Development of a counting-type neutron imaging detector for energy-resolved imaging at J-PARC/MLFJoe Parker CROSS-Tokai BL22 Group

1 J-PARC 13 October 2016

RADEN/BL22 and µNID development membersJAEA/J-PARC Center Takenao Shinohara

Tetsuya Kai Kenichi Oikawa (BL10) Masahide Harada (BL10) Takeshi Nakatani Mariko Segawa Kosuke Hiroi Yuhua Su

CROSS-Tokai Hirotoshi Hayashida

Joe Parker (µNID Lead Developer) Yoshihiro Matsumoto Shuoyuan Zhang

Nagoya University Yoshiaki Kiyanagi

RADEN/BL22 – Neutron imaging instrument at the MLF

•  World-class, pioneering instrument for pulsed-neutron imaging

•  Leading facility for conventional radiography in Japan

•  Commissioning from Nov. 2014, user program from April 2015

World’s first instrument dedicated to energy-resolved neutron imaging using pulsed neutrons!

First images from RADEN (7 Nov 2014)

Energy-resolved neutron imaging•  Energy-dependence

quantitative information on macroscopic distribution of microscopic quantities

•  Pulsed neutrons wide energy range, accurate energy determination by time-of-flight

•  Requires detectors with:

•  Spatial resolution < 1 mm

•  Time resolution < 1 µs

•  Count rate > 1 Mcps

•  Strong background rejection

Energy-dependent neutron transmission

EnergymeV 1 keV

Wavelength10 10-2

Resonance absorption

Bragg-edge, Magnetic imaging

Moderator

Bulk shield

ShutterOptical Devices

Experimental Space

1st Detector position

2nd Detector position

13m

5m

Large load sample stage

Optical benchMedium sample stage

0m 8m 14m 27m 31m18m 23m

Conventional radiography/pulsed-neutron imaging

Large beam size (up to 30x30 cm2)

High flux (2.6x107 n/s/cm2 @ <0.5eV) Variable L/D (up to 7500)

Wide bandwidth (~9 , / < 0.2%) Large experimental area

Properties of RADEN

RADEN/BL22 – Neutron imaging instrument at the MLF

RADEN computer system

•  Computer control of beam line components, sample stages, and detectors using IROHA2 (automated measurements)

•  Large data storage capacity (24TB SSD primary, 100TB secondary)

•  Fibre channel network (8 Gb/s) for fast data transfer

•  GPGPU cluster (12 CPUs, 24 GPGPUs) for data analysis

Detectors available at RADENCamera type Counting type

Andor iKon-L -  Cooled CCD -  300µm -  No TOF -  Automated

system for CT

Neutron Color I.I. -  High-resolution

(200 µm) -  High-speed (10k,

30k, 100k fps)

µNID -  Micro-pattern -  3He (18% eff.) -  FOV: 10 × 10 cm2

-  x=0.3mm, t=0.6µs, < 1 Mcps

nGEM -  Micro-pattern w/ 10B (10% eff.) -  FOV: 10 × 10 cm2

-  x=1mm, t=15ns, < 1 Mcps

LiTA12

-  Li-glass scint. (40% eff.) -  FOV: 5 × 5 cm2

-  x=3mm, t=40ns,6 Mcps

0.1

1

10

100

0.01 0.1 1 10

Co

unt r

ate

(M

cp

s)

Spatial resolution (mm)

µNID nGEM

LiTA12

Current performance of counting-type detectors at RADEN

µPIC-based Neutron Imaging Detector (µNID)

µPIC-based neutron imaging detector (µNID)

9.0

cm

32.8 cm

400 µm

X (strips)0 10 20 30 40 50 60

Relat

ive cl

ock p

ulse

05

101520253035404550

Entries 28Entries 28Position

X (strips)0 10 20 30 40 50 60Ti

me-

abov

e-th

resh

old

(clo

cks)

0

5

10

15

20

25

30Energy DepositionTOT for proton-triton track

Proton Triton

Neutron

Digital encoder with time-over-threshold (TOT)

ThresholdµPIC

Discriminator

Time-above-threshold (∝ energy dep.)

neutron proton

triton

3He

•  3-dimensional tracking of decay pattern

•  Energy via time-over-threshold (TOT)

•  Compact ASIC+FPGA data encoder

→  Good spatial resolution, strong background rejection, high data rates possible

Neutron detection via 3He

Track length ~8 mm in gas

E

µPIC

µPIC-based neutron imaging detector (µNID)

•  FPGA-based data encoders •  FPGA-based DAQ controller •  Data transfer via Ethernet

EncodersDAQ PC

SiTCP

EncodersµPIC

Control box DAQ controller system monitor DC power

External timing signals

Vessel pressure

Ethernet

GbE × 4

±2.5V, +3.3V

Ambient temperature

Network

DAQ control

Monitoring

Power

Add 10GbE hub to reduce cables

Sensor power

µNID performance

Image data taken at NOBORU in Feb. 2011

Distance from interaction point (mm)-2 0 4 8Ti

me-

over

-thre

shol

d (n

s)

0

50

100

150

200

250

62

Template for fit

Measured TOT distribution

Proton Triton

•  Strong gamma rejection using TOT information

•  Template fit for position analysis

Avg. time (clocks)0 100 200 300 400 500

Coun

ts/h

r/3.75

cloc

ks0

1

2

3

4

5

6

7

Track-length cut

Avg. time (clocks)0 100 200 300 400 500

Coun

ts/h

r/3.75

cloc

ks

0

0.5

1

1.5

2

2.5

3

3.5

Track length and PID > 2

137Cs No source

‘Energy’ cut

Neutrons

γ’s

Total TOT (clocks)

µNID performance characteristics

Area 10 x 10 cm2

Spatial res. 0.3 mm

Time res. 0.6 µs

TOF/TOF < 0.07% @18m

-sensitivity < 10-12

Efficiency Up to 26%

Count rate 0.6 Mcps

Development of µNID•  Objectives:

•  Improve count rate and spatial resolution

•  Improve data analysis; reduce processing time

•  Integration into RADEN control system

•  Count rate •  Throughput of data encoder modules

•  Drift velocity, stopping power of filling gas

•  Readout geometry

•  Spatial resolution •  Electron diffusion, stopping power of filling gas

•  Readout strip pitch

•  Improvement of count rate and data analysis is most pressing

Data encoder•  FPGA-based encoder modules

•  CMOS ASICS

•  Spartan6 FPGA

•  Ethernet transfer (SiTCP)

•  128 ch/encoder (4 encoders total)

•  Original encoder throughput limited by 100BASE-T Ethernet transfer

•  Upgrades

•  Gigabit Ethernet PHY (1st revision)

•  On-board DDR3 memory (2nd revision, not yet tested)

22 cm FPGA

CMOS ASICS

GbE

DD

R3 m

em

ory

Originally developed by Kyoto U. and KEK (Open-it)

Gas optimization•  Change to CF4-based mixture

•  Increased drift velocity (count rate) •  Decreased electron diffusion (spatial resolution) •  Increased stopping power (both)

Previous gas New gas

Mixture Ar-C2H6-3He (67:7:30 @ 2atm)

CF4-iC4H10-3He (45:5:50 @ 2atm)

Drift velocity 23 µm/ns 58 µm/ns

Diffusion 275 µm/cm1/2 80 µm/cm1/2

Efficiency @25.3meV 18% 26%

Proton-triton track length 8 mm 5 mm

Gas characteristics simulated with MAGBOLTZ, GEANT4

Rate testing at RADEN

•  Control incident intensity using B4C slits

•  Testing of

•  rate capacity of hardware

•  rate linearity of detector

Detector

B4C slits

Neutron beam

Rate testing at RADEN•  Test of revised encoders

with GbE

•  Ar-Ethane gas mixture

•  Compared with original encoder

•  Rate capacity increased by more than factor of 6

•  Mostly linear up to more than 3 Mcps

0

1

2

3

4

5

0 500 1000 1500 2000 2500

Co

unt r

ate

(M

cp

s)

Slit area (mm2)

Neutron rates vs slit area

GbE

100Mbps

Rate testing at RADEN•  Test of CF4-based gas

mixture

•  Encoders with GbE

•  Rate capacity over 8 Mcps

•  Nearly factor of 2 increase over Ar-based gas mixture

0

2

4

6

8

10

0 1000 2000 3000 4000

Co

unt r

ate

(M

cp

s)

Slit area (mm2)

Neutron rates vs slit area

Ar-C2H6

CF4-iC4H10

20 30 40 50 60 70

0.55

0.6

0.65

0.7

0.75

0.8

0.85

0.9

0.95

Sample

Spatial resolution with CF4

•  Image of Gd test pattern •  L/D: 5000 •  Exposure time: 1.5 hours •  16% contrast at 2.5 lp/mm

(200µm line width) •  Improvement over Ar-

Ethane mixture

8 cm

0.2

mm

0.3

mm

0.4

mm

0.5

mm

0.6

mm

Bin size: 40 x 40 µm2

20 30 40 50 60 70

0.55

0.6

0.65

0.7

0.75

0.8

0.85

0.9

0.95

Sample

Tra

nsm

issio

n

Distance from top (mm)

Remaining issues•  Data analysis: performance

of event clustering

•  Event ‘pile-up’ at rates above 100~300 kcps

•  Developing new algorithm

•  Working with software company to improve speed and ease-of-use of analysis software

TOF (ms)0 5 10 15 20 25 30 35 40

Effic

ienc

y

0

0.2

0.4

0.6

0.8

1

Neutron reconstruction efficiency

5.6 Mcps

2.5 Mcps

<0.4 Mcps

Efficiency of analysis determined by comparing numbers of raw hits and reconstructed neutron events

Other ongoing development•  New µPIC readout geometry

•  Additional strip plane at 45° to x,y strips

•  Aid in reconstruction of simultaneous events

•  Now testing at Kyoto U.

•  Reduced strip pitch

•  Manufactured using MEMS (structures down to 10µm)

•  µPIC with 280, 215µm pitches

•  Performed preliminary testing at RADEN

280 µm215 µm

y1

y2

x2 x1

u2

u1

First on-beam test of MEMS µPIC at RADEN

280µm pitch (192×192 strips)

215µm pitch (64×64 strips)

Time (ms)0 5 10 15 20 25 30 35 40

sµ

Coun

ts/p

ulse

/25

0

0.02

0.04

0.06

0.08

0.1

0.12

Neutron TOF (MEMS uPIC test)

MEMS µPIC test board

Neutron TOF spectrum measured on 215µm section

•  No signal measured on 280µm section (gain too low)

•  Signal confirmed on 215µm section

•  Further testing to study gain stability, imaging capability

µNID with Boron converter

µNID with Boron converter

•  10B-coated drift cathode (t=1µm)

•  3-axis µPIC

•  Encoder with on-board memory

•  CF4-based gas at 2 atm

•  On-beam test at RADEN early next year

~5 mm

Al drift cathode (t=1mm)

3-axis µPIC readout

Expected performance

Efficiency@25.3meV 3~5%

Time resolution 10 ns

Spatial resolution 200~400 µm

Peak count rate 20~30 Mcps

10B coating (t=1µm)

0.1

1

10

100

0.01 0.1 1 10

Co

unt r

ate

(M

cp

s)

Spatial resolution (mm)

µNID GEM

LiTA12

Current and projected performance

µNID (GbE and

optimized gas)

Boron µNID

µNID (GbE/memory

and reduced pitch)

Summary• Development of µNID detector is proceeding

•  Increased rate capacity to 8 Mcps through hardware upgrades, optimization of gas mixture

•  Need to adapt analysis algorithms to higher rate, new gas characteristics

•  Testing of ew µPIC readout boards for increased rate, higher spatial resolution has begun

•  Starting development of faster off-line data processing software

•  µNID with Boron converter •  Expect greatly improved rate (20~30 Mcps) and similar spatial

resolution thanks to smaller event size

•  Will perform on-beam test at RADEN in 2016B