研究者詳細 - 吉橋　幸子

High heat removal technique for a lithium neutron generation target used for an accelerator-driven BNCT system

Yoshihashi, S; Tsuneyoshi, T; Tsuchida, K; Furuzawa, D; Honda, S; Watanabe, K; Yamazaki, A; Tsuji, Y; Hamaji, Y; Tokitani, M; Tamura, H; Sagara, A; Kiyanagi, Y; Uritani, A

JOURNAL OF INSTRUMENTATION 16 巻 ( 4 ) 2021年4月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Instrumentation

Accelerator-driven neutron sources have been developed worldwide for boron neutron capture therapy (BNCT) instead of nuclear reactors. Nagoya University is currently developing a compact DC accelerator driven BNCT system using a sealed lithium (Li) target. The target receives a high heat load by a proton beam, and the heat then requires efficient removal. This study developed a high-efficiency heat removal technique that uses V-shaped staggered ribs on the heat removal side of the flow channels. We performed experiments using an electron beam to confirm the technique performance. The results showed double the heat removal performance compared to the smooth surface channel. The value expected to sufficiently remove 6.6 MW/m2 of heat load provided by the proton beam at the Nagoya University neutron source for BNCT.

DOI： 10.1088/1748-0221/16/04/P04016

Neutron flux distributions in the Large Helical Device torus hall evaluated by an imaging plate technique in the first campaign of the deuterium plasma experiment Open Access

Kobayashi, M; Tanaka, T; Nishitani, T; Ogawa, K; Isobe, M; Motojima, G; Kato, A; Yoshihashi, S; Osakabe, M

NUCLEAR FUSION 59 巻 ( 12 ) 2019年12月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Nuclear Fusion

The global flux distributions for thermal, epithermal and fast neutrons in the torus hall of large fusion devices were experimentally evaluated for the first time in the Large Helical Device (LHD) using the activation foil method measured by the imaging plate and high-purity germanium detector. It turned out that the thermal neutrons were effectively absorbed by borated polyethylene blocks placed beneath the LHD. This should reduce the radioactivity of the floor and would be beneficial in maintaining a good environment for radiation workers. Uniform distributions of epithermal and fast neutrons were observed near the LHD. In particular, the significant decrease in fast neutron flux with increasing distance from the LHD, due to the fast energy loss of fast neutrons, was observed. The neutron flux distribution measurement, with rough energy discrimination based on the threshold energy of the neutron activation foil, allows us to estimate the spatial radiation dose rate, as well as the radioactivity in components in the torus hall. The prediction of the radioactivity in the concrete floor indicated that radioactive isotope 55Fe will be a dominant source of radioactivity in the concrete after the nine-year deuterium experiment campaign finishes.

DOI： 10.1088/1741-4326/ab3d14

Measurement of neutron spectrum using activation method in deuterium plasma experiment at LHD Open Access

Tanaka, T; Yoshihashi, S; Kobayashi, M; Uritani, A; Watanabe, K; Yamazaki, A; Nishitani, T; Ogawa, K; Isobe, M

FUSION ENGINEERING AND DESIGN 146 巻頁： 496 - 499 2019年9月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Fusion Engineering and Design

In the Large Helical Device (LHD) of the National Institute for Fusion Science, the experiments using deuterium plasma were performed from March 2017. Neutrons with the energy of 2.45 MeV are generated by d (d, n) 3He reactions. The evaluation of the neutron flux in the torus hall as well as the LHD vessel is very important for designing the decommissioning of the LHD in the future, and the radiation shielding for workers and components around LHD. In this study, we performed the activation experiments using multiple activation foils to obtain a neutron spectrum in the vacuum vessel of the LHD. The reaction rate of each activation foil was generally consistent with the calculation result by MCNP6. As a result of the unfolding with SAND-II code, we experimentally obtained the neutron spectrum in the vacuum vessel of the LHD for the first time.

DOI： 10.1016/j.fusengdes.2019.01.005

Effect of neutron beam properties on dose distributions in a water phantom for boron neutron capture therapy Open Access

Ishikawa, A; Tanaka, H; Nakamura, S; Kumada, H; Sakurai, Y; Watanabe, K; Yoshihashi, S; Tanagami, Y; Uritani, A; Kiyanagi, Y

JOURNAL OF RADIATION RESEARCH 65 巻 ( 6 ) 頁： 765 - 775 2024年10月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of radiation research

From the viewpoints of the advantage depths (ADs), peak tumor dose and skin dose, we evaluated the effect on the dose distribution of neutron beam properties, namely the ratio between thermal and epithermal neutron fluxes (thermal/epithermal ratio), fast neutron component and γ-ray component. Several parameter surveys were conducted with respect to the beam properties of neutron sources for boron neutron capture therapy assuming boronophenylalanine as the boron agent using our dose calculation tool, called SiDE. The ADs decreased by 3% at a thermal/epithermal ratio of 20-30% compared with the current recommendation of 5%. The skin dose increased with the increasing thermal/epithermal ratio, reaching a restricted value of 14 Gyeq at a thermal/epithermal ratio of 48%. The fast neutron component was modified using two different models, namely the 'linear model', in which the fast neutron intensity decreases log-linearly with the increasing neutron energy, and the 'moderator thickness (MT) model', in which the fast neutron component is varied by adjusting the MT in a virtual beam shaping assembly. Although a higher fast neutron component indicated a higher skin dose, the increment was <10% at a fast neutron component of <1 × 10-12 Gy cm2 for both models. Furthermore, in the MT model, the epithermal neutron intensity at a fast neutron component of 6.8 × 10-13 Gy cm2 was 41% higher compared with that of 2 × 10-13 Gy cm2. The γ-ray component also caused no significant disadvantages up to several times larger compared with the current recommendation.

DOI： 10.1093/jrr/rrae076

Simultaneous measurements for fast neutron flux and tritium production rate using pulse shape discrimination and single crystal CVD diamond detector Open Access

Kobayashi, MI; Yoshihashi, S; Ogawa, K; Isobe, M; Aso, T; Hara, M; Sangaroon, S; Tamaki, S; Murata, I; Toyama, S; Miwa, M; Matsuyama, S; Osakabe, M

NUCLEAR FUSION 64 巻 ( 6 ) 2024年6月

掲載種別：研究論文（学術雑誌）出版者・発行元：Nuclear Fusion

This paper presents the development of a simultaneous measurement method for fast neutron energy spectra and tritium production rates within mixed radiation fields using a single crystal chemical vapour deposition diamond detector combined with a lithium fluoride (LiF) foil. The method involves the separation of pulses with rectangular shapes and the determination of the depth position within the single crystal diamond (SCD) struck by fast neutrons or nuclear reaction products including recoil tritons from the LiF foil based on pulse width, extracting pulse events occurred at the specific bulk region and the surface region of the SCD. Subsequently, unfolding techniques were employed to analyse the energy deposition spectrum of pulses at the specific bulk region which are induced only by fast neutrons, allowing the deduction of the fast neutron energy spectrum. To evaluate the tritium production rate, the energy deposition spectrum of pulses from events occurring at the SCD surface facing the LiF foil was analysed. By estimating the energy deposition spectrum solely induced by fast neutrons striking the SCD surface and subtracting it from the energy deposition spectrum of events at the SCD surface, the contribution of energetic ions, such as recoil tritons generated by the 6Li(n,α)3H reaction in the LiF foil, was determined. The fast neutron flux and tritium production rate obtained through this study were consistent with particle transport calculations, demonstrating the successful development of a method suitable for performance testing of fusion reactor blankets.

DOI： 10.1088/1741-4326/ad3f2e

Estimation of nuclear properties in a deuteron-lithium target using JENDL/ DEU-2020 for IFMIF and similar irradiation facilities

Nishitani, T; Yoshihashi, S; Tanagami, Y; Amano, S; Uritani, A; Kwon, S; Kondo, K; Kumagai, K; Ochiai, K; Sato, S

FUSION ENGINEERING AND DESIGN 202 巻 2024年5月

掲載種別：研究論文（学術雑誌）出版者・発行元：Fusion Engineering and Design

An accelerator-based neutron source powered by deuteron–Li (d–Li) reactions is among the most promising neutron sources for fusion materials irradiation facilities, such as IFMIF, IFMIF-DONES, and A-FNS. The yield estimation of neutrons and other particles is critical to the design of these facilities. Presently, the McDelicious code is employed for the aforementioned yield estimations, although it is not an open code. Recently, a deuteron-induced reaction library, JENDL/DEU-2020, was released by the Japan Atomic Energy Agency. Thus, employing benchmark tests, such as the Particle and Heavy Ion Transport code System (PHITS) + JENDL/DEU-2020, Monte Carlo N-Particle + JENDL/DEU-2020, and McDelicious, we confirm that PHITS (or Monte Carlo N-Particle (MCNP)) + JENDL/DEU-2020 effectively reproduces the experimental data and McDelicious results. We apply PHITS + JENDL/DEU-2020 to the yield estimations of the neutron, gamma, and charged particles in a Li target and to the yield estimation of the charged particles in the target backplate for A-FNS. The estimated production rates of tritium and 7Be during the continuous operation using a deuteron beam of 40 MeV and 125 mA are 1.4 × 1016 atoms/s (2.3 g/FPY) and 5.9 × 1014 atoms/s (0.21 g/FPY), respectively, and the estimated production rates of He and H in the target backplate for A-FNS are 3.2 × 102 and 1.8 × 103 appm/FPY, respectively.

DOI： 10.1016/j.fusengdes.2024.114320

Application of a single crystal CVD diamond detector for fast neutron measurement in high dose and mixed radiation fields

Makoto I. Kobayashi, Sachiko Yoshihashi, Kunihiro Ogawa, Mitsutaka Isobe, Tsukasa Aso, Masanori Hara, Siriyaporn Sangaroon, Shingo Tamaki, Isao Murata, Masaki Osakabe

2024 IEEE International Conference on Consumer Electronics (ICCE) 頁： 1 - 4 2024年1月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：IEEE

This paper presents the method to evaluate the fast neutron energy spectrum under mixed radiation field using the single crystal CVD diamond detector. The pulse shape discrimination based on the shape and width of the pulse was applied to extract the event in which fast neutron hits at a specific depth of the single crystal diamond. Unfolding of the measured energy deposition spectrum induced by extracted pulses could deduce the neutron energy spectrum. An experiment using 14.1 MeV mono-energetic neutron source demonstrated the reliable capability of this method to evaluate the neutron energy spectrum quantitatively.

DOI： 10.1109/icce59016.2024.10444274

Application of a Single-Crystal CVD Diamond Detector for Fast Neutron Measurement in High Dose and Mixed Radiation Fields

Kobayashi, MI; Yoshihashi, S; Ogawa, K; Isobe, M; Aso, T; Hara, M; Sangaroon, S; Kusaka, S; Tamaki, S; Murata, I; Toyama, S; Miwa, M; Matsuyama, S; Osakabe, M

IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT 73 巻 2024年

掲載種別：研究論文（学術雑誌）出版者・発行元：IEEE Transactions on Instrumentation and Measurement

This article presents the method to evaluate the fast neutron energy spectrum using the single-crystal chemical vapor deposition (CVD) diamond detector to be applicable on the radiation monitoring in advanced scientific/engineering systems usually characterized with mixed and high-dose radiation field. The pulse shape discrimination (PSD) based on the shape and the width of a pulse was applied to extract events, in which fast neutron hits at the specific depth of the single-crystal diamond. Unfolding of the measured spectrum for extracted pulses could deduce the neutron energy spectrum. Experiments using monoenergetic neutron sources demonstrated the reliable capability of this method to evaluate the neutron energy spectrum quantitatively.

DOI： 10.1109/TIM.2024.3481590

Precise thermoluminescence glow curve analysis of BeO ceramic plates with slow heating rates

Sasaki, E; Sugioka, N; Chang, WS; Matsumoto, S; Negishi, T; Nagasaka, K; Yoshihashi, S; Uritani, A; Watanabe, K; Okada, G; Koba, Y; Shinsho, K

JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS 34 巻 ( 31 ) 2023年11月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Materials Science: Materials in Electronics

The glow curve components and thermoluminescence (TL) parameters of BeO ceramics plates with high bioequivalence were analyzed using extremely slow heating rates. Thermalox 995 was used as the BeO ceramic plates, which is a material with a BeO content of 99.5% or higher. The size of the plates was 10 × 10 × 0.7 mm3 with a density of 2.85 g/cm3, and an effective atomic number of 7.13. A linear accelerator was used for irradiation of the BeO plates at 5 Gy of 6 MV X-rays. After irradiation, the TL glow curve was measured using an in-house developed measurement instrument; the TL intensity was recorded from 50 to 400 °C with heating rates of 0.133, 0.05, and 0.005 °C/s used in three patterns. General-order kinetics were used for the theoretical analysis, which takes recapture into account. After irradiation, post-annealing was performed in the range of 50 to 350 °C at 50 °C intervals, and component analysis of the glow curves was also performed. The TL parameters were calculated from glow curves measured up to a heating rate that was three orders of magnitude slower than that previously measured. The activation energy and frequency factor for the main glow component at low temperatures were 1.15 eV and 1.11 × 1011/s, respectively, while those for the main glow component at high temperatures were 1.74 eV and 8.65 × 1013/s. The glow peak for the BeO ceramic plates were also determined have a low TL intensity component in close proximity to these two glow components. Furthermore, an increase in TL efficiency was observed when the glow curve was measured using an extremely slow heating rate. This may be due to a change of the carriers from TL-inactive when the glow curve is measured with a fast heating rate to TL-active with a longer thermal excitation time.

DOI： 10.1007/s10854-023-11378-7

Measurement of 6Li burn-up reaction rate using a single crystal CVD diamond detector under fast neutron irradiation environment

Kobayashi, MI; Yoshihashi, S; Ogawa, K; Isobe, M; Miwa, M; Toyama, S; Matsuyama, S; Osakabe, M

FUSION ENGINEERING AND DESIGN 193 巻 2023年8月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Fusion Engineering and Design

The study aimed to develop a technique for measuring the 6Li burn-up rate using a single crystal diamond (SCD) detector (SDD) made by chemical vapor deposition (CVD) with a thin lithium fluoride foil. The method relied on pulse shape discrimination (PSD) to separate pulses by nuclear reaction products of 6Li from pulses due to fast neutrons and gamma-rays. By applying the PSD method, the rectangular shape pulses induced by events occurred at the specific depth positions of the SCD, i.e., the incident surface, the ballistic center region (BCR), and the rear surface, were extracted. Thereafter, pulses occurred each specific depth position of the SCD were discriminated according to the pulse width. Due to a short range of nuclear reaction products in the SCD, pulses at the incident surface should be induced by both fast neutrons and nuclear reaction products, although pulses at the BCR are caused by fast neutron only. The study demonstrated that quantitative measurements of nuclear reaction products in the 6Li burn-up reaction under fast neutron irradiation can be achieved using only one SDD by analyzing event rates at the incident surface and in the BCR region.

DOI： 10.1016/j.fusengdes.2023.113799

(12)光ファイバ型中性子検出器を用いた原子炉特性の計測

渡辺賢一, 吉橋幸子, 石川諒尚, 若林源一郎

近畿大学原子炉利用共同研究等経過報告書令和3年度頁： 61 - 64 2023年3月

Neutron/γ-ray discrimination based on the property and thickness controls of scintillators using Li glass and LiCAF (Ce) in a γ-ray field 査読有り

Kaburagi M., Shimazoe K., Terasaka Y., Tomita H., Yoshihashi S., Yamazaki A., Uritani A., Takahashi H.

Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 1046 巻 2023年1月

Neutron/y-ray discrimination based on the property and thickness controls of scintillators using Li glass and LiCAF (Ce) in a y-ray field 査読有り

Kaburagi Masaaki, Shimazoe Kenji, Terasaka Yuta, Tomita Hideki, Yoshihashi Sachiko, Yamazaki Atsushi, Uritani Akira, Takahashi Hiroyuki

NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT 1046 巻 2023年1月

Measurements of γ-rays and neutrons in BNCT irradiation field using thermoluminescent phosphor

Shinsho, K; Oh, R; Tanaka, M; Sugioka, N; Tanaka, H; Wakabayashi, G; Takata, T; Chang, WS; Matsumoto, S; Okada, G; Sugawara, S; Sasaki, E; Watanabe, K; Koba, Y; Nagasaka, K; Yoshihashi, S; Uritani, A; Negishi, T

JAPANESE JOURNAL OF APPLIED PHYSICS 62 巻 ( 1 ) 2023年1月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Japanese Journal of Applied Physics

Boron neutron capture therapy (BNCT) is an innovative cancer therapy that selectively destroys only cancer cells by utilizing the reaction between boron agents, which selectively accumulate in cancer cells, and neutron beams. However, the irradiation field in BNCT is a mixture of multiple radiation types, making accurate dose evaluation difficult. For dose evaluation in cancer tissue, which is particularly important, it is essential to discriminate between neutrons and γ-rays mixed in the BNCT irradiation field and to measure them correctly. In this paper, we introduce a new method for selective measurement of neutrons and γ-rays using a thermoluminescent phosphor, which is expected to be a promising method for improving the accuracy of dose evaluations.

DOI： 10.35848/1347-4065/ac971e

Evaluation of heat removal performance of a sealed Li target for an accelerator-driven neutron source of Boron Neutron Capture Therapy at Nagoya University

Honda, S; Yoshihashi, S; Hamaji, Y; Shen, JJ; Tsuchida, K; Nishitani, T; Kiyanagi, Y; Tsurita, Y; Watanabe, K; Yamazaki, A; Uritani, A

NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT 1042 巻 2022年11月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

An accelerator-driven neutron source has been developed in Nagoya University for boron neutron capture therapy using a new concept of thick lithium (Li) target in which protons are stopped in a Li layer. A sealed Li target developed consists of a Li sheet placed on a copper (Cu) base plate equipped with water-cooled channels and a titanium (Ti) foil seal to cover Li surface. The proton beam injected into the target is produced through the proton–Dynamitron accelerator (IBA) with a maximum energy of 2.8 MeV and a current of 15 mA. The results of our previous study confirmed that the target was not damaged when irradiated with an acceleration energy of 1.8 MeV and a current of 0.5 mA (heat input of 4.6 MW/m2). To keep the soundness of the target up to 6–7 MW/m2, it is considered to be essential to improve the bonding between the Ti foil and Li interface, which will contribute the heat removal. It was suggested from our previous experiences that the bonding property may be improved by forming a Cu–Li alloy at the Ti–Li interface. In this paper, we evaluate the heat removal performance of a sealed Li target with Cu–Li alloy formation to improve the target durability. The sealed Li target was produced using a “Cu-coated pure Ti foil”, in which Cu was deposited on the surface of a Ti foil with a thickness of 0.2μm. The use of Cu-coated pure Ti foil actively forms Cu–Li alloys at the Ti–Li interface. For comparison, sealed Li targets were produced with pure Ti foil, and irradiation tests were conducted on each target. The heat removal performance was evaluated by electron beam irradiation using the active cooling teststand 2 (ACT2), a high heat flux test facility, and proton beam irradiation using the Dynamitron accelerator. We obtain a result that the Cu-coated pure Ti foil-sealed Li target has a heat removal capacity of 11 MW/m2, about five times higher than that of the pure Ti foil-sealed Li target. This confirmed that the Cu–Li alloy contributed to the improvement of the heat removal performance. For the proton beam irradiation test, a Cu-coated pure Ti foil target was produced and irradiated for 26 h at an acceleration energy of 1.8 MeV and an average current of 3.5 mA, where no neutrons were generated. The tests confirmed that the Cu-coated pure Ti foil target could withstand 26 h of irradiation at a heat input of 9.0 MW/m2. About anticipated degradation of the heat removal performance due to stopping the protons in the Li layer, no change was observed during this long irradiation test, in which 2.15 × 1024 protons were injected into the Li layer. Although further long-time irradiation test will be needed in the future, at present we have confirmed that there is no problem with stopping protons in the Li layer.

DOI： 10.1016/j.nima.2022.167414

γ-Ray measurements in boron neutron capture therapy using BeO ceramic thermoluminescence dosimeter

Tanaka, M; Oh, R; Sugioka, N; Tanaka, H; Takata, T; Wakabayashi, G; Sugawara, S; Watanabe, K; Uritani, A; Yoshihashi, S; Nagasaka, K; Okada, G; Negishi, T; Shinsho, K

JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS 33 巻 ( 25 ) 頁： 20271 - 20279 2022年9月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Materials Science: Materials in Electronics

In boron neutron capture therapy (BNCT), neutrons and γ-rays cause different biological effects, and it is necessary to discriminate between them for treatment planning and periodic inspections. Currently, the BeO powder thermoluminescence dosimeter (BeO powder TLD) is used for γ-ray dosimetry in mixed neutron and γ-ray fields due to the small capture cross section for neutrons, but correction is required because of the effects of neutron-induced activation. Besides, sales of BeO powder TLDs have been discontinued because the highly toxic BeO is readily dispersed when the detector is damaged. Therefore, the development of alternative replacement technologies for BeO powder TLDs that are not affected by neutrons is an important issue. In this study, we investigated the measurement of the γ-ray dose during BNCT using a BeO ceramic TLD, whereby the BeO was not released into the air. After 5, 15, 30, and 60 min of irradiation using the Kyoto University Research Reactor, the amount of thermoluminescence (TL) from the BeO ceramic TLD was shown to increase with irradiation time. In addition, the γ-ray dose, which was derived by converting the amount of TL to the dose, showed excellent proportionality to the irradiation time and was found to be comparable to the γ-ray dose measured with a BeO powder TLD. These results demonstrated that the BeO ceramic TLD can selectively measure only the γ-ray dose without influence by neutrons. Thus, our approach represents a new γ-ray dose measurement strategy that does not require correction for the contribution from thermal neutrons.

DOI： 10.1007/s10854-022-08843-0

Neutronics Analyses of the Radiation Field at the Accelerator-Based Neutron Source of Nagoya University for the BNCT Study Open Access

Nishitani, T; Yoshihashi, S; Tanagami, Y; Tsuchida, K; Honda, S; Yamazaki, A; Watanabe, K; Kiyanagi, Y; Uritani, A

JOURNAL OF NUCLEAR ENGINEERING 3 巻 ( 3 ) 頁： 222 - 232 2022年9月

掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Nuclear Engineering

The Nagoya University Accelerator-driven Neutron Source (NUANS) is an accelerator-based neutron source by 7Li(p,n)7Be reaction with a 2.8 MeV proton beam up to 15 mA. The fast neutrons are moderated and shaped to beam with a Beam Shaping Assembly (BSA). NUANS is aiming at the basic study of the Boron Neutron Capture Therapy (BNCT) such as an in vitro cell-based irradiation experiment using a water phantom. Moreover, the BSA is developed as a prototype of one for human treatment. We have evaluated the radiation field of NUANS by a Monte Carlo code PHITS. It is confirmed that the radiation characteristics at the BNCT outlet meet the requirement of IAEA TECDOC-1223. Additionally, the radiation field in the water phantom located just in front of the BSA outlet is calculated. In the in vitro irradiation experiment, the boron dose of 30 Gy-eq, which is the dose to kill tumor cells, is expected for 20 min of irradiation at the beam current of 15 mA.

DOI： 10.3390/jne3030012

Development of a simple calculation tool of dose distributions in a phantom for boron neutron capture therapy Open Access

Evaluation of Induced Radioactivity Generated during LHD Deuterium Plasma Experiments*) Open Access

Yoshihashi, S; Yamada, H; Kobayashi, M; Nishitani, T; Yamazaki, A; Isobe, M; Ogawa, K; Uritani, A

PLASMA AND FUSION RESEARCH 17 巻 ( 0 ) 頁： 2405096 - 2405096 2022年8月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：一般社団法人プラズマ・核融合学会

Neutrons are generated in a fusion plasma and induce various radionuclides via a nuclear reaction with fusion reactor materials. Evaluating the kinds of nuclide and the amount of induced radioactivity is important for decommissioning planning and regular maintenance. In this study, we verified a long-term prediction model of induced radioactivity in the large helical device (LHD) model by comparing induced radioactivity generated during deuterium plasma experiments in LHD with results calculated using a high-energy particle-induced radioactivity code. The metals employed for activation were SUS316L, Co, Mo, and Ni. During the deuterium plasma experiments, these materials were placed on an 8-O port of the LHD, and the induced radioactivity was measured weekly. To computed induced radioactivity using DCHAIN-SP, the neutron energy spectrum was computed using the LHD model with the Monte-Carlo simulation code PHITS. Although the calculated and measured radioactivity of 58Co and 54Mo agreed well, the calculated values of 60Co and 99Mo were underestimated. However, low-energy components could be improved by incorporating peripheral devices into the LHD model, resulting in more accurate radioactivity predictions

DOI： 10.1585/pfr.17.2405096

Ishikawa, A; Watanabe, K; Yoshihashi, S; Sakurai, Y; Kumada, H; Tanaka, H; Uritani, A; Kiyanagi, Y

JAPANESE JOURNAL OF APPLIED PHYSICS 61 巻 ( 7 ) 2022年7月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Japanese Journal of Applied Physics

A simple dose calculation tool, SiDE, was developed for dose evaluation in a water phantom for boron neutron capture therapy, which makes the calculation time much shorter compared with the conventional particle transportation Monte Carlo codes and is applicable to any type of incident neutron spectra to the phantom. As the SiDE can not only calculate quantitatively the dose distribution in the phantom but also output dose indexes such as advantage depth and peak tumor dose, a comparison between different boron neutron capture therapy neutron sources can be easily performed. Consistency with a Monte Carlo transportation code was verified through comparison with the conventional dose calculation with the Particle and Heavy Ion Transport Code System, and the calculation time was nearly 1/90 in the SiDE. The dose distributions for a reactor and accelerator-based neutron sources were compared, and the differences were found to be small although large differences existed between the incident spectra.

DOI： 10.35848/1347-4065/ac7273

Thermal Neutron Measurement Capability of a Single Crystal CVD Diamond Detector near the Reactor Core Region of UTR-KINKI Open Access

Kobayashi, MI; Yoshihashi, S; Yamanishi, H; Sangaroon, S; Ogawa, K; Isobe, M; Uritani, A; Osakabe, M

PLASMA AND FUSION RESEARCH 17 巻 ( 0 ) 頁： 2405045 - 2405045 2022年6月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：一般社団法人プラズマ・核融合学会

Thermal neutron flux evaluation using a single crystal diamond detector (SDD) was carried out in the core region of the UTR-KINKI reactor where a mixed radiation field by thermal and fast neutrons and gamma-ray exists. The pulse shape discrimination method to extract pulses with a rectangular shape as well as a wide pulse-width was established to exclude pulses induced by gamma-rays. The SDD, using a 6LiF thermal neutron converter, is able to detect pulse events caused not only by fast neutrons but also by thermal neutrons through energy depositions into the diamond by energetic alpha and triton particles induced by thermal neutrons. Additionally, the SDD without the thermal neutron converter was used for the measurement of the energy deposition events only by fast neutrons. A comparison of the pulse counts of the SDD with or without the thermal neutron convertor deduced the energy deposition spectra by thermal neutrons. The thermal neutron flux in the core region of the UTR-KINKI reactor was evaluated to be 7.6 × 106 n cm−2 s−1 W−1 up to a reactor power of 1W.

DOI： 10.1585/pfr.17.2405045

A comprehensive evaluation of the thermal neutron detection efficiency by a single crystal CVD diamond detector with a LiF thermal neutron converter Open Access

Kobayashi, MI; Yoshihashi, S; Ogawa, K; Isobe, M; Sangaroon, S; Kamio, S; Fujiwara, Y; Osakabe, M

FUSION ENGINEERING AND DESIGN 179 巻 2022年6月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Fusion Engineering and Design

Thermal neutron detection efficiency of the single crystal CVD diamond detector (SDD) equipping 1.9 μm-thick 6LiF thermal neutron converter, which induces the energetic ions through the 6Li(n,α)3H reaction, was evaluated comprehensively using a charge-integral based pulse shape discrimination (PSD) method and radiation transport calculation by PHITS. The PSD method applied in this work successfully separated the pulses induced by energetic tritons, alpha particles and other types of radiation. The detection efficiency of tritons was consistent with the radiation transport calculation, although that of alpha particles was lower than the estimation. The overall thermal neutron detection efficiency was obtained by summing detection efficiencies of tritons and alpha particles. Approximately 29% of 6Li(n,α)3H reaction occurred in an effective 1.9 μm-thick 6LiF thermal neutron converter could be detectable as the pulses of tritons (∼ 73%) and alpha particles (23%).

DOI： 10.1016/j.fusengdes.2022.113117

Neutron yield calculation of p-Li thick target by using PHITS with JENDL-4.0/HE and ENDF/B-VII for BNCT application

Nishitani, T; Tanagami, Y; Yoshihashi, S; Tsuchida, K; Yamazaki, A; Uritani, A

JOURNAL OF NUCLEAR SCIENCE AND TECHNOLOGY 59 巻 ( 5 ) 頁： 605 - 613 2022年5月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Nuclear Science and Technology

The lithium thick target bombed with low-energy protons is one of the promising neutron sources for the Boron Neutron Capture Therapy (BNCT). The benchmark calculations of the neutron Thick Target Yield (TTY) of the lithium target are conducted by the Particle and Heavy Ion Transport Code System PHITS with ACE formatted files of JENDL-4.0/HE and ENDF/B-VII and the DROSG-2000 code for the incident proton energy of around 3 MeV. Also, neutron TTY of the lithium thick target with a titanium window is evaluated for the Nagoya University Accelerator-driven Neutron Source (NUANS). Finally, the TTY evaluated with PHITS is applied for the neuron transport calculation for the Beam Shaping Assembly (BSA) of NUANS. As a conclusion, it is considered that ENDF/B-VII is more feasible than JENDL-4.0/HE for the 7Li(p,n)7Be reaction around 3 MeV of the proton energy.

DOI： 10.1080/00223131.2021.1996297

Neutron yield calculation of thin and thick d-D targets by using PHITS with frag data table Open Access

Nishitani, T; Yoshihashi, S; Ogawa, K; Miwa, M; Matsuyama, S; Uritani, A

JOURNAL OF NUCLEAR SCIENCE AND TECHNOLOGY 59 巻 ( 4 ) 頁： 534 - 541 2022年4月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Nuclear Science and Technology

The D(d, n)3He reaction is one of the common monoenergetic neutron sources. We compile the Frag Data table of D(d, n)3He reaction from the literature as an external cross-section data for PHITS. We confirm the validity of the Frag Data table by the calculation of the total and angular neutron yield calculations for an ideal deuterium thin target. Finally, PHITS with the Frag Data table is applied to the angular neutron yield and spectrum calculations of the gas target and the deuterium-loaded titanium target of the Tohoku University Fast Neutron Laboratory.

DOI： 10.1080/00223131.2021.1981475

Evaluation of the thermal neutron sensitivity, output linearity, and gamma-ray response of optical fiber-based neutron detectors using Li-glass scintillator

Ishikawa, A; Watanabe, K; Yamazaki, A; Yoshihashi, S; Imai, S; Masuda, A; Matsumoto, T; Tanaka, H; Sakurai, Y; Nogami, M; Hitomi, K; Uritani, A; Harano, H

NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT 1025 巻 2022年2月

An optical fiber-based neutron detector can be used as a real-time neutron monitor for an intense neutron field. In this study, optical fiber-based neutron detectors were fabricated using Li-glass scintillator. The thermal neutron sensitivity, upper limit of the output linearity, and response to gamma rays from 60Co and Cd were evaluated. The thermal neutron sensitivity was proportional to the mass of the Li-glass scintillator, and the calibration factor was 2.06 × 10−6 and 3.18 × 10−6 cps/(n/cm 2/s)/μg for the lower-level discrimination of the peak and valley channel, respectively. The detector output linearity was confirmed to be up to nearly 2 Mcps. While evaluating the response to gamma rays, for both 60Co and Cd, the gamma-ray counting rate was found to be smaller than the uncertainty associated with counting statistics in most expected applications where the neutron counting rate was >1 kcps.

DOI： 10.1016/j.nima.2021.166074

First experimental verification of the neutron field of Nagoya University Accelerator-driven neutron source for boron neutron capture therapy Open Access

Benchmark Calculation of d-Li Thick Target Neutron Yield by JENDL/DEU-2020 for IFMIF and Similar Facilities Open Access

Nishitani, T; Yoshihashi, S; Kumagai, K; Kondo, K; Uritani, A

PLASMA AND FUSION RESEARCH 16 巻 ( 0 ) 頁： 1405104 - 1405104 2021年11月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：一般社団法人プラズマ・核融合学会

An accelerator-based neutron source using d-Li reactions is one of the most promising neutron sources for fusion material irradiation facilities such as IFMIF, where 40 MeV deuterons bombard a liquid lithium target. The neutron yield estimation including angular neutron spectra is one of the most important issues in the design of such irradiation facilities. Recently, JAEA released deuteron nuclear data of JENDL/DEU-2020 in ACE format file for Monte Carlo codes such as MCNP, and in Frag-Data format for the PHITS code. We carry out the benchmark calculations of d-Li neutron yield by using PHITS with Frag-Data, MCNP with JENDL/DEU-2020, and MCNP/PHITS with built-in nuclear reaction models. Those calculation results are compared with experimental data. It is confirmed that PHITS with Frag Data and MCNP with JENDL/DEU-2020 reproduce well the experimental data. Those are useful for the neutron yield estimation and also the irradiation field characterization of IFMIF and similar facilities

DOI： 10.1585/pfr.16.1405104

BeO光刺激蛍光体を用いたBNCT場でのガンマ線線量評価

渡辺賢一, 中村悟, 永坂光正, 山﨑淳, 吉橋幸子, 瓜谷章

応用物理学会学術講演会講演予稿集 2021.1 巻 ( 0 ) 頁： 576 - 576 2021年2月

BeO光刺激蛍光体を用いたBNCT場でのガンマ線線量評価

渡辺賢一, 中村悟, 永坂光正, 山﨑淳, 吉橋幸子, 瓜谷章

応用物理学会学術講演会講演予稿集 2021.1 巻 ( 0 ) 頁： 576 - 576 2021年2月

Watanabe, K; Yoshihashi, S; Ishikawa, A; Honda, S; Yamazaki, A; Tsurita, Y; Uritani, A; Tsuchida, K; Kiyanagi, Y

APPLIED RADIATION AND ISOTOPES 168 巻頁： 109553 2021年2月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Elsevier

As the commissioning phase of the Nagoya University Accelerator-driven Neutron Source for boron neutron capture therapy, in-phantom thermal neutron flux measurements were conducted using a small ⁶LiF/Eu:CaF₂ scintillator detector and activation foils. The spatial distribution of the measured thermal neutron flux agreed with the Monte Carlo simulation results. Based on this comparison, the free-in-air neutron spectrum, calculated at the exit aperture, was verified and the epithermal neutron flux, at a 0.25 mA proton current, was evaluated as (1.49 ± 0.10) × 10⁷ n/(cm2 s).

DOI： 10.1016/j.apradiso.2020.109553

Thermal neutron measurement by single crystal CVD diamond detector applied with the pulse shape discrimination during deuterium plasma experiment in LHD Open Access

Kobayashi, MI; Angelone, M; Yoshihashi, S; Ogawa, K; Isobe, M; Nishitani, T; Sangaroon, S; Kamio, S; Fujiwara, Y; Tsubouchi, T; Uritani, A; Sakama, M; Osakabe, M

FUSION ENGINEERING AND DESIGN 161 巻 2020年12月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Fusion Engineering and Design

The Pulse shape discrimination (PSD) technique for single crystal CVD diamond detector (SDD) was applied to the real-time thermal neutron measurement during the 3rd campaign of Deuterium-Deuterium (D-D) plasma experiment in the Large Helical Device (LHD). The PSD method is based upon the different shape of electrical pulses produced in diamond by gamma-ray (triangular-shaped pulse) and energetic ions (rectangular-shaped pulse), respectively. An improved PSD was developed which makes use of the full width at half maximum (FWHM) and the full width at 2/3 of the peak height (FW2/3 PH). These two parameters reflect the difference in the pulse shape produced by gamma-rays and energetic ions. The performance of this improved PSD technique was first tested irradiating the SDD by gamma-rays from 60Co and alphas from 241Am radiation sources, respectively. Then, using a 6LiF thermal neutron converter, a successful discrimination between gamma-rays and alpha particles and tritons generated by the 6Li(n,α)3H reaction induced by neutrons from 252Cf spontaneous fission neutron source was achieved. Thanks to this PSD processing technique, the thermal neutron detection efficiency increased about 1.7 times compared to previous measurements performed without the PSD technique. The real-time thermal neutron measurement by SDD with this enhanced PSD processing was also used during D-D plasma discharges in the Large Helical Device (LHD). It was found that both the time integrated counts and the time evolution count rate measured by the SDD reproduced well that of the fission chamber used as official LHD neutron monitor. The capability of the SDD detector using the PSD technique of precise real-time thermal neutron measurement in LHD was demonstrated.

DOI： 10.1016/j.fusengdes.2020.112063

In Vitro Studies to Define the Cell-Surface and Intracellular Targets of Polyarginine-Conjugated Sodium Borocaptate as a Potential Delivery Agent for Boron Neutron Capture Therapy Open Access

Fujimura, A; Yasui, S; Igawa, K; Ueda, A; Watanabe, K; Hanafusa, T; Ichikawa, Y; Yoshihashi, S; Tsuchida, K; Kamiya, A; Furuya, S

CELLS 9 巻 ( 10 ) 2020年10月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Cells

Boron neutron capture therapy (BNCT) requires pharmaceutical innovations and molecular-based evidence of effectiveness to become a standard cancer therapeutic in the future. Recently, in Japan, 4-borono-L-phenylalanine (BPA) was approved as a boron agent for BNCT against head and neck (H&N) cancers. H&N cancer appears to be a suitable target for BPA-BNCT, because the expression levels of L-type amino acid transporter 1 (LAT1), one of the amino acid transporters responsible for BPA uptake, are elevated in most cases of H&N cancer. However, in other types of cancer including malignant brain tumors, LAT1 is not always highly expressed. To expand the possibility of BNCT for these cases, we previously developed poly-arginine peptide (polyR)-conjugated mercaptoundecahydrododecaborate (BSH). PolyR confers the cell membrane permeability and tumor selectivity of BSH. However, the molecular determinants for the properties are not fully understood. In this present study, we have identified the cluster of differentiation 44 (CD44) protein and translational machinery proteins as a major cell surface target and intracellular targets of BSH-polyR, respectively. CD44, also known as a stem cell-associated maker in various types of cancer, is required for the cellular uptake of polyR-conjugated molecules. We showed that BSH-polyR was predominantly delivered to a CD44High cell population of cancer cells. Once delivered, BSH-polyR interacted with the translational machinery components, including the initiation factors, termination factors, and poly(A)-biding protein (PABP). As a proof of principle, we performed BSH-polyR-based BNCT against glioma stem-like cells and revealed that BSH-polyR successfully induced BNCT-dependent cell death specifically in CD44High cells. Bioinformatics analysis indicated that BSH-polyR would be suitable for certain types of malignant tumors. Our results shed light on the biochemical properties of BSH-polyR, which may further contribute to the therapeutic optimization of BSH-BNCT in the future.

DOI： 10.3390/cells9102149

Observation of neutron emission anisotropy by neutron activation measurement in beam-injected LHD deuterium plasmas Open Access

Sugiyama, S; Nishitani, T; Matsuura, H; Isobe, M; Ogawa, K; Tanaka, T; Yoshihashi, S; Uritani, A; Osakabe, M

NUCLEAR FUSION 60 巻 ( 7 ) 2020年7月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Nuclear Fusion

Neutron emission anisotropy caused by neutral beam injection was observed by the neutron activation measurement in deuterium plasmas confined in the Large Helical Device. The shot-integrated fast neutron flux was measured by the irradiation of activation foils at two irradiation ends located at different ports. The ratio of the flux at the outside horizontal port to that at the lower port was used as an index of neutron emission anisotropy. The dependence of the ratio on the direction of the neutral beam injection was confirmed by comparing cases of tangential, perpendicular and both tangential and perpendicular neutral beam injections. Neutron emission anisotropy was numerically evaluated assuming these three cases of neutral beam injection. The analysis of neutron emission anisotropy comprises the evaluation of the velocity distribution function of energetic deuterons following guiding-centre orbits, calculation of the double-differential emission spectrum of neutrons produced by the D(d,n) 3&rm He reaction and neutron transport calculation. The obtained numerical results are qualitatively consistent in the dependence of neutron emission anisotropy on the neutral-beam-injection direction with the observed experimental data.

DOI： 10.1088/1741-4326/ab90c9

A comparison between simulation and experimental results for depth profile of 6Li reaction rate in a water phantom of BNCT using a small 6Li-based scintillator neutron detector with an optical fiber

Ishikawa, A; Yamazaki, A; Watanabe, K; Yoshihashi, S; Uritani, A; Tsurita, Y; Tsuchida, K; Kiyanagi, Y

RADIATION MEASUREMENTS 133 巻 2020年4月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Radiation Measurements

BNCT is a radiation therapy using neutrons. For dosimetry in BNCT, it is important to evaluate the thermal neutron distribution in a water phantom irradiated with neutrons used in the therapy. We proposed application of a small 6Li-based scintillator neutron detector with an optical fiber into a comparison study between simulation and experimental results in BNCT. In this paper, we compared simulation and experimental results for depth profile of 6Li(n,α) reaction rate in a water phantom of BNCT using a developed small 6Li-based scintillator neutron detector. The experimental results well agreed with the simulation ones. However, we found that the self-shielding effect in the detector will be significant even for a small LiF/Eu:CaF2 eutectics scintillator having the mass of 100 μg. We concluded that we have to consider the self-shielding effect in the small 6Li-based scintillator neutron detector when comparing simulation and experimental results of the 6Li(n,α) reaction rate in a water phantom.

DOI： 10.1016/j.radmeas.2020.106270

Basic study on a LiF-Eu:CaF2 mixed powder neutron scintillator

Liガラスシンチレータを用いた光ファイバ型中性子検出器の出力線形性および放射線耐性

石川諒尚, 山﨑淳, 渡辺賢一, 吉橋幸子, 瓜谷章

応用物理学会学術講演会講演予稿集 2020.1 巻 ( 0 ) 頁： 555 - 555 2020年2月

Liガラスシンチレータを用いた光ファイバ型中性子検出器の出力線形性および放射線耐性

石川諒尚, 山﨑淳, 渡辺賢一, 吉橋幸子, 瓜谷章

応用物理学会学術講演会講演予稿集 2021.1 巻 ( 0 ) 頁： 555 - 55 2020年2月

Watanabe, K; Mitsuboshi, N; Ishikawa, A; Yamazaki, A; Yoshihashi, S; Uritani, A; Kawaguchi, N; Yanagida, T; Fukuda, K

NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT 954 巻 2020年2月

We developed a mixed powder neutron scintillator as a novel neutron detection material. Since LiF-Ag:ZnS mixed powder, which is a widely used mixed powder neutron scintillator, is opaque owing to the extremely high refractive index of Ag:ZnS, the scintillator thickness is limited. We proposed the use of LiF-Eu:CaF2 mixed powder, where both LiF and Eu:CaF2 have almost the same refractive index, as a roughly transparent mixed powder neutron scintillator. Although the just mixed LiF-Eu:CaF2 powder is opaque, it can become translucent by filling the gap in the powder with a liquid glass resin as a refractive index buffer. As a result, we observe a peak shape in the pulse height spectrum obtained from the LiF-Eu:CaF2 mixed powder scintillator when irradiating thermal neutrons.

DOI： 10.1016/j.nima.2018.09.079

Sensitivity and linearity of optical fiber-based neutron detectors using small 6Li-based scintillators

Ishikawa, A; Yamazaki, A; Watanabe, K; Yoshihashi, S; Uritani, A; Fukuda, K; Koike, A; Ogawara, R; Suda, M; Hamano, T

NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT 954 巻 2020年2月

We developed optical fiber-based neutron detectors that use small pieces of6Li-based scintillators, namely, Eu:LiCaAlF6 crystals and LiF/Eu:CaF2 eutectics. Considering that these elements have high light yields (more than 10,000 photons/neutron), they can produce pulse height spectra with clear peaks even when using optical fiber light guides. To adjust the neutron sensitivity, we controlled the amount of6Li in the scintillator. We fabricated three different detectors using Eu:LiCaAlF6 and LiF/Eu:CaF2 with various amounts of6Li and then evaluated the neutron sensitivity of each detector. This approach confirmed that there was a linear relationship between the neutron sensitivity and amount of6Li, thus implying that the6Li mass measured by a high-precision balance could be a good metric of neutron sensitivity. We also checked the linearity of the output of the detector at relatively high neutron fluxes by using an accelerator-based neutron source. Although the detectors showed saturation behavior at high count rate, we were able to cover a relatively wide dynamic range by combining multiple detectors using different amounts of6Li. After correcting for the pulse height distortion and count loss due to pile-up events, we were able to confirm the linearity of the detectors up to a count rates of 100 kcps.

DOI： 10.1016/j.nima.2018.11.120

Numerical Study of Turbulent Heat transfer enhancement in square-duct flow through of inline V-shaped discrete ribs

Yu Stu. S., Tsuneyoshi T., Hamaji Y., Yoshihashi S., Ito T., Tsuji Y.

The Proceedings of Conference of Tokai Branch 2020.69 巻 ( 0 ) 頁： 520 2020年

Design of Neutron Spectrum-Shaping Assembly Around the Pneumatic Tube-End in the LHD Torus Hall for the Medical Research Application Open Access

Kobayashi, MI; Ogawa, K; Isobe, M; Nishitani, T; Nishimura, T; Mukai, K; Yoshihashi, S; Osakabe, M

PLASMA AND FUSION RESEARCH 15 巻 ( 0 ) 頁： 2405043 - 2405043 2020年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：一般社団法人プラズマ・核融合学会

The designs of neutron spectrum-shaping assembly (NSSA) composed with various shielding materials with natural isotopic abundance were evaluated to construct the neutron field dominated with thermal neutron or epi-thermal neutron for the application of neutron filed in the torus hall of LHD toward the BNCT research. According to the neutron transport calculation by MCNP6, the fast neutron moderation efficiency was higher in polyethylene (PE) compared to lithium fluoride (LiF) and magnesium fluoride (MF), although LiF showed relatively large epi-thermal and thermal neutron absorption. This comparison showed that the thermal neutron field can be effectively achieved with using PE. For constructing the NSSA which can provide the neutron field dominated with epi-thermal neutron, several NSSA designs were evaluated with respect to fast neutron flux, epithermal neutron flux, and gamma-ray dose. The combination of MF, lead (Pb) and cadmium (Cd) can provide the good epi-thermal neutron field with the mitigations of fast neutron flux and gamma-ray dose, which is also suitable for BNCT research in the torus hall of LHD.

DOI： 10.1585/pfr.15.2405043

Development of Optical-fiber-based Neutron Detector Using Li glass Scintillator for an Intense Neutron Field Open Access

Ishikawa, A; Yamazaki, A; Watanabe, K; Yoshihashi, S; Uritani, A; Sakurai, Y; Tanaka, H; Ogawara, R; Suda, M; Hamano, T

SENSORS AND MATERIALS 32 巻 ( 4 ) 頁： 1489 - 1495 2020年

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Sensors and Materials

The development of a neutron detector for real-time measurements in an intense neutron field is desired. We are developing a quartz optical-fiber-based neutron detector as a real-time neutron monitor. Thus far, Eu:LiCaAlF6 crystals and LiF/Eu:CaF2 eutectics have been used as the scintillators of the quartz optical-fiber-based neutron detectors. These scintillators have high light yields, but relatively long decay time constants, which are the limiting factors for the dynamic range of optical-fiber-based neutron detectors. In this work, we applied a small Li glass scintillator to a quartz optical-fiber-based neutron detector using an optical fiber with high numerical aperture and a UV-curable resin with high transmittance. The fabricated detector showed a clear peak corresponding to neutron events in the pulse height distribution. The radiation resistance was evaluated and no deterioration was observed up to 2 × 1012 n/cm2. The detector output linearity was confirmed up to 450 kcps, which was about ten times larger than that of the detector using the conventional Eu:LiCaAlF6 or LiF/Eu:CaF2 scintillator.

DOI： 10.18494/SAM.2020.2748

波長分解中性子イメージングによるTlBrの結晶性評価

渡辺賢一, 松本伎朗, 人見啓太朗, 野上光博, 山﨑淳, 吉橋幸子, 瓜谷章

応用物理学会学術講演会講演予稿集 2019.2 巻 ( 0 ) 頁： 519 - 519 2019年9月

波長分解中性子イメージングによるTlBrの結晶性評価

渡辺賢一, 松本伎朗, 人見啓太朗, 野上光博, 山﨑淳, 吉橋幸子, 瓜谷章

応用物理学会学術講演会講演予稿集 2019.2 巻 ( 0 ) 頁： 519 - 519 2019年9月

Thermal neutron flux evaluation by a single crystal CVD diamond detector in LHD deuterium experiment Open Access

Kobayashi, M; Ogawa, K; Isobe, M; Nishitani, T; Kamio, S; Fujiwara, Y; Tsubouchi, T; Yoshihashi, S; Uritani, A; Sakama, M; Osakabe, M

JOURNAL OF INSTRUMENTATION 14 巻 ( 9 ) 2019年9月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Instrumentation

A single crystal CVD diamond detector (SDD) was installed in the torus hall of the Large Helical Device (LHD) to measure neutron during deuterium plasma operation. The LiF foil with 95.62% of 6Li isotope enrichment pasted on the detector was used as the thermal neutron convertor. The energetic ions of 2.0 MeV alpha and 2.7 MeV triton particles generated by the nuclear reaction of neutron with 6Li in LiF foil. Then, energetic ions deposited the energy into diamond, producing a signals in SDD. SDD were exposed to the neutron field in the torus hall of the LHD during the 2nd campaign of the deuterium experiment. The total charge in SDD during one plasma shot in LHD was linearly propotional to the neutron yield over 4 orders of magnitude. The energetic alpha and triton were separately measured by SDD with LiF with the thickness of 1.9 μm, although SDD with LiF with the thickness of 350 μm showed a broadened peak due to the large energy loss of energetic particles generated in the bulk of LiF. The modeling with MCNP and PHITS codes well interpreted the pulse height spectra for SDD with LiF with different thicknesses.

DOI： 10.1088/1748-0221/14/09/C09039

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 14 巻 ( 06 ) 頁： T06010 - T06010 2019年6月

中性子ブラッグエッジ解析コードRITSにおけるシングルエッジフィッティングの改良

大前良磨, 渡辺賢一, 瓜谷章, 山﨑淳, 吉橋幸子, 鬼柳善明, 佐藤博隆

応用物理学会学術講演会講演予稿集 2019.1 巻 ( 0 ) 頁： 561 - 561 2019年2月

光ファイバ型中性子検出器を用いたBNCT中性子場の計測

石川諒尚, 山﨑淳, 渡辺賢一, 吉橋幸子, 瓜谷章, 釣田幸雄, 土田一輝, 鬼柳善明

応用物理学会学術講演会講演予稿集 2019.1 巻 ( 0 ) 頁： 526 - 526 2019年2月

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 6 巻 ( 0 ) 頁： 122 - 125 2019年1月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：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 6 巻 ( 0 ) 頁： 238 - 242 2019年1月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：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 6 巻 ( 0 ) 頁： 58 - 62 2019年1月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：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 14 巻 ( 0 ) 頁： 3405162 - 3405162 2019年

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：一般社団法人プラズマ・核融合学会

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

流体工学部門講演会講演論文集 2019 巻 ( 0 ) 頁： OS8-07 - 7 2019年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：一般社団法人日本機械学会

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, M; Tanaka, T; Nishitani, T; Ogawa, K; Isobe, M; Kato, A; Saze, T; Yoshihashi, S; Osakabe, M

FUSION ENGINEERING AND DESIGN 137 巻頁： 191 - 195 2018年12月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Fusion Engineering and Design

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年11月

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

Nishitani, T; Ogawa, K; Isobe, M; Kawase, H; Pu, N; Kashchuk, Y; Krasilnikov, V; Jo, J; Cheon, M; Tanaka, T; Yoshihashi, S; Li, SY; Osakabe, M

FUSION ENGINEERING AND DESIGN 136 巻頁： 210 - 214 2018年11月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Fusion Engineering and Design

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, M; Ogawa, K; Nishitani, T; Miyake, H; Kobuchi, T; Pu, N; Kawase, H; Takada, E; Tanaka, T; Li, SY; Yoshihashi, S; Uritani, A; Jo, J; Murakami, S; Osakabe, M

IEEE TRANSACTIONS ON PLASMA SCIENCE 46 巻 ( 6 ) 頁： 2050 - 2058 2018年6月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：IEEE Transactions on Plasma Science

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

ダイバーシティってなに？

吉田浩子, 吉橋幸子

日本原子力学会誌ATOMOΣ 60 巻 ( 5 ) 頁： 303 - 306 2018年

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：一般社団法人日本原子力学会

ダイバーシティ(多様性)推進委員会は，男女のジェンダーのみならず，より多角的な視野から働きやすい社会(学会)，職場を目指す活動を進めていくため2017年に男女共同参画委員会から名称を変更した。日本原子力学会会員がダイバーシティについてどのくらい認識しており，何が問題となっているかを再確認し，より良い活動のための基礎情報とするため，2017年秋の大会においてダイバーシティ推進におけるアンケート調査を実施した。本稿では，そのアンケート結果の報告と今後，本委員会で取り組んでいきたい事項について報告する。

DOI： 10.3327/jaesjb.60.5_303

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

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, SY; Yoshihashi, S; Uritani, A

REVIEW OF SCIENTIFIC INSTRUMENTS 88 巻 ( 11 ) 頁： 113302 2017年11月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：AIP Publishing

<jats:p>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.</jats:p>

DOI： 10.1063/1.5009475

Matsuda, S; Kanemura, T; Kondo, H; Kaji, S; Okita, T; Yoshihashi, S; Hoashi, E; Horiike, H

FUSION ENGINEERING AND DESIGN 124 巻頁： 1096 - 1100 2017年11月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Fusion Engineering and Design

International Fusion Material Irradiation Facility (IFMIF) is the facility generating the high flux and high energy neutrons to develop fusion reactor materials. In IFMIF, high-speed liquid lithium (Li) jet is used as the target irradiated by deuteron beams. Since the Li jet must flow with high velocity for heat removal, it is important to research on the Li flow characteristics. These researches have been aimed toward the steady-state Li flow characteristics. On the other hand, in the actual IFMIF, it is also necessary to clarify transient flow characteristics at start and stop of the system for the operation. In this study, water experiment to obtain them at start and stop is thus conducted. Water can be substituted for liquid Li as the target, because the kinematic viscosity of the Li at operation temperature in IFMIF is nearly equal to that of water at normal temperature and pressure. Flow patterns of the water jet at test section which consists of a two-staged contraction nozzle, a vertical concave flow channel are observed by laser probe method and high-speed video camera. As a result, the flow pattern at start and stop was successfully observed. The flow at stop became stable by venting gas.

DOI： 10.1016/j.fusengdes.2017.03.111

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

光刺激蛍光体と光ファイバーを用いた小型線量計における消光現象の補正方法の検討

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, 歳籐利行, 柳田健之

応用物理学会学術講演会講演予稿集 2017.2 巻 ( 0 ) 頁： 453 - 453 2017年8月

Hirata, Y; Watanabe, K; Yoshihashi, S; Uritani, A; Koba, Y; Naruhiro, MI; Yanagida, T; Toshito, T; Fukuda, K

SENSORS AND MATERIALS 29 巻 ( 10 ) 頁： 1455 - 1464 2017年

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Sensors and Materials

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

The design of the beam line of the Nagoya University accelerator-driven neutron source

Ito I., Furusawa D., Hirota K., Ichikawa G., Iwashita Y., Kitaguchi M., Kiyanagi Y., Menjo Y., Miwata Y., Shimizu H.M., Tsuchida K., Tsuchikawa Y., Tsurita Y., Uritani A., Watanabe K., Yamagata Y., Yamazaki A., Yoshihashi S.

Proceedings of Science 2017-January 巻 2017年

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Proceedings of Science

The Nagoya University Accelerator driven Neutron Source (NUANS) are now constructing at main campus of Nagoya University. The electrostatic accelerator is used with the maximum proton energy and power of 2.8MeV, 15mA(42kW) respectively. Two neutron beam lines are planned at NUANS. The first beam line is dedicated to BNCT. The second beam line is designed for research and development of neutron devices and neutron imaging. The neutrons used for the 2nd beam line are generated by using the (p, n) reaction of beryllium. We designed a compact target station for the 2nd beam line with the dimension of 90cm×90cm×95cm by using radiation shielding simulation. We considered neutron beam extraction with the cross section of 10cm×10cm for radiography at the 2nd beam line. The neutron flux is expected to be about 104n cm-2s-1 with the energy less than 0.1 eV at the position of 2m from the neutron source. We also calculated the proton beam transport from the exit of the accelerator to the neutron production target of the 2nd beam line.