Faculty Profiles - URITANI Akira

Papers - URITANI Akira

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Development of One-Dimensional Position-Sensitive Neutron Detector Using TRUST Eu:LiCAF Scintillator Reviewed

Hiroaki SHIMIZU, Koichi KINO, Setsuo SATO, Kenichi WATANABE, Akira URITANI, Sachiko YOSHIHASHI and Atsushi YAMAZAKI

JPS Conf. Proc. Vol. 22 page： 011020-1 - 011002-8 2018.11

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)

We developed a one-dimensional position-sensitive neutron detector using Transparent RUbber SheeT type Eu:LiCaAlF6 (TRUST Eu:LiCAF) scintillators and a newly proposed wavelength-shifting fiber (WLSF) readout. The proposed position-sensitive WLSF readout consists of a number of WLSFs optically divided to distinguish the scintillation position. We experimentally compared the position sensitivities of the optically divided WLSF type detector and a conventional one using light attenuation in the WLSFs. We concluded that the proposed detector had higher spatial resolution than that of the conventional one. Additionally, we fabricated a prototype version of the optically divided WLSF type detector. We determined the prototype detector had a relative spatial resolution of approximately 20 %.

DOI： 10.7566/JPSCP.22.011020

Neutron Diagnostics in the Large Helical Device Reviewed

Mitsutaka Isobe, Kunihiro Ogawa, Takeo Nishitani, Hitoshi Miyake, Takashi Kobuchi, Neng Pu, Hoiroki Kawase, Eiji Takada, Tomoyo Tanaka, Siyuan Li, Sachiko Yoshihashi, Akira Uritani, Jungmin Jo, Sadayoshi Murakami, Masaki Osakabe

IEEE Transactions on Plasma Science Vol. 46 ( 6 ) page： 2050 - 2058 2018.6

Language：English Publishing type：Research paper (scientific journal)

The deuterium operation of the large helical device (LHD) began in March 7, 2017, after long-term preparation and commissioning of apparatuses necessary for execution of the deuterium experiment. A comprehensive set of neutron diagnostics was developed and installed onto LHD through numerous efforts in preparation. Neutron diagnostics play an essential role in both neutron yield management for the radiation safety and extension of energetic-particle physics study in LHD. Neutron flux monitor (NFM) characterized by fast-response and wide dynamic range capabilities is successfully working. Total neutron emission rate reached 3.3×10¹⁵(n/s) in the first deuterium campaign of LHD. The highest neutron emission rate was recorded in inward shifted configuration. Neutron yield evaluated by neutron activation system agrees with neutron yield measured with NFM. Performance of vertical neutron camera was demonstrated. Neutron emission profile was inwardly shifted in the inwardly shifted configuration, whereas it was outwardly shifted in the outwardly configuration. Secondary deuterium-tritium neutrons produced by triton burnup in LHD deuterium plasmas were detected for the first time in stellarator/heliotron devices in the world. Similar to total neutron emission rate, the inward shifted configuration provided highest triton burnup ratio.

DOI： 10.1109/TPS.2018.2836987

Web of Science

二種類の光刺激蛍光体と光ファイバーを用いたハイブリッド小型線量計による炭素線照射時に発生する消光現象の補正法の検討

平田悠歩、山﨑淳、渡辺賢一、吉橋幸子、瓜谷章、古場裕介、松藤成弘、柳田健之、福田健太郎

放射線 Vol. 43 ( 4 ) page： 139-142 2018.1

In situ calibration of neutron activation system on the large helical device Reviewed

N. Pu, T. Nishitani, M. Isobe, K. Ogawa, H. Kawase, T. Tanaka, S. Y. Li, S. Yoshihashi and A. Uritani

Review of Scientific Instruments Vol. 88 ( 11 ) page： 113302 2017.11

Language：English Publishing type：Research paper (scientific journal)

In situ calibration of the neutron activation system on the Large Helical Device (LHD) was performed by using an intense ²⁵²Cf neutron source. To simulate a ring-shaped neutron source, we installed a railway inside the LHD vacuum vessel and made a train loaded with the ²⁵²Cf source run along a typical magnetic axis position. Three activation capsules loaded with thirty pieces of indium foil-stacked with total mass of approximately 18 g were prepared. Each capsule was irradiated over 15 hours while the train was circulating. The activation response coefficient (9.4 ± 1.2)×10^-8 of ¹¹⁵In(n, n')^115mIn reaction obtained from the experiment is in good agreement with results by three-dimensional neutron transport calculations using the MCNP 6 code. The activation response coefficients for 2.45 MeV birth neutron and secondary 14.1 MeV neutron from deuterium plasma were evaluated from the activation response coefficient obtained in this calibration experiment.

Correction of quenching effect of a small size OSL dosimeter using Eu:BaFBr and Ce:CaF₂

Hirata Yuho, Watanabe Kenichi, Uritani Akira, Yamazaki Atsushi, Koba Yusuke, Matsufuji Naruhiro, Yanagida Takayuki, Fukuda Kentaro

RADIATION MEASUREMENTS Vol. 106 page： 246 - 251 2017.11

<i>In situ</i> calibration of neutron activation system on the large helical device

Pu, N; Nishitani, T; Isobe, M; Ogawa, K; Kawase, H; Tanaka, T; Li, SY; Yoshihashi, S; Uritani, A

REVIEW OF SCIENTIFIC INSTRUMENTS Vol. 88 ( 11 ) 2017.11

名古屋大学における加速器BNCT用システムの開発― Li封入型ターゲットの除熱方法の検討― Invited

古澤大貴、瓜谷章、渡辺賢一、吉橋幸子、山崎淳、鬼柳善明、土田一輝、辻義之、恒吉達矢、浜地志憲、時谷政行、田村仁、相良明男

Vol. 4 page： 22-23 2017.9

Correction of quenching effect of a small size OSL dosimeter using Eu:BaFBr and Ce:CaF₂ Reviewed

Yuho Hirata, KenichiWatanabe, AkiraUritani, AtsushiYamazaki, Yusuke Koba, Naruhiro Matsufuji, TakayukiYanagida, Kentaro Fukuda

Radiation Measurements Vol. 106 page： 246-251 2017.4

Language：English Publishing type：Research paper (scientific journal)

To accurately estimate an actual dose during radiotherapy treatment, dosimeters are required to be inserted into the affected region in a patient's body. Therefore, we are developing a small size dosimeter consisting of optical fibers and optically stimulated luminescence (OSL) elements. We fabricated two types of small size dosimeters using Eu:BaFBr and Ce:CaF₂. We measured the Bragg peak of high energy carbon ions in a water equivalent material. OSL materials showed the quenching effect when irradiated by high linear energy transfer (LET) particles. The sensitivity of Eu:BaFBr and Ce:CaF₂ monotonically decreased with different coefficients. The ratio of the signal intensity of these two OSL materials can uniquely determine the sensitivity of each OSL material. We corrected the quenching effect of the OSL dosimeters in the spread out Bragg peak with this relationship.

Particle Dependence of Quenching Effect in an Optical-Fiber-Type Optically Stimulated Luminescence Dosimeter

Hirata Yuho, Watanabe Kenichi, Yoshihashi Sachiko, Uritani Akira, Koba Yusuke, Naruhiro Matsufuj I, Yanagida Takayuki, Toshito Toshiyuki, Fukuda Kentaro

SENSORS AND MATERIALS Vol. 29 ( 10 ) page： 1455 - 1464 2017

Upgrade of neutron energy spectrometer with single multilayer Bonner sphere using onion-like structure Reviewed

T. Mizukoshi, K. Watanabe, A. Yamazaki, A. Uritani, T. Iguchi, T. Ogata and T. Muramatsu

Journal of Radiation Protection and Research Vol. 41 ( 3 ) page： 185-190 2016.9

Quenching Effect in an Optical Fiber Type Small Size Dosimeter Irradiated with 290 MeV·u^-1 Carbon Ions Reviewed

Vol. 41 ( 3 ) page： 222-228 2016.9

Recent Progress in the Fusion Neutronics 7. Status of the Fusion Neutronics in the Domestic Fusion Facilities

SUKEGAWA Atsuhiko, URITANI Akira, NISHIMURA Kiyohiko and NISHITANI Takeo

JOURNAL OF PLASMA AND FUSION RESEARCH Vol. 92 ( 4 ) page： 282-285 2016.4

Basic study on response of a small size dosimeter using optical fiber and Ce:CaF₂ OSL element

Hirata, Y.; Watanabe, K.; Yamazaki, A.; Uritani, A.; Koba, Y.; Matsufuji, N.; Yanagida, T.; Fukuda, K.

Vol. 41 ( 3 ) page： 157-161 2016

Language：Japanese Publishing type：Research paper (scientific journal)

We fabricated a small size optical fiber type dosimeter system using Ce:CaF₂ OSL element. We evaluated basic response of fabricated dosimeter to radiations of X-ray and high-energy carbon ions. When irradiating X-ray, good linearity can be confirmed. With increasing linear energy transfer (LET) of carbon ions, luminescence efficiency of Ce:CaF₂ decreases. Compared with the conventional small dosimeter using Eu:BaFBr OSL element, Ce:CaF₂ shows a small deterioration in the luminescence efficiency.

Study on neutron energy spectrometer with onion-like single bonner sphere using TRUST Eu:LiCAF scintillator

Mizukoshi, T.; Watanabe, K.; Yamazaki, A.; Uritani, A.; Iguchi, T.; Ogata, T.; Muramatsu, T.

Vol. 41 ( 3 ) page： 151-155 2016

Language：Japanese Publishing type：Research paper (scientific journal)

We fabricated the prototype of a single sphere neutron spectrometer with five sensitive layers using the Transparent FUbber SheeT Eu:LiCaAlF₆ (TRUST Eu:LiCAF) scintillator and the wavelength-shifting fibers (WLSFs). We confirmed that the fabricated detector shows a clear neutron peak and can discriminate neutron and gamma-ray events in signal pulse height spectra. We additionally compared the neutron sensitivity between the new TRUST Eu:LiCAF type and the previous LiF-ZnS mixed powder type. The sensitivity of the new one is 40 times higher than that of the previous one.

Study on Effects of Gamma-Ray Irradiation on TlBr Semiconductor Detectors Reviewed

Motohiro Matsumura, Kenichi Watanabe, Atsushi Yamazaki, Akira Uritani, Norihisa Kimura, Nobumichi Nagano, and Keitaro Hitomi

JPS Conf. Proc. Vol. 11 page： 030005-1 - 030005-5 2016

Wavelength-shifting fiber signal readout from Transparent RUbber SheeT (TRUST) type LiCaAlF₆ neutron scintillator Reviewed

Kenichi Watanabe, Takuya Yamazaki, Dai Sugimoto, Atsushi Yamazaki, Akira Uritani, Tetsuo Iguchi, Kentaro Fukuda, Sumito Ishidu, Takayuki Yanagida, Yutaka Fujimoto

Nuclear Instruments and Methods A Vol. 784 page： 260-263 2015.6

Language：English Publishing type：Research paper (scientific journal)

As an alternative to the standard 3He neutron detector, we are developing the Transparent RUbber SheeT type (TRUST)Eu doped LiCaAlF6 (Eu:LiCAF)scintillator. This type of neutron scintillator can easily be fabricated as a large area sheet. In order to take advantage of a large area detector, we try to read out scintillation photons using a wavelength-shifting fiber (WLSF) from a TRUSTEu:LiCAF scintillator. The TRUST Eu:LiCAF scintillator with the size of 50x50x5 mm3 was mounted on the WLSF plate and the end of the WLSFs was connected with a PMT. In order to reject high pulse height events induced in the WLSFs, we applied the pulse shape discrimination technique. The gamma-ray intrinsic and neutron
absolute detection efficiency is evaluated to be 8.8x10^7 and 9x103 cps/ng Cf(2m) for the TRUSTEu:
LiCAF scintillator with the size of 50x50x5 mm^3.

Development of X-ray backscatter system to inspect the inner structure of concrete Invited

Hiroyuki Toyokawa, Shinichi Mandai, Akira Uritani, Kenichi Watanabe

page： 0 2015.5

Language：Japanese

There are more than 700 thousand road bridges, whose lengths are longer than 2 m. Sixteen percent of them were built more than 50 years ago, and their fraction will increase to 40% and 65%, in next 10 years and 20 years, respectively. The maintenance, inspection and repair of them are managed mainly by a local government, which the infrastructures are located. However, the management of the infrastructure is becoming more difficult for the local governments, because of the lack of a financial resource, human resource, and technical knowledge. In Japan, the deterioration of the infrastructures by the sea wind and the salt is serious especially for the roadbed and the reinforced concrete due to the corrosion. Nondestructive inspection methods, which are currently being applied on-site are not enough to measure the degree of damage of concretes, quantitatively. So, a novel method for nondestructive inspection of inner structure of concrete with radiation instrumentation and electron accelerator, which uses X-ray backscatter is being developed. The X-ray backscatter system, which has advantages in highly precise image and one-sided accessibility in inspection, is developed for use in inspecting roadbed and bridge, as a compact and light-weight system. Nondestructive inspection by visualization, using a high resolution X-ray backscatter image for reinforcement bar and a pot-hole inside concrete structure will be possible.

Development of an optical fiber type detector using a Eu:LiCaAlF₆ scintillator for neutron monitoring in boron neutron capture therapy Reviewed

Kenichi Watanabe, Yuya Kawabata, Atsushi Yamazaki, Akira Uritani, Tetsuo Iguchi, Kentaro Fukuda, Takayuki Yanagida

Nuclear Instruments and Methods in Physics Research A Vol. A802 page： 1-4 2015

Portable Neutron Detector Using Ce:LiCaAlF₆ Scintillator Reviewed

Kenichi Watanabe, Takayuki Yanagida, Kentaro Fukuda, Akifumi Koike, Toru Aoki and Akira Uritani

SENSORS AND MATERIALS Vol. 27 ( 3 ) page： 269-275 2015

Language：English Publishing type：Research paper (scientific journal)

We fabricated a prototype portable neutron detector using a Ce:LiCaAlF₆ (Ce:LiCAF) scintillator and evaluated its basic performance. The weight of the fabricated detector including the battery is 800 g, significantly less than that of the conventional portable neutron detector, which weighs more than 5 kg. The neutron sensitivity of the fabricated detector is evaluated to be 2.3 cps/(mu Sv/h), comparable to that of the conventional detector. The gamma-ray intrinsic detection efficiency is evaluated to be less than 10(-6). The gamma-ray sensitivity is sufficiently low under ordinary circumstances. The expected count rate of the error counting due to the pile-up effect of gamma-ray-induced events is confirmed to be less than the background count rate for an incident gamma-ray rate of less than 10(4) gammas/s.

Study on fast luminescence component induced by gamma-rays in Ce doped LiCaAlF₆ scintillators Reviewed

Kenichi Watanabe, Yoshiyuki Kondo, Atsushi Yamazaki, Akira Uritani, Tetsuo Iguchi, Noriaki Kawaguchi, Kentaro Fukuda, Sumito Ishizu, Takayuki Yanagida, Yutaka Fujimoto, Akira Yoshikawa

Radiation Measurements Vol. 71 page： 158-161 2014.12

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Papers - URITANI Akira