実験報告書様式（一般利用課題・成果公開利用）
提出日 Date of Report

MLF Experimental Report
課題番号 Project No.

June 8, 2017
装置責任者 Name of responsible person
Dr. K. Oikawa

2016A0323

実験課題名 Title of experiment

装置名 Name of Instrument/（BL No.）

Optimization of scintillators and neutron imaging detectors using

NOBORU /(BL10)
実施日 Date of Experimentthem
実験責任者名 Name of principal investigator

May 17-18, 2016, June 14-16, 2016

Masaki Katagiri

June 23-24, 2016, Nov 14-16, 2016

所属 Affiliation

Dec 2- 3, 2016, Jan 23-24, 2017

Ibaraki University, Frontier Research Center for Applied AtomicSciences
試料、実験方法、利用の結果得られた主なデータ、考察、結論等を、記述して下さい。（適宜、図表添付のこと）
Please report your samples, experimental method and results, discussion and conclusions. Please add figures andtables for better explanation.
1. 試料 Name of sample(s) and chemical formula, or compositions including physical form.
No sample was used in the experiment. The detector performances were purely evaluated using a collimatedpulsed neutron beam only.

2. 実験方法及び結果 （実験がうまくいかなかった場合、その理由を記述してください。）
Experimental method and results. If you failed to conduct experiment as planned, please describe reasons.

Efficiency

In this allocated experimental time, optimization of an iBIX-type neutron detector and development of ahigh-resolution and high-counting-rate 2D neutron detector using a PSPMT were carried out.
(i) Optimization of an iBIX-type neutron detector
We developed new ZnS/6LiF neutron scintillators for iBIX detectors in the project of 2014B. In this project, weoptimized an iBIX-type neutron detector by combining a thin front-side scintillator with a thick rear-side
scintillator. After several combinations with a front-side and a rear-side scintillator were evaluated, we selected
an iBIX-type detector that has good detection characteristics. An absolute detection efficiency of this detector ina function of neutron wavelength was determined by a special method using a 3He proportional counter. Figure
1 shows outline of calibration experiments. Count of the 3He counter, count
1.2
of iBIX-type detector after absorption by the 3He counter and count of
1.0
iBIX-type detector after deinstallation of the counter were obtained in the0.8
experiments. By using these counts, absolute detection efficiencies of the0.6
iBIX-type detector and the 3He
0.4
counter were obtained as aCollimator
Preamplifier andEfficiency(1.4mm x 1.4mm)
discriminatorHe3 efficiency
0.2function of neutron wavelength.
Calculation
New ZnS/ LiF scintillators
0.0Neutrons
TOF data
These results are shown in Fig.2.
02468102D readoutacquisition
systemsystemWavelength of neutron,AAlso, efficiencies of the 3He
iBIX-type 2D neutron detector
Fig.2 Detection efficiencies
counter calculated by using aBL-10 instrument
He proportional counter(Installed or uninstalled)
as a function of neutron
neutron absorption cross-section
wavelength
Fig.
1
Outlineofcalibration
experimentsof 3He and an absorption length
6o3

1

2. 実験方法及び結果（つづき） Experimental method and results (continued)

Efficencyof the 3He counter are shown in same figure. It is confirmed that the0.6
measured efficiency is in agreement with the calculated efficiency. After
0.5
that, efficiency in case of both scintillators and efficiency in case of only
0.4
front-side scintillator or only rear-side scintillator were measured and0.3compared in Fig. 3. It is found out that the rear-side scintillator increases the0.2Both(New standard)
efficiency especially in short wavelength of neutrons.
Front(400/480)
0.1
Back(720/600)(ii) A 2D neutron detector using a position-sensitive PMT
002
4
6
8
10
A high-resolution and high-counting-rate 2D neutron detector using a
Wavelength of neutron,APSPMT(Position-Sensitive Photomultiplier) was developed for aFig.3
Threekindsof
refractometer and a SANS. Figure 4 shows a schematic diagram of the 2D
efficiencies as a function ofneutron detector. The largest merit in this detector is a DSP-type shaping
neutron wavelength
amplifier and high-speed ADC circuit that processes signals from a
PSPMT(Position-Sensitive Photomultiplier). This DSP has a remarkableability for high-counting signal processing with more than
New ZnS/6LiF scintillator Charge-sesitive preamplifier
100kcps. High-resolution and high-counting-rate characteristicsof the 2D neutron detector was evaluated by TOF experiments.
Hamamatsu
TOF data
The experiments were carried out by combining a collimated3" PSPMT
acquisitionR2486systembeam for position resolusion with an added beam for increase
DSP-type shaping amp. and high-speed ADC circuitof counting rate. A sample of measured 3D neutron image atFig.4
Schematic diagram of the 2D
8ms is shown in Fig. 5. Figure 6 shows a proportional relation
neutron detector
of counting rate between a collimated beam and a total
10210110010-1-310-2-1

1001010Counting rate of collimated beam, kcps

Fig.6
Proportional
relation of counting rate
between a collimatedbeam and a total beam

Fig.5
Measured3Dneutron image at 8ms

2.00.6

FWHM position resolution, mm

Proportion of only collimated beam
to that with added beam

beam(collimated beam + addedbeam). It is confirmed that a linearityof counting rate for the total beam isgood to 40kcps and becomes worse
after that because of dead time. The
effect of the added beam on counting
rate of the collimated beam is shownin Fig. 7. Proportion of counting rate
for collimated beam to that with theadded beam is almost 1 to 40kcps
and increases a little at more 52kcps.
Also, a collimated beam was only
measured under low counting rate toinquire pure position resolutions.
Figure 8 shows FWHM position
resolutions in a function of total
counting rate. The resolution of0.4mm remains unchanged to40kcps. Consequently, it is foundout that the developed 2D detector
has excellent performances to theposition resolution and the counting
rate.

Counting rate of total beam, kcps

o1.5

1.00.50.00102030

405060Counting rate of total beam, kcps

Fig.7 Effect of of added
beam on counting rate of
the collimated beam
20.50.40.3
Added beamCollimated beam only

0.2
0.1
0 -2
1010-1

1001

102

10

Counting rate of total beam, kcps

Fig.8 FWHM position
resolutions in a function oftotal counting rate