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Kamiya, Junichiro; Kotoku, Hirofumi*; Kurosawa, Shunta*; Takano, Kazuhiro; Yanagibashi, Toru*; Yamamoto, Kazami; Wada, Kaoru
Physical Review Accelerators and Beams (Internet), 24(8), p.083201_1 - 083201_23, 2021/08
Times Cited Count：0 Percentile：0.02(Physics, Nuclear)Through the operation of the vacuum system in J-PARC, it becomes evident that the high-power beam has more powerful effects on the vacuum system than expected. Those effects are the malfunction of vacuum equipment and the large pressure rise. The former is the failure of the turbomolecular pump (TMP) controller. The TMP itself is also damaged by a bearing crush due to a touch-down. We have developed a TMP controller that can connect with long cables of more than 200 m lengths to install the controller in a control room where there is no radiation influence. The TMP with high-strength bearing has been also developed. The latter is an extreme pressure rise with increasing the beam power. It is indicated that the pressure rise mechanism is a result of ion-stimulated gas desorption. It is finally confirmed that the dynamic pressure during the high-power beam is effectually suppressed by additionally installing the NEG pumps.
Kamiya, Junichiro; Kotoku, Hirofumi; Hikichi, Yusuke*; Takahashi, Hiroki; Yamamoto, Kazami; Kinsho, Michikazu; Wada, Kaoru*
JPS Conference Proceedings (Internet), 33, p.011023_1 - 011023_6, 2021/03
The vacuum system is the key for the stable high power beam operation in J-PARC 3 GeV rapid cycling synchrotron (RCS), because the gas molecules in the beam line make the beam loss due to the scattering. The more than 10 years operation of the RCS vacuum system showed that the ultra-high vacuum (UHV) has been stably maintained by the several developments. The challenges for lower beam line pressure will exist in a future operation with higher beam power. For such challenge, a TMP with a rotor of titanium alloy, which have much higher mechanical strength than aluminum allow for the normal rotter, has been developed. Overcoming the difficulties of the machining performance of the titanium alloy rotor was successfully manufactured. We will report the summary of the 10 years operation of the RCS vacuum system and the incoming developments towards the XHV.
Nakajima, Kyo*; Teramoto, Takahiro*; Akagi, Hiroshi; Fujikawa, Takashi*; Majima, Takuya*; Minemoto, Shinichiro*; Ogawa, Kanade*; Sakai, Hirofumi*; Togashi, Tadashi*; Tono, Kensuke*; et al.
Scientific Reports (Internet), 5, p.14065_1 - 14065_11, 2015/09
Times Cited Count：38 Percentile：84.13(Multidisciplinary Sciences)We report on the measurement of deep inner-shell 2p X-ray photoelectron diffraction (XPD) patterns from laser-aligned I
molecules using X-ray free-electron laser (XFEL) pulses. The XPD patterns of the I molecules, aligned parallel to the polarization vector of the XFEL, were well matched with our theoretical calculations. Further, we propose a criterion for applying our molecular-structure-determination methodology to the experimental XPD data. In turn, we have demonstrated that this approach is a significant step toward the time-resolved imaging of molecular structures.
to extreme environmentsHorikawa, Daiki*; Yamaguchi, Ayami*; Sakashita, Tetsuya; Tanaka, Daisuke*; Hamada, Nobuyuki*; Yukuhiro, Fumiko*; Kuwahara, Hirokazu*; Kunieda, Takekazu*; Watanabe, Masahiko*; Nakahara, Yuichi*; et al.
Astrobiology, 12(4), p.283 - 289, 2012/04
Times Cited Count：23 Percentile：68.76(Astronomy & Astrophysics)We examined the hatchability of hydrated and anhydrobiotic eggs of the tardigrade to hatch after ionizing irradiation (helium ions), extremely low and high temperatures, and high vacuum. Anhydrobiotic eggs (50% lethal dose; 1690 Gy) were substantially more radioresistant than hydrated ones (50% lethal dose; 509 Gy). Anhydrobiotic eggs also have a broader temperature resistance compared with hydrated ones. Over 70% of the anhydrobiotic eggs treated at high and low temperatures, but all of the hydrated eggs failed to hatch. After exposure to high vacuum conditions, the hatchability of the anhydrobiotic eggs was comparable to that of untreated control eggs.
Inami, Toshiya; Michimura, Shinji; Mitsuda, Akihiro*; Wada, Hirofumi*
Physical Review B, 82(19), p.195133_1 - 195133_5, 2010/11
Times Cited Count：11 Percentile：46.11(Materials Science, Multidisciplinary)Two first-order phase transitions of the valence-fluctuating compound EuPtP at 
=246 K and 
=200 K were examined by means of resonant X-ray diffraction at the Eu 
absorption edge. Although previous M
ssbauer spectroscopy and preliminary X-ray diffraction experiments have suggested charge ordered states, characteristic energy spectra of the 111 and 11
reflections observed in the present experiment unambiguously indicated that twofold and threefold superstructures of Eu valence exist below and between and , respectively. We also propose a mechanism to explain the charge ordering in EuPtP based on a charge-lattice coupling that alters a Coulomb repulsion.
Sakanaka, Shogo*; Akemoto, Mitsuo*; Aoto, Tomohiro*; Arakawa, Dai*; Asaoka, Seiji*; Enomoto, Atsushi*; Fukuda, Shigeki*; Furukawa, Kazuro*; Furuya, Takaaki*; Haga, Kaiichi*; et al.
Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.2338 - 2340, 2010/05
Future synchrotron light source using a 5-GeV energy recovery linac (ERL) is under proposal by our Japanese collaboration team, and we are conducting R&D efforts for that. We are developing high-brightness DC photocathode guns, two types of cryomodules for both injector and main superconducting (SC) linacs, and 1.3 GHz high CW-power RF sources. We are also constructing the Compact ERL (cERL) for demonstrating the recirculation of low-emittance, high-current beams using above-mentioned critical technologies.
Matsuda, Yasuhiro*; Her, J. L.*; Inami, Toshiya; Owada, Kenji; Ouyang, Z. W.*; Okada, Kyoko*; Nojiri, Hiroyuki*; Mitsuda, Akihiro*; Wada, Hirofumi*; Yoshimura, Kazuyoshi*; et al.
Journal of Physics; Conference Series, 190, p.012019_1 - 012019_6, 2009/11
Times Cited Count：7 Percentile：85.24(Physics, Condensed Matter)Matsuda, Yasuhiro*; Ouyang, Z. W.*; Nojiri, Hiroyuki*; Inami, Toshiya; Owada, Kenji; Suzuki, Motohiro*; Kawamura, Naomi*; Mitsuda, Akihiro*; Wada, Hirofumi*
Physical Review Letters, 103(4), p.046402_1 - 046402_4, 2009/07
Times Cited Count：53 Percentile：87.11(Physics, Multidisciplinary)X-ray magnetic circular dichroism (XMCD) at the Eu L edge in two compounds exhibiting valence fluctuation, namely EuNi
(Si
Ge
) and EuNiP, has been investigated at high magnetic fields of up to 40T. A distinct XMCD peak corresponding to the trivalent state (Eu
), whose ground state is nonmagnetic (J = 0), was observed in addition to the main XMCD peak corresponding to the magnetic (J = 7/2) divalent state (Eu
). This result indicates that the 5
electrons belonging to both valence states are magnetically polarized. It was also found that the ratio 
(3+)/(2+) between the polarization of 5 electrons() in the Eu state and that of Eu depends on the material. The possible origin of the XMCD and an explanation of the material dependence of (3+)/(2+) are discussed in terms of hybridization between the conduction electrons and the f electrons.
Sakanaka, Shogo*; Ago, Tomonori*; Enomoto, Atsushi*; Fukuda, Shigeki*; Furukawa, Kazuro*; Furuya, Takaaki*; Haga, Kaiichi*; Harada, Kentaro*; Hiramatsu, Shigenori*; Honda, Toru*; et al.
Proceedings of 11th European Particle Accelerator Conference (EPAC '08) (CD-ROM), p.205 - 207, 2008/06
Future synchrotron light sources based on the energy-recovery linacs (ERLs) are expected to be capable of producing super-brilliant and/or ultra-short pulses of synchrotron radiation. Our Japanese collaboration team is making efforts for realizing an ERL-based hard X-ray source. We report recent progress in our R&D efforts.
(Si
Ge
)Matsuda, Yasuhiro*; Inami, Toshiya; Owada, Kenji; Murata, Yuto*; Nojiri, Hiroyuki*; Murakami, Yoichi*; Mitsuda, Akihiro*; Wada, Hirofumi*; Miyazaki, Hiroshi*; Harada, Isao*
Journal of the Physical Society of Japan, 77(5), p.054713_1 - 054713_7, 2008/05
Times Cited Count：25 Percentile：74.44(Physics, Multidisciplinary)The magnetic-field-induced valence transition in EuNi(SiGe) (x=0.82, 0.85) has been studied by X-ray absorption spectroscopy at low temperatures. The field dependence of the Eu valence is directly observed for the first time. We find a significant decrease in the valences at high magnetic fields above 40 T. The valence of Eu changes from v = 2.75 at a zero field to v = 2.33 at 40 T for x = 0.82. The results are analyzed using a theoretical model. The hybridization parameter V between the Eu and Eu states and the energy separation 
are determined, which are crucial for quantum mechanical mixing.
Ru
O
thin filmsTerai, Kota*; Yoshii, Kenji; Takeda, Yukiharu; Fujimori, Shinichi; Saito, Yuji; Owada, Kenji; Inami, Toshiya; Okane, Tetsuo; Arita, Masashi*; Shimada, Kenya*; et al.
Physical Review B, 77(11), p.115128_1 - 115128_6, 2008/03
Times Cited Count：15 Percentile：54.78(Materials Science, Multidisciplinary)RuO thin filmsTerai, Kota; Yoshii, Kenji; Takeda, Yukiharu; Fujimori, Shinichi; Saito, Yuji; Owada, Kenji; Inami, Toshiya; Okane, Tetsuo; Arita, Masashi*; Shimada, Kenya*; et al.
Journal of Magnetism and Magnetic Materials, 310(2, Part2), p.1070 - 1072, 2007/03
We have studied the electronic and magnetic properties of epitaxially grown CaMnRuO (x = 1.0, 0.5) thin films by X-ray magnetic circular dichroism (XMCD) and hard X-ray photoemission spectroscopy (HXPES). The XMCD studies indicated that the spin moments of Mn and Ru are aligned in the opposite directions. The HXPES spectra indicated the Ru 4d states at around the Fermi edge (E
) and the Mn 3d states below E. From these results, we propose that the localized Mn 3d t
states and the itinerant Ru 4d t band are antiferromagnetically coupled and give rise to ferromagnetism, in analogy with the mechanism proposed for the double perovskite oxides such as SrFeMoO
.
Matsuda, Yasuhiro*; Murata, Yuto*; Inami, Toshiya; Owada, Kenji; Nojiri, Hiroyuki*; Oyama, Kenji*; Kato, Naoki*; Murakami, Yoichi*; Iga, Fumitoshi*; Takabatake, Toshiro*; et al.
Journal of Physics; Conference Series, 51, p.490 - 493, 2006/00
Times Cited Count：8 Percentile：92.36(Physics, Condensed Matter)RuOTerai, Kota; Okane, Tetsuo; Takeda, Yukiharu; Fujimori, Shinichi; Saito, Yuji; Yoshii, Kenji; Owada, Kenji; Inami, Toshiya; Arita, Masashi*; Shimada, Kenya*; et al.
no journal, ,
no abstracts in English
Takeda, Yukiharu; Fujimori, Shinichi; Okane, Tetsuo; Saito, Yuji; Yamagami, Hiroshi; Kobayashi, Keisuke*; Inami, Toshiya; Owada, Kenji; Arita, Masashi*; Shimada, Kenya*; et al.
no journal, ,
no abstracts in English
Inami, Toshiya; Michimura, Shinji; Mitsuda, Akihiro*; Wada, Hirofumi*
no journal, ,
no abstracts in English
Inami, Toshiya; Michimura, Shinji; Mitsuda, Akihiro*; Wada, Hirofumi*
no journal, ,
Kamiya, Junichiro; Yamamoto, Kazami; Takano, Kazuhiro; Kotoku, Hirofumi; Wada, Kaoru*; Yanagibashi, Toru*; Kurosawa, Shunta*
no journal, ,
The vacuum system in the rapid cycling synchrotron of Japan Proton Accelerator Research Complex was constructed based on the design concept considering the effect of a dynamic pressure caused by a high-power proton beam operation. However, the high-power beam operation clearly has more effects than expected at the time of the design. The dynamic pressure with the beamline pressure runaway characterized by an extreme pressure rise of more than orders of magnitude occurred during beam operation. A systematic data observation showed that the pressure rise mechanism is a result of the gas desorption from the wall triggered by the hitting of the residual gas molecules ionized by the proton beam. The numerical calculation based on that model well reproduced the measured dynamic pressure behaviors in the beam operation. The calculation also showed that a large pumping speed and a small surface density of the adsorbed molecules are required to suppress the pressure runaway.
