Faculty Profiles - YOSHIHASHI Sachiko

Development of thermal neutron moderator for testing boron agents for Boron Neutron Capture Therapy (BNCT)

Ichikawa G, Tsuchida K, Kiyanagi Y, Ishikawa A, Hirata Y, Yoshihashi S, Watanabe K, Uritani A, Hamano T, Ogawara R, Suda M, Igawa K

JOURNAL OF INSTRUMENTATION Vol. 14 ( 06 ) page： T06010 - T06010 2019.6

Improvement of the single edge fitting mode in the Bragg edge analysis code RITS

Ohmae Kazuma, Watanabe Kenichi, Uritani Akira, Yamazaki Atsushi, Yoshihashi Sachiko, Kiyanagi Yoshiaki, Sato Hirotaka

JSAP Annual Meetings Extended Abstracts Vol. 2019.1 ( 0 ) page： 561 - 561 2019.2

Measurement of BNCT Neutron Field Using Optical Fiber-Based Neutron Detector

Ishikawa Akihisa, Yamazaki Atsushi, Watanabe Kenichi, Yoshihashi Sachiko, Uritani Akira, Tsurita Yukio, Tsuchida Kazuki, Kiyanagi Yoshiaki

JSAP Annual Meetings Extended Abstracts Vol. 2019.1 ( 0 ) page： 526 - 526 2019.2

Response evaluation of Onion-like single Bonner sphere neutron spectrometer using TRUST Eu:LiCAF scintillator

Watanabe Kenichi, Mizukoshi Tomoaki, Yamazaki Atsushi, Yoshihashi Sachiko, Uritani Akira, Iguchi Tetsuo, Ogata Tomohiro, Muramatsu Takashi, Matsumoto Tetsuro, Masuda Akihiko

Progress in Nuclear Science and Technology Vol. 6 ( 0 ) page： 122 - 125 2019.1

Language：English Publishing type：Research paper (scientific journal) Publisher：Atomic Energy Society of Japan

We have developed the single sphere neutron spectrometer with five sensitive layers using the TRUST Eu:LiCAF scintillator and the WLSF readout. We evaluated the energy dependence of the detector response at thermal neutron and 24 keV, 144 keV, 565 keV, 5MeV and 14.8 MeV mono-energetic neutron irradiation fields. The experimentally determined neutron sensitivities are consistent with the Monte Carlo calculations. The detector responses for a bare and a heavy-water moderated 252Cf sources also show good agreement with the expected ones using the Monte Carlo calculations.

DOI： 10.15669/pnst.6.122

Basic evaluation of the Eu:BaFBr and Ce:CaF2 hybrid type optical fiber based dosimeter system for correction of quenching effect under carbon ion irradiation

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

Progress in Nuclear Science and Technology Vol. 6 ( 0 ) page： 238 - 242 2019.1

Language：English Publishing type：Research paper (scientific journal) Publisher：Atomic Energy Society of Japan

We fabricated the hybrid type optical fiber based dosimeter system using Eu:BaFBr and Ce:CaF2 optically stimulated luminescence (OSL) materials in order to correct the quenching effect under high LET particle irradiation. The fabricated dosimeter probe can obtain signals from both OSL materials through one optical fiber. We investigated the probe response by irradiating it with mono-energetic carbon ions and broad-spectrum ones making the spread-out Bragg peak (SOBP). We demonstrated that the SOBP shape can be improved by correction of the quenching effect using the relationship between the luminescence efficiency and the signal intensity ratio of both OSL materials.

DOI： 10.15669/pnst.6.238

Evaluation of imaging plate measurement for activated indium as fast-neutron detector in large radiation field

Kobayashi Makoto, Nishitani Takeo, Kato Akemi, Saze Takuya, Tanaka Tomoyo, Yoshihashi Sachiko, Ogawa Kunihiro, Isobe Mitsutaka

Progress in Nuclear Science and Technology Vol. 6 ( 0 ) page： 58 - 62 2019.1

Language：English Publishing type：Research paper (scientific journal) Publisher：Atomic Energy Society of Japan

The application of imaging plate (IP) method using indium foils to measure the distribution of fast neutron in large area was evaluated in this work. The radioactive nuclides of indium were individually quantified by high-purity germanium detector (HPGe) and chronological IP measurements. The detection efficiencies of each radioactive nuclide for various thicknesses of foil mylar polyester film were summarized. The scope of application for proposed method were clearly dependent on the flux ratio of fast and thermal neutron, limiting the applicable region only being close to the neutron source.

DOI： 10.15669/pnst.6.58

Measurement of Thermal and Epithermal Neutron Flux Distribution in the Torus Hall of LHD using Activation Method in the First Deuterium Experiment Campaign

TANAKA Tomoyo, KOBAYASHI Makoto, YOSHIHASHI Sachiko, URITANI Akira, WATANABE Kenichi, YAMAZAKI Atsushi, NISHITANI Takeo, OGAWA Kunihiro, ISOBE Mitsutaka

Plasma and Fusion Research Vol. 14 ( 0 ) page： 3405162 - 3405162 2019

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Japan Society of Plasma Science and Nuclear Fusion Research

In the Large Helical Device (LHD) of the National Institute for Fusion Science, a deuterium plasma experiment was performed in March 2017. Neutrons with an energy of 2.45 MeV are generated by d (d, n) 3He reactions. The evaluation of this neutron flux in the torus hall, as well as within the LHD vessel, is very important for the decommissioning of the LHD in the future and the radiation shielding for workers and components around the LHD. In this study, we evaluate the spatial distribution of thermal and epithermal neutron flux on the floor level of the LHD torus hall by measuring the neutron activation of gold foils. The flux information obtained in the experiment can be used for the evaluation of radio-activation and the shielding design.

DOI： 10.1585/pfr.14.3405162

Numerical heat transfer study of turbulent square-duct flow through inline V-shaped discrete ribs

Yu Stu. Shichao, Tsuneyoshi Tatsuya, Yoshihashi Sachiko, Hamaji Yukinori, Ito Takahiro, Tsuji Yoshiyuki

The Proceedings of the Fluids engineering conference Vol. 2019 ( 0 ) page： OS8-07 - 7 2019

Language：English Publishing type：Research paper (scientific journal) Publisher：The Japan Society of Mechanical Engineers

A numerical study has been conducted to examine turbulent flow and heat transfer characteristics in a three-dimensional square-duct with V-shaped ribs. The computations are based on RANS and LES models. Water is the working fluid with the flow rate of which Reynolds numbers equals to 18500. The computation reveals that two symmetrical fully developed helical flow and developed heat transfer profile are generated. Effects of different rib shape on thermal characteristics for a ribbed duct flow are investigated. The change of the shape leads to increase in heat transfer and pressure loss. The velocity profile in the vicinity of ribs and streamline has been investigated, indicates that the different flow structures generated by the rib shape leads to superior heat transfer performance. Vortices are visualized, which indicates the connection between the heat transfer and flow structure

DOI： 10.1299/jsmefed.2019.os8-07

First measurements of thermal neutron distribution in the LHD torus hall generated by deuterium experiments Open Access

Kobayashi Makoto, Tanaka Tomoyo, Nishitani Takeo, Ogawa Kunihiro, Isobe Mitsutaka, Kato Akemi, Saze Takuya, Yoshihashi Sachiko, Osakabe Masaki

FUSION ENGINEERING AND DESIGN Vol. 137 page： 191 - 195 2018.12

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

For the estimation of the neutron field generated by deuterium plasma operation in the Large Helical Device (LHD), the first measurement of the thermal neutron distribution on the floor level of the LHD torus hall was carried out. For the thermal neutron detection, indium was used as activation foils. The radioactivity of these foils were evaluated by a high-purity germanium detector (HPGe) and an imaging plate (IP). The major components of radioactive isotope of indium was 116mIn. The mapping of thermal neutron distribution in the torus hall was performed. The interactions between neutron and components around LHD were observed in the thermal neutron distribution. Also, the borated polyethylene blocks effectively absorbed the thermal neutron. The thermal neutron distribution evaluated in this work can be helpful to predict the amount of radioactive waste in the torus hall proceeding with deuterium experiment in LHD.

DOI： 10.1016/j.fusengdes.2018.09.013

Improved Design of the Exit of a Beam Shaping Assembly for an Accelerator-driven BNCT System in Nagoya University

Kazuya Sato, Akira Uritani, Kenichi Watanabe, Sachiko Yoshihashi, Atsushi Yamazaki, Yoshiaki Kiyanagi, Kazuki Tsuchida

Proceedings of the International Conference on Neutron Optics (NOP2017) 2018.11

Calibration experiment and the neutronics analyses on the LHD neutron flux monitors for the deuterium plasma experiment

Nishitani Takeo, Ogawa Kunihiro, Isobe Mitsutaka, Kawase Hiroki, Pu Neng, Kashchuk Yuri, Krasilnikov Vitaly, Jo Jungmin, Cheon Munseong, Tanaka Tomoyo, Yoshihashi Sachiko, Li Siyuan, Osakabe Masaki

FUSION ENGINEERING AND DESIGN Vol. 136 page： 210 - 214 2018.11

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

Prior to the deuterium experiments of the Large Helical Device (LHD), an in situ neutron calibration experiment was carried out by using an 800 MBq 252Cf neutron source in November 2016, where a neutron flux monitor, a neutron activation system and a vertical neutron camera are calibrated. This paper concentrates on the in situ calibration for the neutron flux monitor. The neutron flux monitor based on 235U fission chambers and 10B and 3He proportional counters are positioned at three locations outside the LHD cryostat. The counts are measured during continuous rotation of the 252Cf neutron source on the typical magnetic axis of the plasma by a toy train, where the neutron source can be regarded as a ring neutron source. Detection efficiencies for the 252Cf ring source are derived by (total counts)/(total emitted neutron number) in the continuous rotation of the neutron source. Detection efficiencies for the real plasma neutron source are obtained from the measured detection efficiencies with the correction factor taking account of the deference between the 252Cf ring source and the real plasma neutron source evaluated by MCNP calculations with the three-dimensional model of the LHD. Finally, the uncertainty of the total neutron emission rate measurement is discussed.

DOI： 10.1016/j.fusengdes.2018.01.053

Neutron Diagnostics in the Large Helical Device Open Access

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

IEEE TRANSACTIONS ON PLASMA SCIENCE Vol. 46 ( 6 ) page： 2050 - 2058 2018.6

Language：Japanese 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 $3.3 \times 10^{15}$ (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

Measurement of transient flow characteristics of target flow in water experiment for IFMIF

What’s diversity for?

Yoshida Hiroko, Yoshihashi Sachiko

Journal of the Atomic Energy Society of Japan Vol. 60 ( 5 ) page： 303 - 306 2018

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

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

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 foils stacked with total mass of approximately 18 g were prepared. Each capsule was irradiated over 15 h 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 from three-dimensional neutron transport calculations using the Monte Carlo neutron transport simulation code 6. The activation response coefficients of 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 with results from three-dimensional neutron calculations using the Monte Carlo neutron transport simulation code 6.

DOI： 10.1063/1.5009475

Matsuda Shotaro, Kanemura Takuji, Kondo Hiroo, Kaji Sayaka, Okita Takafumi, Yoshihashi Sachiko, Hoashi Eiji, Horiike Hiroshi

FUSION ENGINEERING AND DESIGN Vol. 124 page： 1096 - 1100 2017.11

Study of the correction method for quenching effects of a small size dosimeter using an optical fiber and optically stimulated luminescence

Hirata Yuho, Yamazaki Atsushi, Watanabe Kenichi, Yoshihashi Sachiko, Uritani Akira, Koba Yusuke, Matsufuji Naruhiro, Toshito Toshiyuki, Yanagida Takayuki

JSAP Annual Meetings Extended Abstracts Vol. 2017.2 ( 0 ) page： 453 - 453 2017.8

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

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

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：MYU, SCIENTIFIC PUBLISHING DIVISION

To monitor an actual dose in a patient's body during radiotherapy treatment, we have developed a small-size dosimeter of an optical fiber probe mounting optically stimulated luminescence (OSL) materials at the tip. The OSL materials show a quenching effect when they are irradiated by charged particles with high linear energy transfer (LET). We evaluate the particle dependence on the quenching effect in the small-size OSL dosimeter probe. Eu:BaFBr and Ce:CaF2 were adopted as OSL materials, and two types of small-size dosimeter were fabricated. We irradiated 290 MeV/u carbon ions, 150 MeV/u helium ions, and 225 MeV protons and measured the Bragg peak. The Eu:BaFBr small-size dosimeter showed the quenching effect in these three types of particle irradiation. The Ce:CaF2 small-size dosimeter showed the quenching effect only in carbon ion irradiation. The luminescence efficiencies of Eu:BaFBr were compared among these three charged particles. The quenching effect of Eu:BaFBr is independent of the irradiated particles.

DOI： 10.18494/SAM.2017.1626

Open Access