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catalyst condition at J-PARC cryogenic moderator systemAriyoshi, Gen; Tatsumoto, Hideki*; Teshigawara, Makoto; Hasegawa, Takumi*; Shiro, Yuki*; Horikawa, Yuka*
IOP Conference Series; Materials Science and Engineering, 1327(1), p.012155_1 - 012155_6, 2025/05
Times Cited Count：0 Percentile：0.00(Thermodynamics)The Spallation Neutron Source (SNS) at the Oak Ridge National Laboratory in the United States of America, which operates at 1.4 MW of high-power proton beam, has recently measured "back conversion production" in which parahydrogen, a nuclear spin isomer, is converted to orthohydrogen in an intense neutron field in a liquid hydrogen circulation system not installing any catalyst, for the first time in the world. The amount of para-to-orthohydrogen back conversion was 0.374 [m/MW/day]. Comparing parahydrogen and orthohydrogen, the total neutron cross section differs more than two orders of magnitude, so the increase in orthohydrogen has a significant impact on the generated neutron performance. Therefore, in the J-PARC hydrogen circulation system, a catalyst is introduced to maintain the parahydrogen state. However, at present, methods have not been developed yet to directly diagnose catalyst performance and/or degradation in-situ. In this study, we devised a new method to easily and intentionally change the amount of orthohydrogen in the J-PARC hydrogen circulation system, and attempted to evaluate catalyst kinetics by intentionally introducing an increase in orthohydrogen equivalent to back conversion into the circulation system. This method has the potential to contribute to the in-situ diagnostic catalyst characterization and to the calculation of neutron performance that depends on the ortho-to-parahydrogen ratio.
Arai, Yoichi; Watanabe, So; Nakahara, Masaumi; Funakoshi, Tomomasa; Hoshino, Takanori; Takahatake, Yoko; Sakamoto, Atsushi; Aihara, Haruka; Hasegawa, Kenta; Yoshida, Toshiki; et al.
Progress in Nuclear Science and Technology (Internet), 7, p.168 - 174, 2025/03
The Japan Atomic Energy Agency (JAEA) has been conducting a project named "Systematic Treatment of RAdioactive liquid waste for Decommissioning (STRAD)" project since 2018 for fundamental and practical studies for treating radioactive liquid wastes with complicated compositions. Fundamental studies have been conducted using genuine liquid wastes accumulated in a hot laboratory of the JAEA called the Chemical Processing Facility (CPF), and treatment procedures for all liquid wastes in CPF were successfully designed on the results obtained. As the next phase of the project, new fundamental and practical studies on primarily organic liquid wastes accumulated in different facilities of JAEA are in progress. This paper reviews the representative achievements of the STRAD project and introduces an overview of ongoing studies.
Teshigawara, Makoto; Lee, Y.*; Tatsumoto, Hideki*; Hartl, M.*; Aso, Tomokazu; Iverson, E. B.*; Ariyoshi, Gen; Ikeda, Yujiro*; Hasegawa, Takumi*
Nuclear Instruments and Methods in Physics Research B, 557, p.165534_1 - 165534_10, 2024/12
Times Cited Count：1 Percentile：30.35(Instruments & Instrumentation)At Japanese Spallation Neutron Source in J-PARC, the para-hydrogen fraction was measured by using Raman spectroscopy in-situ for an integrated beam power of 9.4 MW
h at 1 MW operation, to evaluate the functionality of the ferric oxyhydroxide catalyst. This result showed that full functionality of the catalyst was retained up to the 1 MW operation. We attempted to study the effect of neutron scattering driven para to ortho-hydrogen back-conversion rate in the absence of the catalyst effect with a bypass line without catalyst. The measured increase of ortho-hydrogen fraction was 0.44% for an integrated beam power of 2.4 MWh at 500 kW operation, however, which was considered to be due to not only to neutron collisions in cold moderators but also to the high ortho-hydrogen fraction of initially static liquid hydrogen in the bypass line and passive exudation of quasi-static hydrogen in the catalyst vessel to the main loop.
Miyagawa, Akihisa*; Hayashi, Naoki*; Kuzure, Yoshiaki*; Takahashi, Takumi*; Iwamoto, Hibiki*; Arai, Tsuyoshi*; Nagatomo, Shigenori*; Miyazaki, Yasunori; Hasegawa, Kenta; Sano, Yuichi; et al.
Bulletin of the Chemical Society of Japan, 96(7), p.671 - 676, 2023/07
Times Cited Count：8 Percentile：53.09(Chemistry, Multidisciplinary)We investigated the distribution mechanism of Eu(III) in a single polymer-coated silica particle including nitrilotriacetamide (NTA) extractants known as HONTA and TOD2EHNTA. The present study provides a valuable approach for the evaluation and enhancement of the functionality of "single extractant-impregnated polymer-coated silica particle".
-based superconductor LaBiSO
FTamatsukuri, Hiromu; Hasegawa, Takumi*; Sagayama, Hajime*; Mizumaki, Masaichiro*; Murakami, Yoichi*; Kajitani, Joe*; Higashinaka, Ryuji*; Matsuda, Tatsuma*; Aoki, Yuji*; Tsutsui, Satoshi*
Physical Review B, 107(2), p.024303_1 - 024303_8, 2023/01
Times Cited Count：2 Percentile：16.78(Materials Science, Multidisciplinary)Suekuni, Koichiro*; Lee, C. H.*; Tanaka, Hiromi*; Nishibori, Eiji*; Nakamura, Atsushi*; Kasai, Hidetaka*; Mori, Hitoshi*; Usui, Hidetomo*; Ochi, Masayuki*; Hasegawa, Takumi*; et al.
Advanced Materials, 30(13), p.1706230_1 - 1706230_6, 2018/03
Times Cited Count：68 Percentile：89.61(Chemistry, Multidisciplinary)Thermoelectric materials for highly efficient devices must satisfy conflicting requirements of high electrical conductivity and low thermal conductivity. In this paper, we studied the crystal structure and phonon dynamics of tetrahedrites (Cu,Zn)
(Sb,As)
S
. The results revealed that the Cu atoms in a planar coordination are rattling, which effectively scatter phonons. These findings provide a new strategy for the development of highly efficient thermoelectric materials with planar coordination.
Se
Lee, C. H.*; Nishida, Atsuhiro*; Hasegawa, Takumi*; Nishiate, Hirotaka*; Kunioka, Haruno*; Kawamura, Seiko; Nakamura, Mitsutaka; Nakajima, Kenji; Mizuguchi, Yoshikazu*
Applied Physics Letters, 112(2), p.023903_1 - 023903_4, 2018/01
Times Cited Count：34 Percentile：76.48(Physics, Applied)Low energy phonons in LaOBiSSe are studied using inelastic neutron scattering. Dispersionless flat phonon branches that are mainly associated with a large vibration of Bi atoms are observed at a relatively low energy of 
= 6 - 6.7 meV. The phonon energy softens upon Se doping owing to its heavier atomic mass than S atom and the expansion of lattice constant. Simultaneously, the lattice thermal conductivity lowered upon Se doping as the same manner of the phonon softening. These suggest that despite the lack of an oversized cage in LaOBiSSe, rattling motions of Bi atoms can scatter phonon like rattling in cage compounds, contributing to enhance the thermoelectric property.
Kawashima, Hisato; Hasegawa, Mitsuru*; Fuchs, G.*; Matoba, Toru; ; Hoshino, Katsumichi; Kawakami, Tomohide; Yamamoto, Takumi
Japanese Journal of Applied Physics, 33(6A), p.3590 - 3596, 1994/00
Times Cited Count：4 Percentile：29.70(Physics, Applied)no abstracts in English
Kawashima, Hisato; Hasegawa, Mitsuru*; Matoba, Toru; Uesugi, Yoshihiko; Hoshino, Katsumichi; Kawakami, Tomohide; Yamamoto, Takumi
JAERI-M 87-157, 20 Pages, 1987/10
no abstracts in English
Mori, Masahiro; Miura, Yukitoshi; Suzuki, Norio; Uesugi, Yoshihiko; Tamai, Hiroshi; Ogawa, Toshihide; Ogawa, Hiroaki; Otsuka, Hideo; Odajima, Kazuo; Kasai, Satoshi; et al.
JAERI-M 87-117, 13 Pages, 1987/08
no abstracts in English
Sengoku, Seio; ; Hasegawa, Mitsuru; Hoshino, Katsumichi; Kasai, Satoshi; Kawakami, Tomohide; Kawashima, Hisato; Matoba, Toru; Matsuda, Toshiaki; Matsumoto, Hiroshi; et al.
Physical Review Letters, 59(4), p.450 - 453, 1987/00
Times Cited Count：49 Percentile：87.55(Physics, Multidisciplinary)no abstracts in English
