Faculty Profiles - URITANI Akira

Presentations -

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炭素量の異なる鉄鋼材料のパルス中性子を用いた透過率測定とブラッグエッジ解析 International conference

磯野真理子、塩田佳徳、渡辺賢一、瓜谷章、鬼柳善明、田中眞奈子

日本中性子科学会第14回年会

Neutron Detection Property of Small Scintillators Dispersed in Transparent Resin (TRUST LiCAF)

A. Uritani, D. Sugimoto, T. Yamazaki, T. Mizukoshi, K. Watanabe, A. Yamazaki, K. Fukuda, S. Ishizu, N. Kawaguchi, Y. Fujimoto, K. Yanagida, A. Yoshikawa

Stereographic Backscattered X-Ray Tomography with Scanning Pencil-Beam for One-Sided Nondestructive Inspection International conference

T. Tohyama, A. Yamazaki, K. Watanabe, A. Uritani

IEEE NUCLEAR SCIENCE SYMPOSIUM

Event date： 2014.11

Language：English Presentation type：Poster presentation

Country：Japan

Routine maintenance and inspections for large size infrastructure, such as bridges and tunnels, are required due to aging degradation. The nondestructive internal inspection with imaging is quite useful for this purpose. Although the transmission X-ray imaging technique has high spatial resolution, it is unsuitable for large size structures because it is necessary to sandwich objects between an X-ray source and detectors. The backscattered X-ray imaging technique can be used for the internal visualization of large size structures because it can carry out an inspection from one-side of the object. However, it takes long time to obtain a tomographic image based on this technique. Therefore, we proposed a tomography technique based on backscattered X-ray, which is available for large size structures and reduces measurement time, as a one-sided inspection. The proposed system consists of a pencil-beam X-ray source, which can sweep an angle and slide a position, and the X-ray detectors which record the integrated quantity of the backscattered X-rays for every incident angles and source positions. The recorded values are indexes of the line integral of scattering cross section along the incident X-ray beam. Tomographic images can be acquired using image reconstruction procedures based on a stereographic technique. In this paper, we simulated the projection of backscattered X rays using the Monte Carlo simulation code EGS5 to confirm the principle of our tomographic imaging technique. We successfully demonstrated that the stereographic backscattered X-ray tomography was able to reconstruct the tomographic image of the object shape with one-sided inspection. In addition, we experimentally confirmed that a sufficient amount of backscattered X-ray can be acquired.

Characterization of Large Area Transparent RUbber SheeT (TRUST) LiCaAlF₆ Neutron Scintillator International conference

K. Watanabe, A. Yamazaki, D. Sugimoto, T. Yamazaki, A. Uritani, T. Iguchi, K. Fukuda, S. Ishidu, T. Yanagida, Y. Fujimoto

IEEE NUCLEAR SCIENCE SYMPOSIUM

Event date： 2014.11

Language：English Presentation type：Oral presentation (general)

Country：Japan

Alternatives of standard He-3 neutron detectors have been required to be developed because of the He-3 shortage. We are developing the Eu:LiCaAlF₆ scintillators as one of the candidates for an alternative of the He-3 detector. Although this scintillator has high light yield, it suffers from the interference of gamma rays due to its relatively low a/ß ratio. In addition, synthesis of large Eu:LiCaAlF₆ single crystals requires relatively long time and high cost. In order to solve these problems, we have developed a Transparent RUbber SheeT type Eu:LiCaAlF₆ (TRUST LiCAF) scintillator in which small pieces of Eu:LiCaAlF₆ scintillators are dispersed. The size of small pieces of Eu:LiCaAlF₆ crystals are controlled to be smaller than the ranges of fast electrons induced by gamma rays and larger than the ranges of alphas and tritons produced by ⁶Li(n,t) reaction. Consequently, the signal pulse height of gamma-ray induced events can be reduced smaller than that of neutron induced events. The size or area of this type of scintillator can easily be enlarged using a large size mold in the solidification process of the resin. In this paper we fabricated a relatively large size TRUST LiCAF scintillator and evaluated its basic performances. The TRUST LiCAF scintillator was directly mounted on the window of the photomultiplier tube. Gamma-ray induced events are almost completely eliminated by setting an adequate threshold level. Consequently, sufficiently low gamma-ray detection efficiency was confirmed with keeping adequate neutron detection efficiency.

Gamma-Ray Suppression with Pulse Shape Discrimination Technique for Transparent RUbber SheeT (TRUST) LiCaAlF₆ Neutron Scintillator with Wavelength-Shifting Fiber Readout International conference

T. Yamazaki, K. Watanabe, A. Yamazaki, D. Sugimoto, A. Uritani, T. Iguchi, K. Fukuda, S. Ishidu, T. Yanagida

IEEE NUCLEAR SCIENCE SYMPOSIUM

Event date： 2014.11

Language：English Presentation type：Poster presentation

Country：Japan

Alternatives to He-3 neutron detectors are required to be developed due to He-3 shortage problem and increase in demand for neutron detectors in security and scientific applications. We have, therefore, developed a Transparent RUbber SheeT type Eu:LiCaAlF₆ (TRUST LiCAF) neutron scintillator. This type of scintillator is made of a transparent rubber sheet in which a large number of small pieces of Eu:LiCaAlF6 scintillator are dispersed. In the TRUST LiCAF scintillator, pulse heights of gamma-ray induced events are suppressed and these events can easily be rejected with pulse height discrimination. In addition, this scintillator can easily be fabricated with large area. For large area scintillators, wavelength-shifting fiber (WLS) fiber readout is quite useful. In this paper, we evaluated the basic performance of the TRUST LiCAF scintillator with WLS fiber readout. WLS fibers were bundled in plate shape. The TRUST LiCAF scintillator with the size of 200x50x5 mm3 was mounted on the WLS fiber plate. Although the peak shape corresponding to the neutron absorption events can clearly be confirmed, gamma-ray induced events also have relatively high pulse heights. These events with relatively high pulse heights is considered to be events produced in the WLS fiber by interactions between gamma rays and the WLS fibers. The scintillation in the WLS fiber has shorter decay time of a few ns compared with the TRUST LiCAF scintillator whose decay time is a few µs. Fiber emission events can be clearly distinguished from TRUST LiCAF scintillator emission events by using the pulse shape discrimination technique. Consequently, gamma-ray detection efficiency can sufficiently be reduced with keeping adequate neutron detection efficiency.

Development of a Novel Neutron Energy Spectrometer Using Onion-like Multi-Shell Single Bonner Sphere International conference

K. Watanabe, M. Ushida, A. Yamazaki, A. Uritani, T. Iguchi, T. Ogata, T. Muramatsu

IEEE NUCLEAR SCIENCE SYMPOSIUM

Event date： 2014.11

Language：English Presentation type：Poster presentation

Country：Japan

In order to measure neutron energy spectra, the conventional Bonner Sphere Spectrometers (BSS) are widely used. The neutron spectrum can be derived by deconvolution procedures, which reconstruct the spectrum from several Bonner spheres outputs by using their response functions. In this spectrometer, since several measurements with different Bonner spheres are required, operators should bring these spheres many times to the measurement point where the radiation dose might be relatively high. In order to solve this disadvantage, a single Bonner sphere that utilizes difference in spatial distribution of the thermal neutrons in the sphere was proposed. Since the conventional single Bonner sphere spectrometers consist of some small thermal neutron detectors discretely arranged in the sphere or three one-dimensional position sensitive counters perpendicularly arranged, they have considerable directional dependence in the detector response. We have, therefore, proposed a novel neutron energy spectrometer using an onion-line single Bonner sphere, which has multiple sensitive spherical shells as the detector configuration without directional dependence. In this paper, in order to confirm the detector response of the proposed neutron spectrometer, the prototype detector with five sensitive layers was fabricated and basic experiments were carried out. The experimental results are consistent with the expected c simulated with Monte Carlo calculations. The count rates of outer layers increase and the rates of inner layers decrease compared with the direct irradiation condition in which the neutron spectrum is harder. We experimentally confirmed the detector response which reflects the neutron energy spectrum.

Study on Neutron Imaging Technique Using Transparent RUbber SheeT (TRUST) LiCaAlF₆ Neutron Scintillator International conference

D. Sugimoto, K. Watanabe, A. Yamazaki, T. Yamazaki, A. Uritani, T. Iguchi, K. Fukuda, S. Ishidzu, T. Yanagida

IEEE NUCLEAR SCIENCE SYMPOSIUM

Event date： 2014.11

Language：English Presentation type：Poster presentation

Country：Japan

We have developed Eu:LiCaAlF₆ (Eu:LiCAF) scintillators as a novel He-3 alternative neutron detector. Although this scintillator has various useful properties such as high neutron detection efficiency, high light yield, no hygroscopicity and high transparency, it suffers from the influence of gamma-ray due to its low a/ß ratio. In addition, single crystal scintillators are generally difficult to fabricate detectors with a large area of several tens of square centimeters. To overcome these difficulties, we proposed to disperse small pieces of Eu:LiCAF scintillators into a transparent rubber and form a rubber sheet type scintillator. This type of scintillator is referred to as a Transparent RUbber SheeT (TRUST) LiCAF scintillator. A small piece of Eu:LiCAF scintillator can selectively reject only gamma-ray events due to a difference between ranges of fast electrons induced by gamma rays and 6Li(n,t) reaction products. By dispersing small pieces of Eu:LiCAF crystals into a transparent rubber sheet, the neutron detection efficiency can increase with keeping the gamma-ray event suppression ability. Since a TRUST LiCAF scintillator can easily enlarged its area, a neutron imaging is one of the attractive applications. In this paper, we successfully demonstrate that the TRUST LiCAF scintillator can acquire neutron images. Under the current status, the spatial resolution is evaluated to be less than a few mm.

赤外発光シンチレータを用いた耐放射線性の高い放射線検出器の開発

熊谷洋祐，渡辺賢一，山崎　淳，瓜谷　章

第75回応用物理学会秋季学術講演会

透明樹脂型Eu:LiCaAlF₆シンチレータと波長シフトファイバ読出しを用いた大面積中性子検出器の開発

山﨑拓弥，杉本大，渡辺賢一，山﨑淳，瓜谷章，井口哲夫，福田健太郎，石津澄人，柳田健之

第75回応用物理学会秋季学術講演会

Eu:LiCaAlF₆分散樹脂型シンチレータの発光特性の評価

杉本大，山﨑拓弥，渡辺賢一，山﨑淳，瓜谷章，井口哲夫，福田健太郎，石津澄人，柳田健之

第75回応用物理学会秋季学術講演会

モンテカルロ計算に基づくヘリカル型核融合実験装置の中性子モニタに関する研究（2）モニタ設置位置の検討

仲野裕次，瓜谷章，渡辺賢一，山﨑淳，磯部光孝，小川国大

日本原子力学会 2014年秋の大会

LIBS を用いた固体表面水素分布測定法に関する研究

吉本久晃，瓜谷章，渡辺賢一，山﨑淳，井上龍夫

日本原子力学会 2014年秋の大会

後方散乱X 線断層撮像技術に関する研究

○遠山貴之，瓜谷章，渡辺賢一，山﨑淳，吉田迅

日本原子力学会 2014年秋の大会

Project of Electrostatic Accelerator-based BNCT System in Nagoya University

Yoshiaki KIYANAGI, Kazuki TSUCHIDA , Akira URITANI, Yuya KAWABATA, Atsushi YAMAZAKI, Menjo Yosuke, Takuya YAMAZAKI, Kenichi WATANABE, Katsuya HIROTA, Masaaki KITAGUCHI, Hirohiko SHIMIZU

Development of an accelerator-driven compact neutron source for BNCT in Nagoya University International conference

K. Tsuchida, Y. Kiyanagi, A. Uritani, K. Watanabe, H. Shimizu, K. Hirota, M. Kitaguchi

16th International Congress on Neutron Capture Therapy

Event date： 2014.6

Language：English Presentation type：Oral presentation (general)

Country：Finland

Development of an accelerator-driven compact neutron source has been started in Nagoya University for BNCT application based on a low-energy high-current DC accelerator, which has also extra possibilities of applications to fundamental physics experiments and industry uses.

Fundamental properties of Transparent RUbber SheeT (TRUST) LiCaAlF₆ neutron scintillator International conference

Dai Sugimoto, A. Uritani et al.

2014 Symposium on Radiation Measurements and Applications

Response evaluation of a small radiation detector using OSL with optical fiber readout to high energy carbon ions International conference

Dai Sugimoto, A. Uritani et al.

2014 Symposium on Radiation Measurements and Applications

Tomographic imaging from one-side using backscattered X-ray International conference

K. Watanabe, A. Uritani et al.

2014 Symposium on Radiation Measurements and Applications

Wavelength-shifting fiber signal readout from Transparent Rubber SheeT (TRUST) type LiCaAlF₆ neutron scintillator International conference

K. Watanabe, A. Uritani et al.

2014 Symposium on Radiation Measurements and Applications

Wide dynamic range neutron flux monitor having fast time response for the Large Helical Device International conference

M. Isobe, K. Ogawa, H. Miyake, H. Hayashi, T. Kobuchi, Y. Nakano, K. Watanabe, A. Uritani, T. Misawa, T. Nishitani, M. Tomitaka, T. Kumagai, Y. Mashiyama, D. Ito, S. Kono, M. Yamauchi and Y. Takeiri

20th Topical Conference on High-Temperature Plasma Diagnostics

Event date： 2014.6

Language：English Presentation type：Oral presentation (general)

Country：United States

A fast time response, wide dynamic range neutron flux monitor has been developed toward the LHD deuterium operation by using leading-edge signal processing technologies, providing maximum counting rate up to ~5×10⁹ (cps). Because a maximum total neutron emission rate over 1×10¹⁶ (n/s) is predicted in neutral beam-heated LHD plasmas, fast response and wide dynamic range capabilities of the system are essential. Preliminary tests have demonstrated successful performance as wide dynamic range monitor along the design.

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