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Kondo, Yasuhiro; Chimura, Motoki; Cicek, E.*; Fukui, Yuji*; Futatsukawa, Kenta*; Fuwa, Yasuhiro; Goto, Rikuto*; Hirano, Koichiro; Ishikawa, Masaki*; Ito, Takashi; et al.
Proceedings of 22nd Annual Meeting of Particle Accelerator Society of Japan (Internet), p.124 - 129, 2026/03
Various upgrade plans of the J-PARC linac are underway, and repetition-rate doubling project is one of the most important part. Currently, the linac supplies a 400~MeV H
ion beam to the 3~GeV synchrotron (RCS) at a repetition rate of 25~Hz. However, to deliver the beam to both RCS and proton-beam irradiation facility under planning, it is necessary to raise the repetition rate from 25~Hz to 50~Hz. Prior to construction of the beamline to the irradiation facility, we conducted a verification of the 50~Hz operation of all the linac apparatus simultaneously within the current operational limits in May 2025. And also, the verification of the 50~Hz operation of the particle counter system, which is one of the most important safety device of the J-PARC accelerator, was conducted. As a result, any significant problems were not found out, and it is now ready for the upcoming 50~Hz-beam acceleration demonstration. This paper describes this details of the demonstration of the 50~Hz operation, without beam acceleration, of the J-PARC linac.
Chimura, Motoki; Watanabe, Kazuhiko*; Takahashi, Hiroki; Hirano, Koichiro; Shinto, Katsuhiro; Kitamura, Ryo; Kawase, Masato*; Suzuki, Takahiro*; Morishita, Takatoshi
Proceedings of 22nd Annual Meeting of Particle Accelerator Society of Japan (Internet), p.709 - 713, 2026/03
no abstracts in English
Saha, P. K.; Harada, Hiroyuki; Tamura, Fumihiko; Shobuda, Yoshihiro; Kojima, Kunihiro; Yoshimoto, Masahiro; Okita, Hidefumi; Okabe, Kota; Hatakeyama, Shuichiro; Nakanoya, Takamitsu; et al.
Proceedings of 22nd Annual Meeting of Particle Accelerator Society of Japan (Internet), p.549 - 553, 2026/03
Ueno, Katsuhiro; Ouchi, Kazuki; Watanabe, Masayuki
Results in Engineering (Internet), 29, p.109246_1 - 109246_10, 2026/03
Shibata, Motoki*; Takenaka, Mikihito*; Motokawa, Ryuhei; Kumada, Takayuki; Ueda, Yuki; Miyazaki, Tsukasa*; Nakanishi, Yohei*; Abe, Jun*; Iwase, Hiroki*; Shibayama, Mitsuhiro*; et al.
Polymer, 340, p.129203_1 - 129203_7, 2025/12
Times Cited Count：0 Percentile：0.00(Polymer Science)Okabe, Kota; Kamiya, Junichiro; Moriya, Katsuhiro; Shobuda, Yoshihiro; Takahashi, Hiroki; Takayanagi, Tomohiro; Yoshimoto, Masahiro; Yamamoto, Masanobu; Yamamoto, Kazami
Nuclear Instruments and Methods in Physics Research A, 1080, p.170601_1 - 170601_9, 2025/11
Times Cited Count：0 Percentile：0.00(Instruments & Instrumentation)Liu, Y.*; Otani, Masashi*; Miyao, Tomoaki*; Nakazawa, Yuga*; Shibata, Takanori*; Nammo, Kesao*; Fang, Z.*; Futatsukawa, Kenta*; Fukui, Yuji*; Mizobata, Satoshi*; et al.
Proceedings of 16th International Particle Accelerator Conference (IPAC25) (Internet), p.855 - 857, 2025/11
Okabe, Kota; Shibata, Takanori*; Moriya, Katsuhiro; Okoshi, Kiyonori; Miyao, Tomoaki*; Otani, Masashi*; Liu, Y.*; Morishita, Takatoshi
Proceedings of 16th International Particle Accelerator Conference (IPAC25) (Internet), p.1527 - 1529, 2025/11
-butadiene) reinforced by carbon blackWatanabe, Yuki*; Kumagawa, Daiki*; Karitani, Shu*; Inoue, Tadashi*; Iwabuki, Hitoshi*; Nakanishi, Yohei*; Shibata, Motoki*; Motokawa, Ryuhei; Sugita, Tsuyoshi; Ueda, Yuki; et al.
Macromolecules, 58(16), p.8641 - 8648, 2025/08
Times Cited Count：0 Percentile：0.00(Polymer Science)Ouchi, Kazuki; Ueno, Katsuhiro; Watanabe, Masayuki
Scientific Reports (Internet), 15, p.18515_1 - 18515_7, 2025/05
Times Cited Count：1 Percentile：29.60(Multidisciplinary Sciences)We first demonstrate a nonaqueous rechargeable battery using uranium and iron as active materials. This uranium-iron battery achieves an open-circuit voltage of approximately 1.3 V, exhibits stable cycling performance, and delivers a good Coulombic efficiency of 86
2%. These characteristics suggest a promising avenue for utilizing depleted uranium in innovative applications.
Ueno, Katsuhiro; Ouchi, Kazuki; Watanabe, Masayuki
Hosha Kagaku, (51), p.11 - 14, 2025/03
no abstracts in English
Saha, P. K.; Harada, Hiroyuki; Shobuda, Yoshihiro; Chimura, Motoki; Okabe, Kota; Nakanoya, Takamitsu; Moriya, Katsuhiro; Yamamoto, Kazami; Tamura, Fumihiko; Okita, Hidefumi; et al.
Proceedings of 15th International Particle Accelerator Conference (IPAC'24) (Internet), p.939 - 942, 2024/07
Saha, P. K.; Harada, Hiroyuki; Shobuda, Yoshihiro; Tamura, Fumihiko; Okita, Hidefumi; Okabe, Kota; Nakanoya, Takamitsu; Hatakeyama, Shuichiro; Moriya, Katsuhiro; Takayanagi, Tomohiro; et al.
Journal of Physics; Conference Series, 2687(5), p.052020_1 - 052020_7, 2024/01
Times Cited Count：1 Percentile：71.31(Physics, Atomic, Molecular & Chemical)Shibata, Motoki*; Nakanishi, Yohei*; Abe, Jun*; Arima, Hiroshi*; Iwase, Hiroki*; Shibayama, Mitsuhiro*; Motokawa, Ryuhei; Kumada, Takayuki; Takata, Shinichi; Yamamoto, Katsuhiro*; et al.
Polymer Journal, 55(11), p.1165 - 1170, 2023/11
Times Cited Count：6 Percentile：30.54(Polymer Science)
H
OFujihara, Masayoshi; Hagihara, Masato; Morita, Katsuhiro*; Murai, Naoki; Koda, Akihiro*; Okabe, Hirotaka*; Mitsuda, Setsuo*
Physical Review B, 107(5), p.054435_1 - 054435_8, 2023/02
Times Cited Count：5 Percentile：35.30(Materials Science, Multidisciplinary)The 
= 1/2 Heisenberg linear chain antiferromagnet is the simplest spin model; nevertheless it serves as a platform for various quantum many-body phenomena. Here, we report the magnetic behavior of a quasi-one-dimensional antiferromagnet KCuPOHO. A long-range commensurate antiferromagnetic order with ordered moment 0.31(1) 
per spin occurs at 
= 11.7(1) K. Above , the inelastic neutron excitation is characterized by a two spinon continuum. The intrachain interaction 
and interchain interaction 
are estimated to be 172 K and 4.25(4) K, respectively; thus the ratio of the / = 0.0247(3). At lower energies, below , a spin gap is observed in the dispersive excitations. These results are consistent with characteristics observed in weakly interacting = 1/2 Heisenberg chain system.
Okabe, Kota; Liu, Y.*; Otani, Masashi*; Moriya, Katsuhiro; Miyao, Tomoaki*; Kitamura, Ryo; Hirano, Koichiro; Oguri, Hidetomo; Kinsho, Michikazu
Proceedings of 19th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.885 - 888, 2023/01
The J-PARC linac has a medium energy beamline (MEBT1) between RFQ and DTL. The MEBT1 is equipped with an RF beam chopper system to control the macro-bunch beam shape in the longitudinal direction so as to match the Circular Accelerator (RCS) in the latter stage. Two buncher cavities are installed in the existing MEBT1 for the matching the longitudinal shape of the beam with the chopper system and the downstream DTL. However, in principle, a total of three bunchers are required: one for the chopper system and two for beam shape matching with the DTL. Therefore, there have been long discussions about the design of the new MEBT1, which is an MEBT1 with a buncher added. On the other hand, in MEBT1, the space charge effect is very strong, and it is difficult to install beam monitors in the DTL section, so it is difficult to clarify the current experimental results using numerical simulations. We first conducted systematic beam experiments to investigate how the beam quality could be improved by adding a buncher to the MEBT1. As a result of examining the risks and benefits that would improve from remaking MEBT1 from the results of beam experiments, it was found that there was little merit in installing the new MEBT1 in terms of achieving a beam power of a little over 1 MW at the J-PARC accelerators. It was determined that the MEBT1 of 1 can be adequately handled. In this paper, we report the results of beam experiments on the MEBT1 and the review process of the new MEBT1.
Saha, P. K.; Okabe, Kota; Nakanoya, Takamitsu; Yoshimoto, Masahiro; Shobuda, Yoshihiro; Harada, Hiroyuki; Tamura, Fumihiko; Okita, Hidefumi; Hatakeyama, Shuichiro; Moriya, Katsuhiro; et al.
Proceedings of 19th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1 - 5, 2023/01
Cu(PO)SO 5HO as a model antiferromagnetic spin-1/2 Heisenberg 
- chainFujihara, Masayoshi; Jeschke, H. O.*; Morita, Katsuhiro*; Kuwai, Tomohiko*; Koda, Akihiro*; Okabe, Hirotaka*; Matsuo, Akira*; Kindo, Koichi*; Mitsuda, Setsuo*
Physical Review Materials (Internet), 6(11), p.114408_1 - 114408_8, 2022/11
Times Cited Count：6 Percentile：27.44(Materials Science, Multidisciplinary)
= 1/2 Heisenberg - chain antiferromagnets have been investigated extensively due to their exotic magnetic states. Here, we report the magnetic behavior of birchite CdCu(PO)SO5HO and its effective spin model. Experimental studies by magnetic susceptibility, magnetization, heat capacity, and 
SR measurements indicate the absence of long-range order down to 0.4 K. Theoretical studies reveal that birchite is a model compound for the - antiferromagnetic chain: the intrachain interactions and are antiferromagnetic and their magnitude is about 100 times larger than the interchain interactions. The magnitude of is two to three times larger than that of , thus the spin gap is expected to be only a few percent of that of . The temperature dependence of the specific heat shows a broad peak at about 1 K (
0.036 ), which suggests the presence of a spin gap.
Yamamoto, Kazami; Kinsho, Michikazu; Hayashi, Naoki; Saha, P. K.; Tamura, Fumihiko; Yamamoto, Masanobu; Tani, Norio; Takayanagi, Tomohiro; Kamiya, Junichiro; Shobuda, Yoshihiro; et al.
Journal of Nuclear Science and Technology, 59(9), p.1174 - 1205, 2022/09
Times Cited Count：10 Percentile：72.76(Nuclear Science & Technology)In the Japan Proton Accelerator Research Complex, the purpose of the 3 GeV rapid cycling synchrotron (RCS) is to accelerate a 1 MW, high-intensity proton beam. To achieve beam operation at a repetition rate of 25 Hz at high intensities, the RCS was elaborately designed. After starting the RCS operation, we carefully verified the validity of its design and made certain improvements to establish a reliable operation at higher power as possible. Consequently, we demonstrated beam operation at a high power, namely, 1 MW. We then summarized the design, actual performance, and improvements of the RCS to achieve a 1 MW beam.
Yamamoto, Kazami; Hatakeyama, Shuichiro; Saha, P. K.; Moriya, Katsuhiro; Okabe, Kota; Yoshimoto, Masahiro; Nakanoya, Takamitsu; Fujirai, Kosuke; Yamazaki, Yoshio; Suganuma, Kazuaki
EPJ Techniques and Instrumentation (Internet), 8(1), p.9_1 - 9_9, 2021/07
The 3 GeV Rapid Cycling Synchrotron at the Japan Proton Accelerator Research Complex supplies a high-intensity proton beam for neutron experiments. Various parameters are monitored to achieve a stable operation, and it was found that the oscillations of the charge-exchange efficiency and cooling water temperature were synchronized. We evaluated the orbit fluctuations at the injection point using a beam current of the injection dump, which is proportional to the number of particles that miss the foil and fail in the charge exchange, and profile of the injection beam. The total width of the fluctuations was approximately 0.072 mm. This value is negligible from the user operation viewpoint as our existing beam position monitors cannot detect such a small signal deviation. This displacement corresponds to a 1.63
10
variation in the dipole magnetic field. Conversely, the magnetic field variation in the L3BT dipole magnet, which was estimated by the temperature change directly, is 4.0810. This result suggested that the change in the cooling water temperature is one of the major causes of the efficiency fluctuation.
