He-3 Free Neutron Detector Applications · neutron signal in WLS material High light collection efficiency Simple, scalable construction, limits will probably be determined by other

symet r i ca . com

He-3 Free Neutron Detector ApplicationsMark Foster, Matthew Da l l imore , Gera int Dermody

A p r i l 1 6 t h 2 0 1 9

P r i v a t e a n d C o n f i d e n t i a l

• Design, manufacture and support of innovative products to detect and identify potential radioact ive threats

• UK based SME founded in 2002

• 50+ staff, 69% hold PhD/MSc/MA/MBA

• Dedicated detector design, a lgorithm, model l ing and hardware research personnel backed up by in -house test faci l i t ies

s y m e t r i c a . c o m

Company Overview

Manufacturing Locations


• US Govt. IDIQ $143m via Smiths Detection over 5 years – Handheld RI ID

• Dutch Customs – Handheld RI IDs, Portals and Mobile Systems

• Finland (STUK) – Handheld RI ID incumbent 4 year contract


Key Wins

• Equatorial portals

• OEM detectors – 100s per year (L3 portals, neutron detectors for Thermo PackEyebackpack)

• International test campaigns

P r i v a t e a n d C o n f i d e n t i a ls y m e t r i c a . c o m

Products & Advantages

Handhelds

MobilesPortals

Portals

Wearables

• Rapid, accurate identif ication of radiological and nuclear threats

• Increased eff iciency with s ignif icantly reduced nuisance alarms

• Combined radiat ion detection and identif ication capabi l i ty

• Reduced cost of ownership by el iminating regular manual cal ibrat ion and maintenance

• Increased security confidence through ease of use, remote diagnostics, and continuous system health report ing

UAV/UGV Integration


Underlying Technology

1 2 / 0 4 / 2 0 1 9 s y m e t r i c a . c o m

WLS BULK PVT + LiF/ZnS detector

Large area possible

High efficiency of conversion of neutron signal in WLS material

High light collection efficiency

Simple, scalable construction, limits will probably be determined by other factors

Compact– ideal for handheld & worn detectors

Low Cost

Flexible configurations

Dark noise

SiPM/MPPC vs PMT:

Robust – micro-phonic free and not affected by magnetic fields

Low power – enables long battery life on portable equipment



1 2 / 0 4 / 2 0 1 9 s y m e t r i c a . c o m


Large area possible




• Readout electronics

• Neutron/gamma d iscr iminat ion by PSD

• Detect ion of pu lse p i le up for accurate dead t ime measurement

• Cont inuous monitor ing of pulse he ight to t rack health long term



1 2 / 0 4 / 2 0 1 9 s y m e t r i c a . c o m


Large area possible




• Performance Metrics:

• Gamma-ray Re ject ion (GRR)

• Gamma Absolute Re ject ion Rat io neutrons ( GARRn)

• Readout eff ic iency (how many captured neutrons are actual ly counted?)

• Sensit iv i ty (very appl icat ion dependant…)


Importance of Scalability

SiPM readout2” PMT readout

10 -> 100 cm2100 -> 1000 cm2 1000+ cm2

Handhelds

Dosimeter

Safeguards

WearablesPortals

Mobiles


Timeline

A p r i l 1 2 , 2 0 1 9 s y m e t r i c a . c o m


NNS2000 Large Area Sensor


• 2.0 cps/ng @ 2m (bare Cf 252 and 5cm thick moderator)

• GRR < 1 in 107 (tested at 100µSv/hr with Cs 137)

• GARRn 1.00 +/- 0.05

• Internal health monitoring

• External blanking input

• 113 x 35 x 13cm (44kg)




Three or four NNS per side(passes ANSI N42.35-2019)

NNS2000 (lightened)in stackable case

with gamma spectrometers(passes ANSI N42.43-2016)

~300 deployed in portals and other systems in:US, Wales, Hong Kong, Netherlands, Colombia, Saudi Arabia




Mobile systems passing ANSI N42.43-2016 neutron detection performance

Three systems deployed by Dutch customs


The relative sensitivity to a range of neutron sources.

Source Relative Sensitivity Error [+/- 2 s]

Cf-252 : Cf-252 1 0.02

Cf-252 / AmBe 1.27 0.03

Cf-252 / PuO 0.88 0.02

AmBe / PuO 0.70 0.02


Relative Sensitivity: NNS2000

ITRAP+10 Test Facility (outdoor)

vertical

The authors would like to thank JRC for providing access to the testing facilities in Ispra and Alice Tomanin, Hamid Tagziria and Paolo Peerani for their support and collaboration.


Blanking Feature


• Blanking electronics

enables use in X-ray

Systems

• Fielded in Smiths &

L3 X-ray Systems

• Data fusion and

display developed

by Symetrica


Neutron “blade”

P r i v i l e g e d a n d C o n f i d e n t i a l

Developed long, s l im prof i le b lade detector s w i th on -board readout and gamma d iscr iminat ion e lect ron ics

6cm (W)x60cm (H)x <0.5cm th ick

<100mW per b lade, 395 g per b lade, TTL output

Enhanced dead-t ime min imizat ion a lgor i thm

GRR: 5 . 1x10 -8 for Cs-137 a t 100msV/hr

Sens i t iv i ty : 44 .4 cps for 5 .21 ng Cf-252 in 5cm HDPE at 2 .5 cm

Readout e f f i c iency : es t imated at 85 . 1%


Neutron Coincidence Counter


• Util ises “blade” neutron detectors with SiPM readout & optimised

for a thin flat sensit ive volume

• First developed in 2014, PoC tested at JRC-Ispra for the He3 Free

Safeguards Workshop

• Full system delivered and tested in 2017

H. Tagziria, M. Foster, M. Schear, D. Ramsden, G. Dermody, B. Pedersen, P. Peerani, P.

Schwalbach, Experimental Assessment of a 6LiF:ZnS(Ag) Prototype Neutron Coincidence

Counter for Safeguards, ESARDA Bulletin No.53, 2015, pg.30


System Description


Physical Specifications HLNCC-II LiFZnS Blade Counter

External Dimensions 73.7 x 34cm (HxDia) 78 x 63 x 63 cm (HxLxW)

Weight 55 kg 170 kg

Sample Cavity Size 40.6 x 17cm (HxDia) 40.6 x 20 x 20cm (HxLxW)

Detectors 18 He-3 tubes at 4 atm 32 LiF/ZnS blades

Detector active length 50.8x2.54 cm (HxDia) 50x 6 x 0.7cm (HxWxD)

• 32 blades in four banks around a sample

cavity

• HDPE posts in the corners increase eff ic iency

without increasing die-away t ime


System Description


Physical Specifications HLNCC-II LiFZnS Blade Counter

External Dimensions 73.7 x 34cm (HxDia) 78 x 63 x 63 cm (HxLxW)

Weight 55 kg 170 kg

Sample Cavity Size 40.6 x 17cm (HxDia) 40.6 x 20 x 20cm (HxLxW)

Detectors 18 He-3 tubes at 4 atm 32 LiF/ZnS blades

Detector active length 50.8x2.54 cm (HxDia) 50x 6 x 0.7cm (HxWxD)

• 32 blades in four banks around a sample

cavity

• HDPE posts in the corners increase eff ic iency

without increasing die-away t ime


Measured Performance


Parameter HLNCC-II LiF:ZnS NCC

Ε abs (%) 16.5 22.5

GW (µs) 64.0 39.6

τ (µs) 43.3 31.2

fd 69.6% 45.1%

FOM 2.51 4.03

FOM2 1.44 1.61

30%

35%

40%

45%

50%

55%

60%

65%

30 40 50 60 70 80

Gat

e Fr

acti

on

Gate width (us)

Doubles Gate Fraction

PD = 12us

PD = 13us

PD = 14us

PD = 15us

• A key parameter to introduce is doubles

gate fraction – fd

• Fraction of true doubles captured in the

R+A gate

• Should be included in the FoM for a more

complete picture

• This system shows a poor fd which is the

limit in its improvement over the HLNCC-II

𝐹𝑜𝑀2 =𝜀 ∙ 𝑓𝑑

𝜏

𝑓𝑑 = e−𝑃𝐷𝜏 (1 − e

−𝐺𝑊𝜏 )


Future Developments


• The NCC described here wi l l be tested with MOX fuel rods in a safeguards exercise at SCK in Belgium for the IPNVD

• We have also designed an annular mult ipl ic ity counter using 32 blades

• ε = 40.3% and τ = 24µs

• FOM = 8 .2

• miniENMC footpr int


Fissile Material Detection



Handheld


Sensitivity GRR GARRn

0.38 cps/ng bare Cf-252 at 25cm0.74 cps/ng mod Cf-252 at 25cm (2 cm

HDPE)3.4 x 10-8 (137Cs)

1.00 at 200μSv/hr (137Cs)


Backpack Form Factor


• HDPE clad Blades

packs

• Fielded in PackEye

Backpack since 2015

• Now fielded in

Symetrica Backpack

and winning MRDS

backpack


ANSI N42.53-2013 Passing Backpack



ANSI N42.53-2013 Passing Backpack


• Detects neutrons moderated by the wearer

• Tested at MTA-EK in Hungary

• Detected >96/100 passes of Cf -252 source

• Fewer than 5 false alarms in 10 hours

symet r i ca . com

Thank youm.foster@symetr ica .com

Documents

He-3 Free Neutron Detector Applications · neutron signal in WLS material High light collection efficiency Simple, scalable construction, limits will probably be determined by other