Development of a counting-type neutron imaging detector for energy- - - PowerPoint PPT Presentation

Development of a counting-type neutron imaging detector for energy- resolved imaging at J-PARC/MLF

Joe Parker CROSS-Tokai BL22 Group

1J-PARC13 October 2016

RADEN/BL22 and µNID development members

JAEA/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

Energy

meV 1 keV

Wavelength

10 10-2 Resonance absorption Bragg-edge, Magnetic imaging

Moderator Bulk shield Shutter Optical Devices Experimental Space 1st Detector position 2nd Detector position

13m 5m

Large load sample stage Optical bench Medium sample stage

0m 8m 14m 27m 31m 18m 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 RADEN

Camera 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

Count rate (Mcps) 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)

10 20 30 40 50 60

Time-above-threshold (clocks)

5 10 15 20 25 30

Energy Deposition

TOT for proton-triton track Proton Triton Neutron

Digital encoder with time-over-threshold (TOT)

Threshold

µPIC

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

Encoders DAQ PC

SiTCP

Encoders µPIC

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

4 8

Time-over-threshold (ns)

50 100 150 200 250 6 2

Template for fit

Measured TOT distribution

Proton Triton

• Strong gamma rejection

using TOT information

• Template fit for position

analysis

• Avg. time (clocks)

100 200 300 400 500

Counts/hr/3.75 clocks

1 2 3 4 5 6 7

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

DDR3 memory

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

N e u t r

• n

b e a m

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

1 2 3 4 5 500 1000 1500 2000 2500

Count rate (Mcps) 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

2 4 6 8 10 1000 2000 3000 4000

Count rate (Mcps) Slit area (mm2)

Neutron rates vs slit area

Ar-C2H6 CF4-iC4H10

50 60 70

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

0.55 0.6 0.65 0.7 0.75 0.8 0.85 0.9 0.95

Transmission Distance from top (mm)

Remaining issues

• Data analysis: performance
• f 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)

5 10 15 20 25 30 35 40

Efficiency

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 µm 215 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)

5 10 15 20 25 30 35 40

s µ Counts/pulse/25

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

Count rate (Mcps) Spatial resolution (mm) µNID GEM LiTA12

Current and projected performance

µNID

(GbE and

• ptimized 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