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Sugimoto, Takanori*; Toyama, Takami
Communications Physics (Internet), 6, p.291_1 - 291_6, 2023/10
Times Cited Count:2 Percentile:23.32(Physics, Multidisciplinary)Ghadimi, R.*; Hori, Masahiro*; Sugimoto, Takanori*; Toyama, Takami
Physical Review B, 108(12), p.125104_1 - 125104_18, 2023/09
Times Cited Count:5 Percentile:58.52(Materials Science, Multidisciplinary)Ghadimi, R.*; Sugimoto, Takanori*; Toyama, Takami
Physical Review B, 106(20), p.L201113_1 - L201113_6, 2022/11
Times Cited Count:5 Percentile:42.27(Materials Science, Multidisciplinary)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:7 Percentile:74.40(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.
Takamizawa, Hisashi; Hata, Kuniki; Nishiyama, Yutaka; Toyama, Takeshi*; Nagai, Yasuyoshi*
Journal of Nuclear Materials, 556, p.153203_1 - 153203_10, 2021/12
Times Cited Count:4 Percentile:40.86(Materials Science, Multidisciplinary)Solute clusters (SCs) formed in pressurized water reactor surveillance test specimens neutron-irradiated to a fluence of 1 10
n/cm
were analyzed via atom probe tomography to understand the effect of silicon on solute clustering and irradiation embrittlement of reactor pressure vessel steels. In high-Cu bearing materials, Cu atoms were aggregated at the center of cluster surrounded by the Ni, Mn, and Si atoms like a core-shell structure. In low-Cu bearing materials, Ni, Mn, and Si atoms formed cluster and these solutes were not comprised core-shell structure in SCs. While the number of Cu atoms in clusters was decreased with decreasing nominal Cu content, the number of Si atoms had clearly increased. The cluster radius (
) and number density (
) decreased and increased, respectively, with increasing nominal Si content. The shift in the reference temperature for nil-ductility transition (
RT
) showed a good correlation with the square root of volume fraction (
) multiplied by r (
). This suggested that the dislocation cutting through the particles mechanism dominates the precipitation hardening responsible for irradiation embrittlement. The negative relation between the nominal Si content and
RT
indicated that increasing of nominal Si content reduces the degree of embrittlement.
Ghadimi, R.*; Sugimoto, Takanori*; Tanaka, Kaori*; Toyama, Takami
Physical Review B, 104(14), p.144511_1 - 144511_10, 2021/10
Times Cited Count:30 Percentile:87.03(Materials Science, Multidisciplinary)Wada, Kazuhiro*; Sugimoto, Takanori*; Toyama, Takami
Physical Review B, 104(7), p.075119_1 - 075119_12, 2021/08
Times Cited Count:7 Percentile:42.22(Materials Science, Multidisciplinary)Ghadimi, R.*; Sugimoto, Takanori*; Toyama, Takami
Physical Review B, 102(22), p.224201_1 - 224201_9, 2020/12
Times Cited Count:14 Percentile:59.14(Materials Science, Multidisciplinary)Suzudo, Tomoaki; Takamizawa, Hisashi; Nishiyama, Yutaka; Caro, A.*; Toyama, Takeshi*; Nagai, Yasuyoshi*
Journal of Nuclear Materials, 540, p.152306_1 - 152306_10, 2020/11
Times Cited Count:12 Percentile:75.34(Materials Science, Multidisciplinary)Spinodal decomposition in thermally aged Fe-Cr alloys leads to significant hardening, which is the direct cause of the so-called 475C-embrittlement. To illustrate how spinodal decomposition induces hardening by atomistic interactions, we conducted a series of numerical simulations as well as reference experiments. The numerical results indicated that the hardness scales linearly with the short-range order (SRO) parameter, while the experimental result reproduced this relationship within statistical error. Both seemingly suggest that neighboring Cr-Cr atomic pairs essentially cause hardening, because SRO is by definition uniquely dependent on the appearance probability of such pairs. A further numerical investigation supported this notion, as it suggests that the dominant cause of hardening is the pinning effect of dislocations passing over such Cr-Cr pairs.
Fujihara, Masayoshi*; Morita, Katsuhiro*; Mole, R.*; Mitsuda, Setsuo*; Toyama, Takami*; Yano, Shinichiro*; Yu, D.*; Sota, Shigetoshi*; Kuwai, Tomohiko*; Koda, Akihiro*; et al.
Nature Communications (Internet), 11, p.3429_1 - 3429_7, 2020/07
Times Cited Count:51 Percentile:92.31(Multidisciplinary Sciences)Toyama, Takami; Mori, Michiyasu; Sota, Shigetoshi*
Physical Review B, 97(23), p.235137_1 - 235137_7, 2018/06
Times Cited Count:12 Percentile:46.67(Materials Science, Multidisciplinary)Sugimoto, Takanori*; Mori, Michiyasu; Toyama, Takami; Maekawa, Sadamichi
Physical Review B, 97(14), p.144424_1 - 144424_10, 2018/04
Times Cited Count:6 Percentile:26.66(Materials Science, Multidisciplinary)Ishii, Kenji*; Toyama, Takami*; Asano, Shun*; Sato, Kentaro*; Fujita, Masaki*; Wakimoto, Shuichi; Tsutsui, Kenji*; Sota, Shigetoshi*; Miyawaki, Jun*; Niwa, Hideharu*; et al.
Physical Review B, 96(11), p.115148_1 - 115148_8, 2017/09
Times Cited Count:33 Percentile:77.62(Materials Science, Multidisciplinary)Takamizawa, Hisashi; Shimizu, Yasuo*; Inoue, Koji*; Nozawa, Yasuko*; Toyama, Takeshi*; Yano, Fumiko*; Inoue, Masao*; Nishida, Akio*; Nagai, Yasuyoshi*
Applied Physics Express, 9(10), p.106601_1 - 106601_4, 2016/10
Times Cited Count:3 Percentile:13.48(Physics, Applied)Sugimoto, Takanori*; Mori, Michiyasu; Toyama, Takami*; Maekawa, Sadamichi
Physics Procedia, 75, p.861 - 867, 2015/12
Times Cited Count:0 Percentile:0.00(Physics, Applied)Tsutsui, Kenji; Kaneshita, Eiji*; Toyama, Takami*
Physical Review B, 92(19), p.195103_1 - 195103_5, 2015/11
Times Cited Count:2 Percentile:9.02(Materials Science, Multidisciplinary)Nonresonant inelastic X-ray scattering (NIXS) is a possible tool to detect charge excitations in electron systems. In addition, multipole transitions at high-momentum-transfer region open a new possibility to determine orbital-selective electronic excitations in multi-orbital itinerant 3 electron systems. As a theoretical example, we chose the antiferromagnetic state of iron arsenides and demonstrate that the orbital-selective excitations are detectable by choosing appropriate momentum transfer in NIXS. We propose that both NIXS and resonant inelastic X-ray scattering are complementary to each other for fully understanding the nature of orbital excitations in multi-orbital itinerant electron systems.
Sugimoto, Takanori*; Mori, Michiyasu; Toyama, Takami*; Maekawa, Sadamichi
JPS Conference Proceedings (Internet), 8, p.034005_1 - 034005_6, 2015/09
Sugimoto, Takanori*; Mori, Michiyasu; Toyama, Takami*; Maekawa, Sadamichi
Physical Review B, 92(12), p.125114_1 - 125114_6, 2015/09
Times Cited Count:11 Percentile:42.43(Materials Science, Multidisciplinary)Toyama, Takami*; Tsutsui, Kenji; Mori, Michiyasu; Sota, Shigetoshi*; Yunoki, Seiji*
Physical Review B, 92(1), p.014515_1 - 014515_8, 2015/07
Times Cited Count:14 Percentile:49.75(Materials Science, Multidisciplinary)Resonant inelastic X-ray scattering (RIXS) tuned for Cu edge is a possible tool to detect charge excitations in cuprate superconductors. We theoretically investigate the possibility for observing a collective charge excitation by the RIXS. The RIXS process via the intermediate state inevitably makes the spectral weight of charge excitation stronger in electron doping than in hole doping. Electron-hole asymmetry also appears in dynamical charge structure factor, showing a new enhanced small-momentum low-energy mode in electron doping. These facts indicate a possibility of detecting the new charge mode by RIXS in electron-doped systems.
Sugimoto, Takanori*; Mori, Michiyasu; Toyama, Takami*; Maekawa, Sadamichi
JPS Conference Proceedings (Internet), 3, p.014016_1 - 014016_5, 2014/06