研究者詳細 - 瓜谷　章

論文 - 瓜谷　章

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Development of Neutron Diagnostic Systems for LHD Deuterium Experiments

T. Iguchi, A. Uritani, N. Nishio, J. Kawarabayashi, K. Watanabe, A. Yamazaki, H. Tomita, M. Sasao, A. Okamoto, S. Kitajima, K. Ishii, T. Nishitani, K. Ochiai, M. Ishikawa, K. Shinihara, J. H. Kaneko, F. Fujita, H. Harano, T. Matsumoto, E. Takada, M. Isobe, T. Tanaka, K. Nishimura, H. Yamanishi and M. Osakabe

Annual report of National Institute of Fusion Science 頁： 219 2011年11月

Study on Measurement of Total Neutron Yield during Deuterium Experiments and its Calibration

A. Uritani, N. Nishio, J. Yamazaki, K. Watanabe, H. Yamanishi and M. Isobe

Annual report of National Institute of Fusion Science 頁： 108 2011年11月

A Study on Electron Density Imaging Using the Compton Scattered X-ray CT Technique 査読有り

Ryota Masuji, Kenichi Watanabe, Atsushi Yamazaki, Akira Uritani

Nuclear Instruments and Methods in Physics Research Section A 652 巻 ( 1 ) 頁： 620-624 2011年10月

記述言語：英語掲載種別：研究論文（学術雑誌）

We propose a novel electron density imaging technique based on a Compton scattered X-ray CT (CSX-CT)
technique. We design fundamental configuration of the CSX-CT system, which consists of a fan-shaped
X-ray beam, two-dimensional sensors for scattered X-ray detection, parallel plate collimators for limitation of the direction of scattered X-rays and a line sensor for the transmission of X-ray CT
(TX-CT). An image obtained by the TX-CT can be used to correct the attenuation effect of scattered X-rays.
Through Monte Carlo simulation modeling studies of the CSX-CT system, we demonstrate that the
utilization of the information of scattered X-rays is useful to obtain the electron density image. We
additionally confirm that the medical exposure irradiated in the CSX-CT is estimated to be lower than the maximum dose recommended in the guideline of some committees.

Neutron-Gamma Discrimination Based on Pulse Shape Discrimination in a Ce:LiCaAlF₆ Scintillator 査読有り

Atsushi Yamazaki, Kenichi Watanabe, Akira Uritani, Tetsuo Iguchi, Noriaki Kawaguchi, Takayuki Yanagida, Yutaka Fujimoto, Yuui Yokota, Kei Kamada, Kentaro Fukuda, Toshihisa Suyama, Akira Yoshikawa

Nuclear Instruments and Methods in Physics Research Section A Associated Equipment 652 巻 ( 1 ) 頁： 435-438 2011年10月

記述言語：英語掲載種別：研究論文（学術雑誌）

We demonstrate neutron-gamma discrimination based on a pulse shape discrimination method in a Ce:LiCAF scintillator. We have tried neutron-gamma discrimination using a difference in the pulse shape or the decay time of the scintillation light pulse. The decay time is converted into the rise time through an integrating circuit. A 252Cf enclosed in a polyethylene container is used as the source of thermal neutrons and prompt gamma-rays. Obvious separation of neutron and gamma-ray events is achieved using the information of the rise time of the scintillation light pulse. In the separated neutron spectrum, the gamma-ray events are effectively suppressed with little loss of neutron events. The pulse shape discrimination is confirmed to be useful to detect neutrons with the Ce:LiCAF scintillator under an intense high-energy gamma-ray condition.

Development of a Gamma-Camera with a Functional Collimator 査読有り

Kenichi Watanabe, Junichi Sugiyama, Atsushi Yamazaki, Akira Uritani

Nuclear Instruments and Methods in Physics Research Section AAssociated Equipment 652 巻 ( 1 ) 頁： 582-586 2011年10月

Development of a Compact Flat Response Neutron Detector 査読有り

H. Harano, T. Matsumoto, J. Nishiyama, A. Masuda, A. Uritani, K. Kudo

58 巻 ( 5 ) 頁： 2421-2425 2011年10月

記述言語：英語掲載種別：研究論文（学術雑誌）

Long counters are widely used as neutron fluence monitors for their flat response. However, a bulky neutron moderator is required to achieve the flat response, which can be a disadvantage for portability and an undesirable source of scattered neutrons. Reducing the size of the moderator degrades the flat response, especially for high-energy neutrons. We propose a new method to reduce the size of the moderator while keeping a flat response, and we develop a compact flat-response neutron detector. The detector consists of two small spherical $^{3}$ He proportional counters embedded at appropriate positions in a compact cylindrical polyethylene moderator. The sensitivity ratio between the two counters was adjusted to provide a flat response in the total outputs from the two counters. We demonstrated by MCNPX calculations and response measurements for Cf and Am-Be neutrons and monoenergetic neutrons that the present detector had a sensitivity comparable to long counters with a good flat response in a wide energy range up to 20 MeV while being only one-fifth of the weight of long counters. The positions of the effective center were determined as a function of neutron energy. We also proposed a method to evaluate the neutron energy using the detector, which will allow various new applications taking advantage of the ability to measure neutron fluence and energy at the same time.

DOI： 10.1109/TNS.2011.2163191

Flat-response Neutron Detector Using Spatial Distribution of Thermal Neutrons in a Moderator 査読有り

Kenichi Watanabe, Junpei Otsuka, Musashi Shigeyama, Yousuke Suzuki, Atsushi Yamazaki, Akira Uritani

Nuclear Instruments and Methods in Physics Research Section A 652 巻 ( 1 ) 頁： 392-396 2011年10月

記述言語：英語掲載種別：研究論文（学術雑誌）

We propose a novel neutron detector that realized flat-response using information of a spatial
distribution of thermal neutrons in a moderator. The proposed detector consists of a 3He position sensitive proportional counter(PSPC) and a cylindrical moderator surrounding the 3He PSPC. The
cylindrical detector is irradiated by neutrons along the cylinder axis. The spatial response of the 3He
PSPC is used to correct the detector response in to flat-response. We adopt a weighting method to
achieve flat-response, in which detected neutrons weighted depending on their detected positions are
accumulated as the detector response. Through Monte Carlo simulation studies, we confirm that the
flat-response neutron detector can be realized by correcting the response of the proposed detector
using the weights determined by a multiple least squar emethod (MLSM). Additionally, fundamental
property of the 3He PSPC is experimentally investigated to check applicability to the proposed flat-response neutron detector. We conclude that we should take account of the end effect when
determining the weights and correcting the detector response.

Europium and Sodium Codoped LiCaAlF₆ Scintillator for Neutron Detection 査読有り

Takayuki Yanagida, Akihiro Yamaji, Noriaki Kawaguchi, Yutaka Fujimoto, Kentaro Fukuda, Shunsuke Kurosawa, Atsushi Yamazaki, Kenichi Watanabe, Yoshisuke Futami, Yuui Yokota, Akira Uritani, Tetsuo Iguchi, Akira Yoshikawa, and Martin Nikl

Applied Physics Express 4 (2011) 126402 4 巻頁： 106401-106403 2011年9月

Study on the Calibration of LHD Neutron Monitoring System 査読有り

Naoto Nishio, Atsushi Yamazaki, Kenichi Watanabe, Akira Uritani, Mitsutaka Isobe and Hirokuni Yamanishi

Plasma and Fusion Research 6 巻頁： 2405115-1 - 2405115-4 2011年8月

記述言語：英語掲載種別：研究論文（学術雑誌）

Neutron monitoring is quite important because neutron yield generated by fusion reactions corresponds to
the fusion output. In design of the neutron monitor, Monte Carlo simulations play an important role to make
corrections on various parameters, such as neutron energy spectrum and spatial distribution when determining the calibration constant. We consider the calibration procedures using a Cf point source toroidally rotating in the vacuum vessel, and evaluate uncertainties of the calibration constant for the neutron detector placed on the center
axis.

Basic Study of Europium Doped LiCaAlF₆ Scintillator and its Capability for Thermal Neutron Imaging Application 査読有り

Takayuki Yanagida, Noriaki Kawaguchi, Yutaka Fujimoto, Kentaro Fukuda, Yuui Yokota, Atsushi Yamazaki, Kenichi Watanabe, Jan Pejchal, Akira Uritani, Tetsuo Iguchi and Akira Yoshikawa

33 巻 ( 8 ) 頁： 1243-1247 2011年6月

New Idea of a Small-Sized Neutron Detector with a Plastic Fibre 査読有り

Tetsuro Matsumoto, Hideki Harano, Akihiko Masuda, Jun Nishiyama, Yoshinori Sakurai and Akira Uritani

Radiation Protection Dosimetry 146 巻 ( 1-3 ) 頁： 92-95 2011年4月

Absolute Measurement of Activity of ¹⁹⁸Au Foils Using the 4πβ–γ Coincidence Counting Method and Corrections by the Monte Carlo Simulation 査読有り

Jun Nishiyama, Hideki Harano, Tetsuro Matsumoto, Yasushi Sato, Akira Uritani and Katsuhisa Kudo

Radiation Protection Dosimetry 頁： 1-5 2011年3月

Recent Activities on Neutron Standardization in Japan

Hideki HARANO, Tetsuro MATSUMOTO, Jun NISHIYAMA, Akihiko MASUDA, Akira URITANI, Katsuhisa KUDO

Progress in NUCLEAR SCIENCE and TECHNOLOGY 1 巻頁： 138-141 2011年

Thermal Neutron Calibration Method Using an Intense Neutron Beam from JRR-3M 査読有り

T. Matsumoto, H. Harano, J. Nishiyama, H. Matsue, A. Masuda, A. Uritani and K. Kudo

Radiation Measurements 45 巻 ( 10 ) 頁： 1124-1126 2010年12月

記述言語：英語掲載種別：研究論文（学術雑誌）

We have developed a thermal neutron calibration method using a reactor produced neutron beam in JRR-3M of the Japan Atomic Energy Agency. Neutron-induced prompt gamma ray analysis has usually been performed in this beam line. Neutron energy distributions with negligible contributions from epithermal neutrons were measured by a time-of-flight method with a chopper made of 6LiF powder. The thermal neutron flux was determined by a gold foil activation method. We found that the thermal neutron beam in JRR-3M was well suited for calibration, neutron detector development or neutron dosimetry.

A Study on the Neutron Monitoring System of LHD Based on Monte Carlo Simulations 査読有り

N. Nishio, S. Yamamoto, K. Watanabe, A. Uritani, M. Isobe, and H. Yamanishi

Review of Scientific Instruments 81 巻頁： 10D-306-1-10D-306-3 2010年10月

記述言語：英語掲載種別：研究論文（学術雑誌）

Neutron monitoring is quite important because fusion neutrons are a direct evidence of fusion reactions. In calibration experiments of a neutron monitoring system, Monte Carlo calculations play an important role to correct various effects. To perform Monte Carlo calculations for a helical type fusion device, we make a program that can automatically generate an input file of a helical coil geometry for the MCNP code. The neutron spatial distributions and spectra for the helical devices are calculated in the geometries automatically generated by this program. We also discuss in calibration experiments.

Fusion Product Diagnostics Planned for Large Helical DeviceDeuterium Experiment 査読有り

M. Isobe, H. Yamanishi, M. Osakabe, H. Miyake, H. Tomita, K. Watanabe, H. Iwai, Y. Nomura, N. Nishio, K. Ishii, J. H. Kaneko, J. Kawarabayashi, E. Takada, A. Uritani, M. Sasao, T. Iguchi, Y. Takeiri and H. Yamada

Review of Scientific Instruments 81 巻頁： 10D-310-1-10D-310-5 2010年10月

記述言語：英語掲載種別：研究論文（学術雑誌）

Deuterium experiment on the Large Helical Device LHD is now being planned at the National Institute for Fusion Science. The fusion product diagnostics systems currently considered for installation on LHD are described in this paper. The systems will include a time-resolved neutron yield monitor based on neutron gas counters, a time-integrated neutron yield monitor based on activation techniques, a multicollimator scintillation detector array for diagnosing spatial distribution of neutron emission rate, 2.5 MeV neutron spectrometer, 14 MeV neutron counter, and prompt -ray diagnostics.

中性子測定器の校正技術招待有り

松本哲郎、原野英樹、工藤勝久、瓜谷章

放射線 34 巻 ( 2 ) 頁： 101-109 2008年4月

中性子標準のトレーサビリティーと国際相互比較招待有り

原野英樹、松本哲郎、工藤勝久、瓜谷章

放射線 34 巻 ( 2 ) 頁： 111-115 2008年4月

Development of the Fast Neutron Standard Using a Be(α,n) Reaction at the National Metrology Institute of Japan 査読有り

T. Shimoyama, H. Harano, T. Matsumoto, K. Moriyama, T. Hata, K. Kudo, T. Koyamada, and A. Uritani

Radiation Protection and Dosimetry 126 巻頁： 130-133 2007年8月

Characterization of Kilo Electron Volt Neutron Fluence Standard with the ⁴⁵Sc(p,n)⁴⁵Ti Reaction at NMIJ 査読有り

T. Matsumoto, H. Harano, T. Shimoyama, K. Kudo, and A. Uritani

Radiation Protection and Dosimetry 126 巻頁： 155-158 2007年8月

記述言語：英語掲載種別：研究論文（学術雑誌）

We are developing a national standard of a monoenergetic kilo electron volt neutron field with the 45Sc(p,n)45Ti resonance reaction. A wide resonance yields 27.4 keV neutrons at 0° with respect to the proton beam. The proton energy was precisely determined in the measurement of the relative neutron yield as a function of the proton energy from the threshold energy to 2.942 MeV. Absolute measurement of the monoenergetic neutron fluence was performed using a 3He proportional counter. Relative measurement was also carried out using a Bonner sphere calibrated at our 144 keV standard neutron field. Calibration factors were obtained between the count of a neutron monitor and the neutron fluence. A silicon-surface barrier detector with a 6LiF foil converter was also being developed for the neutron fluence measurement. Successful results were obtained in the tests in the 144 keV standard neutron field.

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