Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Machida, Akihiko; Honda, Mitsunori*; Hattori, Takanori; Sano, Asami; Watanuki, Tetsu; Katayama, Yoshinori; Aoki, Katsutoshi; Komatsu, Kazuki*; Arima, Hiroshi*; Oshita, Hidetoshi*; et al.
Physical Review Letters, 108(20), p.205501_1 - 205501_5, 2012/05
Times Cited Count：17 Percentile：67.41(Physics, Multidisciplinary)Hydrogen atoms absorbed in a metal occupy the interstitial sites of the metal lattice. In an fcc metal lattice, each metal atom has two tetrahedral (T) and one octahedral (O) sites that can accommodate hydrogen. Rare-earth metal La forms T-site occupied LaH
and fully occupied LaH
. O-site occupied or NaCl-type monohydride has yet to be reported for rare-earth metals. Previous X-ray diffraction measurements revealed the pressure-induced decomposition of an fcc-LaH
into H-rich and H-poor phases around 11 GPa. The present neutron diffraction measurements on LaD confirm the formation of NaCl-type LaD as a counterpart of the D-rich LaD
by disproportionation. First-principle calculations demonstrate that the NaCl-type LaH is stabilized at high pressures. Finding the NaCl-type LaH will pave the way for investigations on the site-dependent nature of hydrogen-metal interactions.
Kamakura, Nozomu; Takeda, Yukiharu; Saito, Yuji; Yamagami, Hiroshi; Tsubota, Masami*; Paik, B.*; Ichikawa, Takayuki*; Kojima, Yoshitsugu*; Muro, Takayuki*; Kato, Yukako*; et al.
Physical Review B, 83(3), p.033103_1 - 033103_4, 2011/01
Times Cited Count：5 Percentile：25.35(Materials Science, Multidisciplinary)The electronic structure of lithium amide, which is lightweight complex hydride expected as a high-capacity hydrogen storage material, is investigated by N 1
soft X-ray emission spectroscopy (XES) and absorption spectroscopy (XAS). The overall feature of the electronic structure of lithium amide by the XES and XAS is consistent with the band calculation, while the strongly hybridized state with H 1 is located at higher binding energy than the band calculation.
Ao, Hiroyuki; Asano, Hiroyuki; Ouchi, Nobuo; Tsubota, Naoaki; Hasegawa, Kazuo; Hirano, Koichiro; Morishita, Takatoshi; Takata, Koji*; Naito, Fujio*; Yamazaki, Yoshishige
Proceedings of 7th Annual Meeting of Particle Accelerator Society of Japan (DVD-ROM), p.552 - 554, 2010/08
The energy upgrade of the J-PARC linac was started from March 2009. In this project 20 Annular Coupled Structure (ACS) modules will be fabricated. The resonant frequency of the ACS module has to be tuned with mechanical machining before the final brazing. Therefore the test cells were fabricated to accumulate frequency tuning parameters. We fixed the final dimensions and the machining amount of the frequency tuning using these results. So far, the cell parts for the five ACS modules were tuned within 71.93 
0.05 MHz. At the moment the first ACS module is being assembled and it will be completed in autumn 2010.
Ao, Hiroyuki; Asano, Hiroyuki; Ouchi, Nobuo; Tsubota, Naoaki; Hasegawa, Kazuo; Hirano, Koichiro; Morishita, Takatoshi; Takata, Koji*; Naito, Fujio*; Yamazaki, Yoshishige
Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.618 - 620, 2010/05
The mass production of the ACS (Annular-ring Coupled Structure) cavity started from March 2009 for the J-PARC linac energy upgrade from 181 MeV to 400 MeV. This upgrade project requires 18 ACS accelerating modules and two debunchers additionally within three years. The schedule is so tight that we have to optimize the fabrication process. Thus the test cells were fabricated for the all geometrical beta before the mass production to confirm the initial design and the frequency tuning procedure. This paper describes our approach for the mass production and the current status.
-edgesIshimatsu, Naoki*; Sasada, Ryohei*; Maruyama, Hiroshi*; Ichikawa, Takayuki*; Miyaoka, Hiroki*; Kimura, Toru*; Tsubota, Masami*; Kojima, Yoshitsugu*; Tsumuraya, Takao*; Oguchi, Tamio*; et al.
Journal of Physics; Conference Series, 190, p.012070_1 - 012070_4, 2009/11
Times Cited Count：5 Percentile：79.33(Physics, Condensed Matter)We have investigated the effect of hydrogenation on La 
and 
electronic states in metallic LaH
by X-ray absorption near edge structure at the La -edges. As the hydrogen content 
increases from 0 to 2.6, white-line intensity at the La 
-edges shows a remarkable increase in the range of 
2.0. This is interpreted as the increase in La hole induced by interstitial H atoms on the octahedral sites. On the other hand, the shoulder structure at the La 
-edge disappears in the process of = 0.0 
2.0, indicating that the 
-
hybridization is weakened by H atoms on the tetrahedral sites. This study demonstrates that H atoms on the two interstitial H sites provide different contribution to the modification of the electronic states.
Ga
(=Ni, Pd, and Pt)Kuzushita, Kaori*; Ishii, Kenji; Wilkins, S. B.*; Janousova, B.*; Inami, Toshiya; Owada, Kenji; Tsubota, Masami; Murakami, Yoichi; Kaneko, Koji; Metoki, Naoto; et al.
Physical Review B, 73(10), p.104431_1 - 104431_5, 2006/03
Times Cited Count：8 Percentile：38.44(Materials Science, Multidisciplinary)We report a resonant X-ray scattering study of antiferromagnetic uranium compounds UGa (=Ni, Pd, and Pt) at the Ga 
-edge. A large resonant signal is observed below the N
el temperatures. The azimuth dependence in both 
-
and -
polarization channels establishes that the resonant signal has the symmetry of the magnetic dipole. This resonance with the band electrons is interpreted within a semi-localized model as an orbital polarization of the Ga 
states induced through strong hybridization with U 
valence level. These results demonstrate that resonant magnetic X-ray scattering at the anions, taken in combination with symmetry arguments, can be used to determine the configuration of the U moments and provide information about the hybridization.
Hama, Katsuhiro; Yoshida, Hidekazu; Tsubota, Koji
JNC TN7450 99-001, 287 Pages, 1999/03
no abstracts in English
Tsubota, Koji
JNC TN7410 99-001, 348 Pages, 1999/03
JNC-TN7410-99-001.pdf:11.36MBJNC-TN7410-99-001(errata).pdf:0.08MB
None
Yoshida, Hidekazu; Tsubota, Koji; ; Hama, Katsuhiro; Metcalf
Nachuraru Anarogu Semmonka Kaigi (EC-NAWG), 0 Pages, 1999/00
None
Tsubota, Koji*; Ochiai, Yoji*; Hasegawa, Ken*; Nagasaki, Yasushi*; Yamagishi, Akiko*; Nakano, Katsushi*; Muneto, Masaru*
JNC TN7400 2005-021, 166 Pages, 1995/04
JNC-TN7400-2005-021.PDF:7.06MB
None
Tsubota, Koji*; Ochiai, Yoji*; Hanaki, Tatsumi*; Hasegawa, Ken*; Okita, Masatoshi*; Koide, Kaoru*; Nagasaki, Yasushi*
JNC TN7400 2005-019, 114 Pages, 1993/04
JNC-TN7400-2005-019.PDF:7.46MB
None
Kamakura, Nozomu; Takeda, Yukiharu; Saito, Yuji; Yamagami, Hiroshi; Tsubota, Masami*; Paik, B.*; Ichikawa, Takayuki*; Kojima, Yoshitsugu*; Muro, Takayuki*; Kinoshita, Toyohiko*
no journal, ,
Lithium amide (LiNH) is lightweight complex hydride expected as a high-capacity hydrogen storage material. The electronic structure of lithium amide (LiNH) is investigated by soft X-ray emission spectroscopy (XES) and absorption spectroscopy (XAS). The unoccupied and occupied parts of the N 2 partial density of states are studied by N 1 XAS in the fluorescence yield mode and XES using soft X-ray (h
=425eV) of SPring-8. The XES and XAS spectra show a band gap between the valence and conduction bands. The valence band in the XES spectrum consists of three peaks, which extend up to 
-8eV from the valence band top. The overall feature of the electronic structure of lithium amide by the XES and XAS is consistent with the band calculation. The strongly hybridized state with H 1 observed on the high binding energy side in the XES is discussed.
