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975 results on '"Fujimoto, Yutaka"'

154. Effect of linear energy transfer on the scintillation properties of Ce:Gd3Al2Ga3O12

Author

Yanagida, Takayuki, Yagi, Hideki, Yanagitani, Takagimi, Fujimoto, Yutaka, Asai, Keisuke, Kurashima, Satoshi, Kimura, Atsushi, and Taguchi, Mitsumasa

Abstract

固体中の重イオンの飛跡に沿った高密度励起は長年の研究の焦点であり、発光測定によりそのダイナミクスが解析されてきた。近年、我々はシンチレータの励起状態ダイナミクスの解析を行い、発光の減衰におけるLET依存性を見出してきた。本研究では、γ線検出のためのシンチレータとして開発されており、高密度で高い発光収率を有するCe：Gd3Al2Ga3O12（GAGG）の発光特性のLET依存性を解析した。 イオンビーム照射における時間分解発光測定は、TIARA施設のAVFサイクロトロンを用いて行った。異なるLETにおけるGAGGの発光時間プロファイルは、20MeVのH +、50MeVのHe2 +、および220MeVのC5 +のパルスイオンビームを用いて得られた。 GAGGの発光の立ち上がり速度はLETが低いほど減少し、発光減衰速度はLET依存性がないことが分かった。 このGAGGの発光の立ち上がり速度は、発光中心であるCe 3+イオンへのエネルギー移動速度に対応すると考えられる。 GAGGへのイオンビーム照射におけるゆっくりとした発光の立ち上がりは、Ce 3+イオンへのエネルギー移動により複数の励起状態が競合して存在していることが考えられる。

Published
2019

184. Neutron-induced thermoluminescence of Dy3+-doped Li2O–Al2O3–B2O3 glasses.

Author

Yamaguchi, Hiroto, Koshimizu, Masanori, Komiya, Hajime, Kawamoto, Hiroki, Fujimoto, Yutaka, Wakabayashi, Genichiro, Nogami, Mitsuhiro, Hitomi, Keitaro, Watanabe, Kenichi, and Asai, Keisuke

Subjects
THERMAL neutrons, THERMOLUMINESCENCE, NEUTRON irradiation, NEUTRON counters, GLASS
Abstract

In this study, we fabricated Dy3+-doped Li2O–Al2O3–B2O3 glasses using 6Li or nLi and 10B or 11B (6Li–10B, 6Li–11B, nLi–10B, and nLi–11B glasses) to develop a new thermoluminescent material for neutron detection, and their thermoluminescence (TL) properties were investigated after X-ray and thermal neutron irradiation. TL glow peaks were observed at 370 K after X-ray irradiation, and the integral values of TL intensities from 350 to 390 K for 6Li–10B, 6Li–11B, nLi–10B, and nLi–11B glasses were similar, indicating that these glasses have similar sensitivities to X-rays. A TL glow peak was observed at 400 K after neutron irradiation, and the integral values of TL intensities from 380 to 420 K for 6Li–10B, 6Li–11B, and nLi–10B glasses were higher than those of the nLi–11B glass, indicating that γ-rays and high-energy particles generated in the 6Li(n, α)3H and 10B(n, α)7Li reactions efficiently induced TL. The TL intensity of the 6Li–11B glass was significantly higher than those of the other glasses and showed good linearity against the thermal neutron fluence in the range of 5 × 107–1011 neutrons cm−2. [ABSTRACT FROM AUTHOR]

Published
2022
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191. Neutron-induced thermoluminescence properties of Tb3+-doped CaO–Al2O3–B2O3 glasses

Author

KAWAMURA, Ichiro, KAWAMOTO, Hiroki, FUJIMOTO, Yutaka, KOSHIMIZU, Masanori, OKADA, Go, Koba, Yusuke, Ogawara, Ryo, Yanagida, Takayuki, Asai, Keisuke, Masanori, Koshimizu, Go, Okada, Yusuke, Koba, Ryo, Ogawara, Takayuki, Yanagida, and Keisuke, Asai

Subjects
Condensed Matter::Soft Condensed Matter, Astrophysics::High Energy Astrophysical Phenomena, Physics::Medical Physics, Nuclear Experiment, Condensed Matter::Disordered Systems and Neural Networks
Abstract

We fabricated neutron detection glasses, Tb3+-doped CaO­Al2O3­B2O3 glasses, including 10B-enriched (10B glass) and 11B-enriched (11B glass) glasses. The glasses were irradiated with X-rays, heavy particles, or neutrons and their thermoluminescence (TL) properties were investigated. The TL properties after X-ray or heavy particle irradiation were the same for the 10B and 11B glasses. Meanwhile, after neutron irradiation, the TL properties of the 10B and 11B glasses were significantly different. The TL intensity of the 10B glasses was higher than that of the 11B glasses, and the TL peak intensity of 10B (n, ¡) reaction had good linearity in the irradiation range of 109 ­1013 neutrons/cm2.

Published
2019

192. Neutron detection via thermoluminescence of Ce3+-doped CaO–Al2O3–B2O3 glass.

Author

Kawamura, Ichiro, Kawamoto, Hiroki, Kimura, Hiromi, Komiya, Hajime, Fujimoto, Yutaka, Koshimizu, Masanori, Okada, Go, Koba, Yusuke, Ogawara, Ryo, Suda, Mitsuru, Wakabayashi, Genichiro, Yanagida, Takayuki, and Asai, Keisuke

Subjects
NEUTRON counters, THERMOLUMINESCENCE, BORON isotopes, NEUTRON irradiation, GLASS, NEUTRONS, RADIATION
Abstract

For neutron detection applications, we have synthesised glass phosphor materials of Ce3+-doped CaO–Al2O3–B2O3 with consisting boron in two different forms of isotopes, enriched 10B and 11B, called 10B-glass and 11B-glass, respectively. For radiation detections, thermoluminescence (TL) properties of the glasses were investigated with X-ray, proton, and neutron irradiations. The TL properties of X-ray- and proton-irradiated 10B- and 11B-glasses were similar while the TL intensity of neutron-irradiated 10B-glass was much greater than that of 11B-glass. The TL of the 10B-glass was observed across the neutron fluence range of 107–1012 neutrons/cm2, and the intensity increased monotonically with neutron fluence. [ABSTRACT FROM AUTHOR]

Published
2022
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193. Photoluminescence and scintillation properties of Al(PO3)3–CsPO3–CsBr–CeBr3 glass scintillators.

Author

Nakabayashi, Yusuke, Fujimoto, Yutaka, Koshimizu, Masanori, and Asai, Keisuke

Subjects
SCINTILLATORS, NUCLEAR counters, PHOTOLUMINESCENCE, VISIBLE spectra, X-ray detection, DECAY constants
Abstract

Scintillators, which are widely used as radiation detectors, are phosphors that release absorbed ionizing radiation energy as ultraviolet or visible light. Inorganic glass scintillators have several advantages over inorganic crystal scintillators, such as ease of fabrication and low costs. However, unlike inorganic crystals, which can emit up to tens of thousands of photons/MeV, inorganic glasses exhibit less than several hundred photons/MeV in most cases. Here, we studied an inorganic glass scintillator that exhibits a light yield of 2700 photons/MeV, which exceeds those of previous inorganic glass scintillators with high light yields of approximately 2000 photons/MeV. The density of this material is 3.28 g/cm3, which is relatively high among glass scintillators. Moreover, a fast scintillation decay with a decay time constant of 30.0 ns was obtained and is attributed to the 5d–4f transition of Ce3+. Thus, this glass is suitable for gamma- and X-ray detection, thereby expanding the practical applicability of inorganic glass scintillators. [ABSTRACT FROM AUTHOR]

Published
2022
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200. Neutron detection via thermoluminescence of Ce3+-doped CaO–Al2O3–B2O3 glass

Author

Kawamura, Ichiro, Hiroki, Kawamoto, Kimura Hiromi, Kimura, Hiromi, Fujimoto, Yutaka, Masanori, Koshimizu, Go, Okada, Yusuke, Koba, Ryo, Ogawara, Mitsuru, Suda, Genichiro, Wakabayashi, Takayuki, Yanagida, Keisuke, Asai, and Hiromi, Kimura

Subjects
Astrophysics::High Energy Astrophysical Phenomena, Nuclear Theory, Physics::Medical Physics, Nuclear Experiment, Condensed Matter::Disordered Systems and Neural Networks
Abstract

For neutron detection applications, we have synthesised glass phosphor materials of Ce3+-doped CaO–Al2O3–B2O3 with consisting boron in two different forms of isotopes, enriched 10B and 11B, called 10B-glass and 11B-glass, respectively. For radiation detections, thermoluminescence (TL) properties of the glasses were investigated with X-ray, proton, and neutron irradiations. The TL properties of X-ray- and proton-irradiated 10B- and 11B-glasses were similar while the TL intensity of neutron-irradiated 10B-glass was much greater than that of 11B-glass. The TL of the 10B-glass was observed across the neutron fluence range of 107–1012 neutrons/cm2, and the intensity increased monotonically with neutron fluence.

Published
2020

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