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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：6 Percentile：84.97(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.
Cs concentrations in coastal sediments off FukushimaSuzuki, Shotaro*; Amano, Yosuke*; Enomoto, Masahiro*; Matsumoto, Akira*; Morioka, Yoshiaki*; Sakuma, Kazuyuki; Tsuruta, Tadahiko; Kaeriyama, Hideki*; Miura, Hikaru*; Tsumune, Daisuke*; et al.
Science of the Total Environment, 831, p.154670_1 - 154670_15, 2022/07
Times Cited Count：2 Percentile：29.93(Environmental Sciences)Kumagai, Tomohisa*; Miura, Yasufumi*; Miura, Naoki*; Marie, S.*; Almahdi, R.*; Mano, Akihiro; Li, Y.; Katsuyama, Jinya; Wada, Yoshitaka*; Hwang, J.-H.*; et al.
Journal of Pressure Vessel Technology, 144(1), p.011509_1 - 011509_18, 2022/02
Times Cited Count：1 Percentile：20.34(Engineering, Mechanical)To predict fracture behavior for ductile materials, some ductile fracture simulation methods different from classical approaches have been investigated based on appropriate models of ductile fracture. For the future use of the methods to overcome restrictions of classical approaches, the applicability to the actual components is of concern. In this study, two benchmark problems on the fracture tests supposing actual components were provided to investigate prediction ability of simulation methods containing parameter decisions. One was the circumferentially through-wall and surface cracked pipes subjected to monotonic bending, and the other was the circumferentially through-wall cracked pipes subjected to cyclic bending. Participants predicted the ductile crack propagation behavior by their own approaches, including FEM employed GTN yielding function with void ratio criterion, are FEM employed GTN yielding function, FEM with fracture strain or energy criterion modified by stress triaxiality, XFEM with J or delta J criterion, FEM with stress triaxiality and plastic strain based ductile crack propagation using FEM, and elastic-plastic peridynamics. Both the deformation and the crack propagation behaviors for monotonic bending were well reproduced, while few participants reproduced those for cyclic bending. To reproduce pipe deformation and fracture behaviors, most of groups needed parameters which were determined toreproduce pipe deformation and fracture behaviors in benchmark problems themselves and it is still difficult to reproduce them by using parameters only from basic materials tests.
Kitazato, Kohei*; Milliken, R. E.*; Iwata, Takahiro*; Abe, Masanao*; Otake, Makiko*; Matsuura, Shuji*; Takagi, Yasuhiko*; Nakamura, Tomoki*; Hiroi, Takahiro*; Matsuoka, Moe*; et al.
Nature Astronomy (Internet), 5(3), p.246 - 250, 2021/03
Times Cited Count：43 Percentile：96.93(Astronomy & Astrophysics)Here we report observations of Ryugu's subsurface material by the Near-Infrared Spectrometer (NIRS3) on the Hayabusa2 spacecraft. Reflectance spectra of excavated material exhibit a hydroxyl (OH) absorption feature that is slightly stronger and peak-shifted compared with that observed for the surface, indicating that space weathering and/or radiative heating have caused subtle spectral changes in the uppermost surface. However, the strength and shape of the OH feature still suggests that the subsurface material experienced heating above 300 
C, similar to the surface. In contrast, thermophysical modeling indicates that radiative heating does not increase the temperature above 200 C at the estimated excavation depth of 1 m, even if the semimajor axis is reduced to 0.344 au. This supports the hypothesis that primary thermal alteration occurred due to radiogenic and/or impact heating on Ryugu's parent body.
-XRD with synchrotron radiationMotai, Satoko*; Mukai, Hiroki*; Watanuki, Tetsu; Owada, Kenji; Fukuda, Tatsuo; Machida, Akihiko; Kuramata, Chisaki*; Kikuchi, Ryosuke*; Yaita, Tsuyoshi; Kogure, Toshihiro*
Journal of Mineralogical and Petrological Sciences, 111(5), p.305 - 312, 2016/10
Times Cited Count：16 Percentile：51.74(Mineralogy)no abstracts in English
Tomizawa, Hiromitsu*; Sato, Takahiro*; Ogawa, Kanade*; Togawa, Kazuaki*; Tanaka, Takatsugu*; Hara, Toru*; Yabashi, Makina*; Tanaka, Hitoshi*; Ishikawa, Tetsuya*; Togashi, Tadashi*; et al.
High Power Laser Science and Engineering, 3, p.e14_1 - e14_10, 2015/04
Times Cited Count：6 Percentile：34.43(Optics)no abstracts in English
Sato, Takahiro*; Iwasaki, Atsushi*; Owada, Shigeki*; Yamanouchi, Kaoru*; Takahashi, Eiji*; Midorikawa, Katsumi*; Aoyama, Makoto; Yamakawa, Koichi; Togashi, Tadashi*; Fukami, Kenji*; et al.
Journal of Physics B; Atomic, Molecular and Optical Physics, 46(16), p.164006_1 - 164006_6, 2013/08
Times Cited Count：3 Percentile：19.06(Optics)By introducing 13th- (61.7 nm) and 15th-order harmonics (53.4 nm) of femtosecond laser pulses at 800 nm into an undulator of SCSS (SPring-8 Compact SASE Source) test accelerator at RIKEN, these harmonic pulses were amplified by a factor of more than 10
with a high contrast ratio through the interaction between accelerated electron bunches and the harmonic pulses. From numerical simulations of the amplification processes of high-order harmonic pulses in the undulator, optimum conditions of the electron bunch duration interacting with the high-order harmonic pulses were investigated for generating full-coherent and intense pulses in the extreme ultraviolet wavelength region.
Togashi, Tadashi*; Takahashi, Eiji*; Midorikawa, Katsumi*; Aoyama, Makoto; Yamakawa, Koichi; Sato, Takahiro*; Iwasaki, Atsushi*; Owada, Shigeki*; Okino, Tomoya*; Yamanouchi, Kaoru*; et al.
Optics Express (Internet), 19(1), p.317 - 324, 2011/01
Times Cited Count：96 Percentile：96.45(Optics)The 13th harmonic of a Ti:sapphire (Ti:S) laser in the plateau region was injected as a seeding source to a 250-MeV free-electron-laser (FEL) amplifier. When the amplification conditions were fulfilled, strong enhancement of the radiation intensity by a factor of 650 was observed. The random and uncontrollable spikes, which appeared in the spectra of the Self-Amplified Spontaneous Emission (SASE) based FEL radiation without the seeding source, were found to be suppressed drastically to form to a narrow-band, single peak profile at 61.2 nm. The properties of the seeded FEL radiation were well reproduced by numerical simulations. We discuss the future precept of the seeded FEL scheme to the shorter wavelength region.
Takemura, Kenichi*; Watanuki, Tetsu; Owada, Kenji; Machida, Akihiko; Omura, Ayako*; Aoki, Katsutoshi
Journal of Physics; Conference Series, 215, p.012017_1 - 012017_4, 2010/03
Times Cited Count：17 Percentile：97.27(Instruments & Instrumentation)Powder X-ray diffraction experiments have been done on Ne up to 237 GPa at room temperature. Ne remains in the fcc phase up to the highest pressure. In order to observe the weak 200 reflection at ultrahigh pressure we have used the tube-cross slit at the exit side of X-rays, which effectively reduced the scattered X-rays by the diamond anvil. The lattice parameters obtained from the 111 and 200 reflections significantly differ each other, implying the existence of sizable uniaxial stress in Ne at ultrahigh pressure.
Aso, Naofumi*; Owada, Kenji; Watanuki, Tetsu; Machida, Akihiko; Omura, Ayako; Inami, Toshiya; Homma, Yoshiya*; Shiokawa, Yoshinobu*; Hirota, Kazuma*; Sato, Noriaki*
Journal of the Physical Society of Japan, 75(Suppl.), p.88 - 90, 2006/08
no abstracts in English
Amemiya, Hiroshi*; Wada, Motoi*; Toyoda, Hirotaka*; Nakamura, Keiji*; Ando, Akira*; Uehara, Kazuya; Oyama, Koichiro*; Sakai, Osamu*; Tachibana, Kunihide*
Purazuma, Kaku Yugo Gakkai-Shi, 81(7), p.482 - 525, 2005/07
This article is asked to write by the Japan Society of Plasma Science and Nuclear Fusion Research. The probe diagnostics in fusion plasma is explaind for many readers of the Journal of Plasma and Fusion Research, who have much concerned on various aspects.In section one, the method to estimate the electron temperature and the density as well as the electron energy distribution function with the single probe is given. In section two, the method to estimate the ion temperature and the flow velocity with the double probe is given. The practical measurements are explained introducing the data obtained at JFT-2, JFT-2a and JFT-2M in JAERI tokamak.
) by laser ablation in superfluid helium at 1.5KAratono, Yasuyuki; Wada, Akira*; Akiyama, Kazuhiko; Kitazawa, Shinichi; Hojo, Kiichi; Naramoto, Hiroshi*
Chemical Physics Letters, 408(4-6), p.247 - 251, 2005/06
Times Cited Count：1 Percentile：3(Chemistry, Physical)C fulleren was detected in the deposit produced by the laser ablation in superfluid helium at 1.5K. From the mass spectrometry, it was found that the ratio, 
C/C
C, differs from statistical one calculated by Poisson distribution for natural graphite. Assuming the recombination of atomic carbons to C molecules as an initial stage for C formation, the different isotopic ratio of C from Poisson statistics was ascribed to the tunneling recombination between C and C atoms in the bubble state.
Nishitani, Tomohiro; Nakanishi, Tsutomu*; Yamamoto, Masahiro*; Okumi, Shoji*; Furuta, Fumio*; Miyamoto, Masaharu*; Kuwahara, Makoto*; Yamamoto, Naoto*; Naniwa, Kenichi*; Watanabe, Osamu*; et al.
Journal of Applied Physics, 97(9), p.094907_1 - 094907_6, 2005/05
Times Cited Count：64 Percentile：87.31(Physics, Applied)no abstracts in English
and 5
vibrational bands of partially deuterated ammonia speciesAkagi, Hiroshi; Yokoyama, Keiichi; Yokoyama, Atsushi; Wada, Akira
Journal of Molecular Spectroscopy, 231(1), p.37 - 49, 2005/05
Times Cited Count：2 Percentile：11.62(Physics, Atomic, Molecular & Chemical)Absorption spectra of gaseous samples containing NHD and NHD have been measured in 11580-11880 and 15280-15610 cm
regions, corresponding to the 5 and 5 vibrational bands, respectively. Photoacoustic spectroscopy has been utilized for the measurement. The molecular constants of NHD in the 5 state and NHD in the 5 state have been determined by the analysis of the obtained absorption spectrum. Comparing the constants with those of the vibrational ground states, structural changes caused by the stretching excitations have been elucidated. The HND bond angles are decreased by these excitations. The dependence of the molecular constants on the stretching quantum number has been also derived by simple Birge-Sponer and Dunham analyses.
Nishitani, Takeo; Ochiai, Kentaro; Yoshida, Shigeo*; Tanaka, Ryohei*; Wakisaka, Masashi*; Nakao, Makoto*; Sato, Satoshi; Yamauchi, Michinori*; Hori, Junichi; Wada, Masayuki*; et al.
Journal of Nuclear Science and Technology, 41(Suppl.4), p.58 - 61, 2004/03
no abstracts in English
Yoshida, Shigeo*; Nishitani, Takeo; Ochiai, Kentaro; Kaneko, Junichi*; Hori, Junichi; Sato, Satoshi; Yamauchi, Michinori*; Tanaka, Ryohei*; Nakao, Makoto*; Wada, Masayuki*; et al.
Fusion Engineering and Design, 69(1-4), p.637 - 641, 2003/09
Times Cited Count：9 Percentile：53.35(Nuclear Science & Technology)no abstracts in English
Wada, Akira; Takayanagi, Toshiyuki; Shiga, Motoyuki
Journal of Chemical Physics, 119(11), p.5478 - 5486, 2003/09
Times Cited Count：22 Percentile：57.95(Chemistry, Physical)no abstracts in English
radical embedded in superfluid helium around 1.5 KWada, Akira; Aratono, Yasuyuki
Chemistry Letters, 32(2), p.200 - 201, 2003/02
Times Cited Count：6 Percentile：30.03(Chemistry, Multidisciplinary)no abstracts in English
He+H+H reactionTakayanagi, Toshiyuki; Wada, Akira
Chemical Physics, 277(3), p.313 - 323, 2002/04
Times Cited Count：6 Percentile：17.77(Chemistry, Physical)no abstracts in English
)+N(X
)
HCN(X
)+N(
S) reactionWada, Akira; Takayanagi, Toshiyuki
Journal of Chemical Physics, 116(16), p.7065 - 7072, 2002/04
Times Cited Count：10 Percentile：30.29(Chemistry, Physical)no abstracts in English
