TemplateValid

Bubble Counts (with Preload)4400 4600 4800 5000 5200 5400 5600

Det

ecto

rs

0

20

40

60

80

100

120Template75% U235

Bubble Counts (with Preload)4400 4600 4800 5000 5200 5400 5600

Det

ecto

rs

0

20

40

60

80

100

120Template85% U235

Bubble Counts (with Preload)4400 4600 4800 5000 5200 5400 5600

Det

ecto

rs

0

20

40

60

80

100

120Template

Same Mass, Larger

Small deviation from Nmax Significant deviation from Nmax (1.5, 2.0, 2.5, 3 Sigma)

Yan Jie and A. Glaser, INMM, July 2015

“TRANSMISSION RADIOGRAPH”

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Detectors Index0 5 10 15 20 25

Det

ecto

rs In

dex

0

5

10

15

20

25

Valid

Detectors Index0 5 10 15 20 25

Det

ecto

rs In

dex

0

5

10

15

20

25

Invalid (75% U-235)

Detectors Index0 5 10 15 20 25

Det

ecto

rs In

dex

0

5

10

15

20

25

Invalid (85% U-235)

Detectors Index0 5 10 15 20 25

Det

ecto

rs In

dex

0

5

10

15

20

25

Invalid (Same mass, Larger)

Bubble Counts (with Preload)4400 4600 4800 5000 5200 5400 5600

Det

ecto

rs

0

20

40

60

80

100

120TemplateValid

Bubble Counts (with Preload)4400 4600 4800 5000 5200 5400 5600

Det

ecto

rs

0

20

40

60

80

100

120Template75% U235

Bubble Counts (with Preload)4400 4600 4800 5000 5200 5400 5600

Det

ecto

rs

0

20

40

60

80

100

120Template85% U235

Bubble Counts (with Preload)4400 4600 4800 5000 5200 5400 5600

Det

ecto

rs

0

20

40

60

80

100

120Template

Same Mass, Larger

Small deviation from Nmax Significant deviation from Nmax (1.5, 2.0, 2.5, 3 Sigma)

Valid item (93% U-235)

Detector index

Bubble count distribution

Num

ber

of

det

ecto

rsD

etec

tor

index

Invalid item (75% U-235)

Detector index

Bubble count distribution

Num

ber

of

det

ecto

rsD

etec

tor

index

Detector index

Bubble count distribution

Num

ber

of

det

ecto

rsD

etec

tor

index

Invalid item (larger diameter)

Yan Jie and A. Glaser, INMM, July 2015

ASSESSING THE RESULTS

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USING THE KOLMOGOROV-SMIRNOV STATISTICAL TEST AS A PASS/FAIL CRITERION

75% U-235 0.872 0

85% U-235 0.986 0

Larger diameter 3.738E–05 0

59% Pu-239 0.822 0

75% Pu-239 0.999 0

Larger diameter 0.112 0

Radiograph Fission signature

Valid item 0.988 0.987

Radiograph Fission signature

Valid item 0.998 0.986

Uranium Item Plutonium Item

As expected, radiography (here: using 300-keV neutrons) is not very sensitive to isotopic changes Fission signature is very clear for uranium and plutonium items

Yan Jie and A. Glaser, INMM, July 2015

CONCLUSION AND OUTLOOK

24

“ONE-COLOR” SETUP

Distinguishing isotopic differences can be more challenging because relevant 14-MeV fission cross sections can be similar for some elements (esp. for Pu-239 vs Pu-240)

“TWO-COLOR” SETUPFission signatures triggered by ~ 300-keV neutrons are extremely sensitive to isotopic differences (and also to differences in geometry)

Needed for experimental demonstration: Intense 2-MeV proton source

Neutron transmission radiography using high-energy (14 MeV) neutrons is effective in detecting geometric and elemental differences

Combine with 14-MeV (and ~150-keV) transmission radiography