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Kosuge, Atsushi; Ando, Kota*; Yamamoto, Keisuke*; Nakajima, Takashi*
Optics & Laser Technology, 201, p.115269_1 - 115269_6, 2026/09
Times Cited Count：0 Percentile：0.00(Optics)Valet, T.*; Yamamoto, Kei; Pigeau, B.*; de Loubens, G.*; Klein, O.*
Physical Review B, 113(10), p.L100410_1 - L100410_6, 2026/03
Times Cited Count：0 Percentile：0.00(Materials Science, Multidisciplinary)Valet, T.*; Yamamoto, Kei; Pigeau, B.*; de Loubens, G.*; Klein, O.*
Physical Review B, 113(10), p.104437_1 - 104437_17, 2026/03
Times Cited Count：0 Percentile：0.00(Materials Science, Multidisciplinary)Tamura, Fumihiko; Okita, Hidefumi; Yamamoto, Masanobu; Yoshii, Masahito*; Omori, Chihiro*; Seiya, Kiyomi*; Sugiyama, Yasuyuki*; Nomura, Masahiro; Shimada, Taihei; Hasegawa, Katsushi*; et al.
Proceedings of 22nd Annual Meeting of Particle Accelerator Society of Japan (Internet), p.269 - 273, 2026/03
The replacement project for the Magnetic Alloy (MA) cavities of the 3GeV RCS at J-PARC has been underway for several years. The original cavities are the push-pull (PP) configuration, where rf current is supplied alternately from a pair of tetrode tubes to the electrodes on the upstream and downstream sides of the acceleration gap. All cavities are to be replaced with newly developed single-ended (SE) cavities. In PP cavities, significant unbalance in the operation of the upstream and downstream tetrodes due to multiharmonic rf occurs. This unbalance has been one of the limiting factor of beam intensity. This unbalance does not occur essentially in SE cavities. Currently, six of the twelve cavities have been replaced. The SE cavity does not have a configuration to cancel even-order higher harmonics, therefore the harmonic components are different from those of the original PP cavity. We report on the operational experience with the single-ended cavity at the J-PARC RCS.
Chen, J.*; Yamamoto, Kei; 13 of others*
Physical Review Letters, 136(5), p.056702_1 - 056702_8, 2026/02
Times Cited Count：0 Percentile：0.00(Physics, Multidisciplinary)Kurebayashi, Hidekazu*; Yamamoto, Kei; Seki, Takeshi*; 9 of others*
Nature Materials, 10 Pages, 2026/00
Times Cited Count：0 Percentile：0.00(Chemistry, Physical)Marium, M.*; Aoki, Kentaro*; He, Y.*; Yamamoto, Katsuhiro*; Suwansoontorn, A.*; Ikuta, Seiya*; Hara, Mitsuo*; Nagano, Shusaku*; Nagao, Yuki*; Nishikawa, Kei*; et al.
ACS Applied Energy Materials (Internet), 8(22), p.16589 - 16600, 2025/11
Times Cited Count：0 Percentile：0.00(Chemistry, Physical)K
nstle, K.*; Yamamoto, Kei; 7 of others*
Nature Communications (Internet), 16, p.10116_1 - 10116_8, 2025/11
Times Cited Count：4 Percentile：44.91(Multidisciplinary Sciences)Taguchi, Miki*; Miyata, Noboru*; Miyazaki, Tsukasa*; Aoki, Hiroyuki; Ozawa, Satoru*; Hasegawa, Ryuichi*; Morimitsu, Yuma*; Kawaguchi, Daisuke*; Yamamoto, Satoru*; Tanaka, Keiji*
Polymer Journal, 57(7), p.737 - 743, 2025/07
Times Cited Count：0 Percentile：0.00(Polymer Science)Sud, A.*; Yamamoto, Kei; Iihama, Satoshi*; Ishibashi, Kazuaki*; Fukami, Shunsuke*; Kurebayashi, Hidekazu*; Mizukami, Shigemi*
Physical Review Letters, 134(24), p.246704_1 - 246704_7, 2025/06
Times Cited Count：9 Percentile：90.81(Physics, Multidisciplinary)Sheng, L.*; Yamamoto, Kei; 18 of others*
Nature Physics, 21(5), p.740 - 745, 2025/05
Times Cited Count：17 Percentile：98.03(Physics, Multidisciplinary)
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Ba, Y.*; Yamamoto, Kei; 6 of others*
Physical Review B, 111(10), p.104401_1 - 104401_15, 2025/03
Times Cited Count：7 Percentile：87.62(Materials Science, Multidisciplinary)Yamamoto, Keisuke; Nakagawa, Takuya; Shimojo, Hiroto; Kijima, Jun; Miura, Daiya; Onose, Yoshihiko*; Namba, Koji*; Uchida, Hiroaki*; Sakamoto, Kazuhiko*; Ono, Chika*; et al.
JAEA-Technology 2024-019, 211 Pages, 2025/02
JAEA-Technology-2024-019.pdf:35.35MB
The uranium enrichment facilities at the Nuclear Fuel Cycle Engineering Laboratories of Japan Atomic Energy Agency (JAEA) were constructed sequentially to develop uranium enrichment technology with centrifugal separation method. The developed technologies were transferred to Japan Nuclear Fuel Limited until 2001. And the original purpose has been achieved. Wastewater Treatment Facility, one of the uranium enrichment facilities, was constructed in 1976 to treat radioactive liquid waste generated at the facilities, and it finished the role in 2008. In accordance with the Medium/Long-Term Management Plan of JAEA Facilities, interior equipment installed in this facility had been dismantled and removed since November 2021 to August 2023. This report summarizes the findings obtained through the work related to the contamination inspection methods cancellation the controlled area of Wastewater Treatment Facility from September 2023 to March 2024.
Nii, Yoichi*; Yamamoto, Kei; Kanno, Masaki*; Maekawa, Sadamichi*; Onose, Yoshinori*
Physical Review Letters, 134(2), p.027001_1 - 027001_5, 2025/01
Times Cited Count：7 Percentile：90.81(Physics, Multidisciplinary)
C and 500CTakagi, Honoka*; Yabutsuka, Takeshi*; Hayashida, Hirotoshi*; Song, F.; Kai, Tetsuya; Shinohara, Takenao; Kurita, Keisuke; Iikura, Hiroshi; Yamamoto, Norio*; Nakajima, Minoru*; et al.
Solid State Ionics, 417, p.116716_1 - 116716_7, 2024/12
Times Cited Count：3 Percentile：28.45(Chemistry, Physical)Miyazaki, Tsukasa*; Miyata, Noboru*; Arima-Osonoi, Hiroshi*; Shimokita, Keisuke*; Yamamoto, Katsuhiro*; Takenaka, Mikihito*; Nakanishi, Yohei*; Shibata, Motoki*; Aoki, Hiroyuki; Yamada, Norifumi*; et al.
Colloids and Surfaces A; Physicochemical and Engineering Aspects, 701, p.134928_1 - 134928_8, 2024/11
Times Cited Count：1 Percentile：5.67(Chemistry, Physical)Yamamoto, Kei
Nihon Juki Gakkai Kenkyukai Shiryo, 250, p.7 - 11, 2024/10
no abstracts in English
revealed by inelastic X-ray and neutron scatteringKimura, Koji*; Tsutsui, Satoshi*; Yamamoto, Yuta*; Nakano, Akitoshi*; Kawamura, Keisuke*; Kajimoto, Ryoichi; Kamazawa, Kazuya*; Martin, A.*; Webber, K. G.*; Kakimoto, Kenichi*; et al.
Physical Review B, 110(13), p.134314_1 - 134314_10, 2024/10
Times Cited Count：3 Percentile：35.67(Materials Science, Multidisciplinary)Okita, Hidefumi; Tamura, Fumihiko; Yamamoto, Masanobu; Miyakoshi, Ryosuke*; Nomura, Masahiro; Shimada, Taihei; Yoshii, Masahito*; Omori, Chihiro*; Seiya, Kiyomi*; Hara, Keigo*; et al.
Proceedings of 21st Annual Meeting of Particle Accelerator Society of Japan (Internet), p.765 - 769, 2024/10
no abstracts in English
Tamura, Fumihiko; Sugiyama, Yasuyuki*; Okita, Hidefumi; Yamamoto, Masanobu; Yoshii, Masahito*; Omori, Chihiro*; Seiya, Kiyomi*; Nomura, Masahiro; Shimada, Taihei; Hasegawa, Katsushi*; et al.
Proceedings of 21st Annual Meeting of Particle Accelerator Society of Japan (Internet), p.774 - 776, 2024/10
The 3GeV RCS of J-PARC accelerates proton beams with a maximum beam intensity of 8e13 ppp, utilizing the features of magnetic alloy (MA) cavities. The beam is extracted in a single turn by kicker magnets, and immediately after the beam is extracted, a short voltage jump occurs in the cavity. This is due to a delay in the voltage control feedback, which takes a certain amount of time to respond to the step-like decrease of beam current upon single-turn extraction. In a wideband (Q=2) MA cavity, this response delay is observed as a voltage jump. This voltage jump can cause damage to the cavity system if the voltage at the time of extraction is high. Therefore, we prepared a logic to suppress the output synchronously with the beam extraction as a function of the LLRF control system. The details of the function and test results are reported.
