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Journal Articles

Visualizing cation vacancies in Ce:Gd$$_{3}$$Al$$_{2}$$Ga$$_{3}$$O$$_{12}$$ scintillators by gamma-ray-induced positron annihilation lifetime spectroscopy

Fujimori, Kosuke*; Kitaura, Mamoru*; Taira, Yoshitaka*; Fujimoto, Masaki*; Zen, H.*; Watanabe, Shinta*; Kamada, Kei*; Okano, Yasuaki*; Kato, Masahiro*; Hosaka, Masahito*; et al.

Applied Physics Express, 13(8), p.085505_1 - 085505_4, 2020/08

 Times Cited Count:3 Percentile:37.21(Physics, Applied)

To clarify the existence of cation vacancies in Ce-doped Gd$$_{3}$$Al$$_{2}$$Ga$$_{3}$$O$$_{12}$$ (Ce:GAGG) scintillators, we performed gamma-ray-induced positron annihilation lifetime spectroscopy (GiPALS). GiPAL spectra of GAGG and Ce:GAGG comprised two exponential decay components, which were assigned to positron annihilation at bulk and defect states. By an analogy with Ce:Y$$_{3}$$Al$$_{5}$$O$$_{12}$$, the defect-related component was attributed to Al/Ga-O divacancy complexes. This component was weaker for Ce, Mg:GAGG, which correlated with the suppression of shallow electron traps responsible for phosphorescence. Oxygen vacancies were charge compensators for Al/Ga vacancies. The lifetime of the defect-related component was significantly changed by Mg co-doping. This was understood by considering aggregates of Mg$$^{2+}$$ ions at Al/Ga sites with oxygen vacancies, which resulted in the formation of vacancy clusters.

Journal Articles

Aiming at a nuclear data library leading the world; Nuclear data research activity and nuclear data division

Igashira, Masayuki*; Baba, Mamoru*; Watanabe, Yukinobu*; Katakura, Junichi; Suyama, Kenya

Nihon Genshiryoku Gakkai-Shi ATOMO$$Sigma$$, 51(4), p.290 - 293, 2009/04

The nuclear data library is required for the research and development of the nuclear energy. The requirements include not only safety improvements associated with high burnup of light water reactors, utilization of MOX fuels, and criticality safety control implementation of burnup credit and so on, but also research and development of innovative nuclear power system such as nuclear transmutation with the ADS; these requirements demand high precision data for the nuclear cross sections of minor actinides and fission product nuclides, and for the fission yields. The most important users of the nuclear data will still be those in the nuclear energy field. Moreover, for those users in the fields of radiation application and radiological engineering, nuclear data are required to be expanded in quantity and upgraded in quality. In the globalization trend of nuclear power industries, the international standard of nuclear data library is anticipated. In order to reflect the technology developed by Japan in the international standard, we should have our own nuclear data library leading the world.

Journal Articles

Design of the shift bump magnets for the beam injection of the 3-GeV RCS in J-PARC

Takayanagi, Tomohiro; Kamiya, Junichiro; Watanabe, Masao; Ueno, Tomoaki*; Yamazaki, Yoshishige; Irie, Yoshiro; Kishiro, Junichi; Sakai, Izumi*; Kawakubo, Toshimichi*; Tounosu, Shigeki*; et al.

IEEE Transactions on Applied Superconductivity, 16(2), p.1366 - 1369, 2006/06

 Times Cited Count:8 Percentile:44.7(Engineering, Electrical & Electronic)

The injection system of the 3-GeV RCS in J-PARC is composed of four main orbit bump magnets (shift bump) to merge the injection beam with the circulating beam. The magnetic field design and the structural analysis of the shift bump magnets have been performed using 3D magnetic and mechanical codes. In this paper, the design of the bending magnets is reported.

Journal Articles

Measurement of self-diffusion coefficients in Li ionic conductors by using the short-lived radiotracer of $$^8$$Li

Jeong, S.-C.*; Katayama, Ichiro*; Kawakami, Hirokane*; Watanabe, Yutaka*; Ishiyama, Hironobu*; Imai, Nobuaki*; Hirayama, Yoshikazu*; Miyatake, Hiroari; Sataka, Masao; Okayasu, Satoru; et al.

Journal of Phase Equilibria and Diffusion, 26(5), p.472 - 476, 2005/09

Authors developed a radiotracer method for diffusion studies in solids. The experimental test was performed by the measurement of the diffusion coefficients of Li in a sample of the compound $$beta$$LiAl using an $$alpha$$-emitting radiotracer of $$^8$$Li(T$$_{1/2}$$ = 0.84 s). It was found that the time-dependent yields of the alpha particles from the diffusing 8Li that was initially implanted in the sample could be used as a measure of the diffusivity of the tracer in a nondestructive way. The method was applied to measure the self-diffusion coefficients of Li in $$beta$$LiGa, and for investigating how the Li diffusion in the Li ionic conductors is affected by the concentration of atomic defects.

Journal Articles

Measurement of diffusion coefficients in solids by the short-lived radioactive beam of $$^{8}$$Li

Jeong, S.-C.*; Katayama, Ichiro*; Kawakami, Hirokane*; Watanabe, Yutaka*; Ishiyama, Hironobu*; Miyatake, Hiroari*; Sataka, Masao; Okayasu, Satoru; Sugai, Hiroyuki; Ichikawa, Shinichi; et al.

Nuclear Instruments and Methods in Physics Research B, 230(1-4), p.596 - 600, 2005/04

 Times Cited Count:6 Percentile:46.35(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Nuclear science and engineering expected in high-intensity Proton Accelerator facility (J-PARC)

Kiyanagi, Yoshiaki*; Nagamiya, Shoji*; Oyama, Yukio; Ikeda, Yujiro; Oigawa, Hiroyuki; Igashira, Masayuki*; Baba, Mamoru*; Iwasaki, Tomohiko*; Watanabe, Yukinobu*; Ishibashi, Kenji*

Nihon Genshiryoku Gakkai-Shi, 46(3), p.173 - 197, 2004/03

no abstracts in English

Journal Articles

Simulation study on the measurements of diffusion coefficients in solid materials by short-lived radiotracer beams

Jeong, S.-C.*; Katayama, Ichiro*; Kawakami, Hirokane*; Ishiyama, Hironobu*; Miyatake, Hiroari*; Sataka, Masao; Iwase, Akihiro; Okayasu, Satoru; Sugai, Hiroyuki; Ichikawa, Shinichi; et al.

Japanese Journal of Applied Physics, Part 1, 42(7A), p.4576 - 4583, 2003/07

no abstracts in English

Journal Articles

Simulation study on the measurements of diffusion coefficients in solid materials by short-lived radiotracer beams

Jeong, S.-C.*; Katayama, Ichiro*; Kawakami, Hirokane*; Ishiyama, Hironobu*; Miyatake, Hiroari*; Sataka, Masao; Iwase, Akihiro*; Okayasu, Satoru; Sugai, Hiroyuki; Ichikawa, Shinichi; et al.

Japanese Journal of Applied Physics, Part 1, 42(7A), p.4576 - 4583, 2003/07

 Times Cited Count:14 Percentile:51.25(Physics, Applied)

no abstracts in English

Journal Articles

Japanese evaluated nuclear data library version 3 revision-3; JENDL-3.3

Shibata, Keiichi; Kawano, Toshihiko*; Nakagawa, Tsuneo; Iwamoto, Osamu; Katakura, Junichi; Fukahori, Tokio; Chiba, Satoshi; Hasegawa, Akira; Murata, Toru*; Matsunobu, Hiroyuki*; et al.

Journal of Nuclear Science and Technology, 39(11), p.1125 - 1136, 2002/11

 Times Cited Count:649 Percentile:96.97(Nuclear Science & Technology)

Evaluation for JENDL-3.3 has been performed by considering the accumulated feedback information and various benchmark tests of the previous library JENDL-3.2. The major problems of the JENDL-3.2 data were solved by the new library: overestimation of criticality values for thermal fission reactors was improved by the modifications of fission cross sections and fission neutron spectra for $$^{235}$$U; incorrect energy distributions of secondary neutrons from important heavy nuclides were replaced with statistical model calculations; the inconsistency between elemental and isotopic evaluations was removed for medium-heavy nuclides. Moreover, covariance data were provided for 20 nuclides. The reliability of JENDL-3.3 was investigated by the benchmark analyses on reactor and shielding performances. The results of the analyses indicate that JENDL-3.3 predicts various reactor and shielding characteristics better than JENDL-3.2.

JAEA Reports

Development of quick-response area-averaged void fraction meter; Application to BWR condition

Iguchi, Tadashi; Watanabe, Hironori; Kimura, Mamoru*; Anoda, Yoshinari

JAERI-Research 2001-032, 111 Pages, 2001/05

JAERI-Research-2001-032.pdf:4.14MB

no abstracts in English

JAEA Reports

Data report of BWR post-CHF tests; Transient core thermal-hydraulic program (Contract research)

Iguchi, Tadashi; Ito, Hideo; Kiuchi, Toshio; Watanabe, Hironori; Kimura, Mamoru*; Anoda, Yoshinari

JAERI-Data/Code 2001-013, 502 Pages, 2001/03

JAERI-Data-Code-2001-013.pdf:32.38MB

no abstracts in English

JAEA Reports

Development of quick-responce area-averaged void fraction meter

Watanabe, Hironori; Iguchi, Tadashi; Kimura, Mamoru; Anoda, Yoshinari

JAERI-Research 2000-043, 77 Pages, 2000/11

JAERI-Research-2000-043.pdf:6.55MB

no abstracts in English

Journal Articles

Structural study of lithium titanogallate prepared by ion exchange via one-dimensional tunnel-like pathways

*; *; *; Watanabe, Mamoru*; *; Morii, Yukio; Shimojo, Yutaka

Solid State Ionics, 113-115, p.471 - 475, 1998/00

 Times Cited Count:3 Percentile:22.5(Chemistry, Physical)

no abstracts in English

Journal Articles

Development of high power negative ion sources and accelerators for neutral beam heating and current drive systems

Inoue, Takashi; Hanada, Masaya; Kuriyama, Masaaki; *; Matsuoka, Mamoru; Miyamoto, Kenji; Ohara, Yoshihiro; Okumura, Yoshikazu; Watanabe, Kazuhiro

IAEA-CN-60/F-10, 0, p.687 - 693, 1995/00

no abstracts in English

Journal Articles

Surge suppression in a power supply of a neutral beam injector

Watanabe, Kazuhiro; Ito, Takao*; Matsuoka, Mamoru

Purazuma, Kaku Yugo Gakkai-Shi, 69(10), p.1229 - 1241, 1993/10

no abstracts in English

Journal Articles

Development of acceleration power supplies of a neutral beam injection system using GTO switches with transient-voltage regulation capability

Matsuoka, Mamoru; *; Matsuda, Shinzaburo; *; Mizuno, Makoto; *; Watanabe, Kazuhiro; *

Denki Gakkai Rombunshi, B, 112(11), p.1035 - 1044, 1992/00

no abstracts in English

JAEA Reports

A Review of JAERI R&D activities on the negative-ion-based neutral beam injection system

Ohara, Yoshihiro; Akiba, Masato; Araki, Masanori; Dairaku, Masayuki; Hanada, Masaya; Inoue, Takashi; Kojima, Hiroaki; Kuriyama, Masaaki; *; Matsuoka, Mamoru; et al.

JAERI-M 90-154, 119 Pages, 1990/09

JAERI-M-90-154.pdf:3.06MB

no abstracts in English

JAEA Reports

Radiation monitoring of JRR-2 during its experiment and power-up test

Fukuda, Seiji; Kato, Jinzo; Onishi, Takeshi; Watanabe, Kozo; Okubo, Katsuichi; Ouchi, Masafusa; Isozaki, Hiroshi; Seki, Mamoru; Mito, Norio; Tsuruo, Akira; et al.

JAERI 1028, 55 Pages, 1962/10

JAERI-1028.pdf:4.9MB

no abstracts in English

Oral presentation

Vacancy-type defects in garnet crystals revealed by gamma-ray-induced positron annihilation spectroscopy

Kitaura, Mamoru*; Fujimori, Kosuke*; Taira, Yoshitaka*; Fujimoto, Masaki*; Zen, H.*; Hirade, Tetsuya; Kamada, Kei*; Watanabe, Shinta*; Onishi, Akimasa*

no journal, , 

Positron annihilation spectroscopy is the only way to investigate the properties of cation vacancies because they are negatively charged. We generated high-energy pulsed gamma rays by the vertical collision of an ultrashort pulse laser and electron beam. In this study, we investigated the vacancy-type defects present in the crystals of GAGG(Gd$$_{3}$$Al$$_{2}$$Ga$$_{3}$$O$$_{12}$$), GAGG: Ce and GAGG: Ce, Mg by positron annihilation lifetime spectroscopy using the high-energy gamma rays. The lifetime of the defect-related component was significantly changed by Mg co-doping. This was understood by considering aggregates of Mg$$^{2+}$$ ions at Al/Ga sites with oxygen vacancies, which resulted in the formation of vacancy clusters.

Oral presentation

Origin of phosphorescence in Ce:Gd$$_{3}$$Al$$_{2}$$Ga$$_{3}$$O$$_{12}$$ crystals revealed by gamma-ray induced positron annihilation lifetime spectroscopy

Fujimori, Kosuke*; Kitaura, Mamoru*; Taira, Yoshitaka*; Fujimoto, Masaki*; Zen, H.*; Hirade, Tetsuya; Kamada, Kei*; Watanabe, Shinta*; Onishi, Akimasa*

no journal, , 

We generated high-energy pulsed gamma rays by the vertical collision of an ultrashort pulse laser and electron beam. In this study, we investigated the vacancy-type defects present in the crystals of GAGG(Gd$$_{3}$$Al$$_{2}$$Ga$$_{3}$$O$$_{12}$$), GAGG: Ce and GAGG: Ce, Mg by positron annihilation lifetime spectroscopy using the high-energy gamma rays. The lifetime of the defect-related component was significantly changed by Mg co-doping. This indicates that the Al/Ga vacancies disappear. This fact corresponds well with the suppression of the phosphorescence component and is an important result showing that the Mg co-doping is effective in suppressing the shallow electron capture center.

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