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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：4 Percentile：12.57(Environmental Sciences)
Si revealed by comparison with nonmagnetic references ThRuSi and LaRuSiEmi, Naoya*; Hamabata, Ryosuke*; Nakayama, Daisuke*; Miki, Toshihiro*; Koyama, Takehide*; Ueda, Koichi*; Mito, Takeshi*; Kohori, Yo*; Matsumoto, Yuji*; Haga, Yoshinori; et al.
Journal of the Physical Society of Japan, 84(6), p.063702_1 - 063702_4, 2015/06
Times Cited Count：10 Percentile：54.92(Physics, Multidisciplinary)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.
Kobayashi, Tetsuya; Michizono, Shinichiro*; Fang, Z.*; Matsumoto, Toshihiro*; Suzuki, Hiroyuki; Yamaguchi, Seiya*; Okada, Yoshihito*
Proceedings of 6th Annual Meeting of Particle Accelerator Society of Japan (CD-ROM), p.1068 - 1070, 2010/03
A 972-MHz RF system is being developed for 400-MeV upgrade of the J-PARC linac. The accelerating field stabilities should be less than 
1% in amplitude and 1
in phase. The basic digital LLRF (Low-Level RF) concept is the same as that of the present 324-MHz system with a compact-PCI crate. The main alterations are RF and clock generator (RF&CLK), mixer and I/Q modulator (IQ&Mixer) and digital LLRF algorithm. Since the typical decay time of the new system is faster (because its operational frequency is higher than that of the present 324-MHz cavity), chopped beam compensation is essential. The performance study of the digital feedback system with a cavity simulator is summarized.
Michizono, Shinichiro*; Fang, Z.*; Matsumoto, Toshihiro*; Yamaguchi, Seiya*; Kobayashi, Tetsuya; Okada, Yoshihito*
Proceedings of 2009 Particle Accelerator Conference (PAC '09) (DVD-ROM), p.2201 - 2203, 2009/05
Upgrade of J-PARC linac has been planed using 972 MHz rf system. The rf eld regulation is required to be less than 1% in amplitude and 1. in phase. The basic digital llrf concept is same as the present 324 MHz llrf system using a compact PCI crate. The main alterations are rf and clock generator (RF&LK), mixer and IQ modulator (IQ&Mixer) and digital llrf algorithm. Since the typical decay time is faster (due to higher operational frequency than present 324 MHz cavity), chopped beam compensation is one of the main concerns. Performance of the digital feedback system using a cavity simulator is summarized.
-Co films with giant tunnel magnetoresistanceMatsumoto, Yoshihiro; Sakai, Seiji; Takagi, Yasumasa*; Nakagawa, Takeshi*; Yokoyama, Toshihiko*; Shimada, Toshihiro*; Mitani, Seiji*; Naramoto, Hiroshi*; Maeda, Yoshihito
Chemical Physics Letters, 470(4-6), p.244 - 248, 2009/03
Times Cited Count：17 Percentile：48.66(Chemistry, Physical)Electronic and spin states of the codeposited C-Co films with large tunnel magnetoresistance (TMR) effect were investigated with the X-ray absorption and magnetic circular dichroism (MCD) spectroscopies. It is revealed that a C-Co compound generated in the C-Co films shows the clear MCD signal attributed to the spin-polarized Co 3d states hybridized with C 
orbitals. The magnetic response of these Co 3d-derived states agrees well with temperature dependence of the observed MR ratios of the granular C-Co films. This suggests the incorporation of the spin-polarized Co 3d-derived states of the C-Co compound into the observed TMR effect.
Michizono, Shinichiro*; Anami, Shozo*; Katagiri, Hiroaki*; Fang, Z.*; Matsumoto, Toshihiro*; Miura, Takako*; Yano, Yoshiharu*; Yamaguchi, Seiya*; Kobayashi, Tetsuya
Kasokuki, 5(2), p.127 - 136, 2008/07
One of the biggest advantages of the digital low level rf (LLRF) system is its flexibility. Owing to the recent rapid progress in digital devices (such as ADCs and DACs) and telecommunication devices (mixers and IQ modulators), digital LLRF system for accelerators becomes popular in these 10 years. The J-PARC linac LLRF system adopted cPCI crates and FPGA based digital feedback system. After the successful operation of J-PARC linac LLRF system, we developed the STF (ILC test facility in KEK) LLRF system. The future R&D projects (ILC and ERL) are also described from the viewpoints of LLRF.
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.
Matsumoto, Yoshihiro; Sakai, Seiji; Naramoto, Hiroshi*; Hirao, Norie*; Baba, Yuji; Shimada, Toshihiro*; Sugai, Isamu; Takanashi, Koki; Maeda, Yoshihito
Materials Research Society Symposium Proceedings, Vol.1081 (Internet), 6 Pages, 2008/03
Recently, we have found the appearance of substantial MR ratio (80%) in a C/Co hybrid material. Such the MR ratio cannot be explained enough only by tunnel conduction through Co grains. Therefore, to obtain information about electronic structures of C/Co hybrid material is necessary. Absorption spectra of CCo are different from that of pristine C. In particular, peak intensity corresponding to 
(LUMO) 
C 1s excitation of CCo is clearly attenuated. In addition, C 1s photoelectron peak of CCo slightly shifted to lower binding energy compared to that of pristine C. These results indicate that 3d electron of Co transfers to orbital of C and new electronic states are formed in the C-Co compound. In fact, XPS spectra of valence excitation region also demonstrate the formation of hybrid orbital near the Fermi level due to the coupling of C and Co.
Takeji, Satoru; Isayama, Akihiko; Ozeki, Takahisa; Tokuda, Shinji; Ishii, Yasutomo; Oikawa, Toshihiro; Ishida, Shinichi; Kamada, Yutaka; Neyatani, Yuzuru; Yoshino, Ryuji; et al.
Fusion Science and Technology (JT-60 Special Issue), 42(2-3), p.278 - 297, 2002/09
Times Cited Count：7 Percentile：3.03(Nuclear Science & Technology)no abstracts in English
Takeji, Satoru; Tokuda, Shinji; Fujita, Takaaki; Suzuki, Takahiro; Isayama, Akihiko; Ide, Shunsuke; Ishii, Yasutomo; Kamada, Yutaka; Koide, Yoshihiko; Matsumoto, Taro; et al.
Nuclear Fusion, 42(1), p.5 - 13, 2002/01
Times Cited Count：83 Percentile：89.59(Physics, Fluids & Plasmas)no abstracts in English
O reflectorHirota, Jitsuya; Kuroi, Hideo; Goto, Yorio; Furuhashi, Akira; Yasuno, Takehiko; Yamamoto, Ken; Mitani, Hiroshi; Obu, Makoto; Ichimori, Toshihiro; Koyama, Kinji; et al.
JAERI 1034, 50 Pages, 1962/08
no abstracts in English
-Co thin filmsMatsumoto, Yoshihiro; Sakai, Seiji; Entani, Shiro; Nakagawa, Takeshi*; Takagi, Yasumasa*; Nagamatsu, Shinichi*; Yokoyama, Toshihiko*; Shimada, Toshihiro*; Naramoto, Hiroshi*; Mitani, Seiji*; et al.
no journal, ,
no abstracts in English
Sakai, Seiji; Matsumoto, Yoshihiro; Entani, Shiro; Sugai, Isamu*; Takanashi, Koki; Takagi, Yasumasa*; Nakagawa, Takeshi*; Yokoyama, Toshihiko*; Shimada, Toshihiro*; Naramoto, Hiroshi*; et al.
no journal, ,
We investigated the bias-voltage (V) and temperature (T) dependences of the spin-dependent transport properties of the granular C60-Co films in the current perpendicular to plane (CPP) geometry. At low T, each sample shows much higher MR than the upper limit of TMR (MR=50%) derived from the Julliere's model. From the I-V characteristics, we evaluated the degree of the higher order tunneling process, as a possible cause of the MR enhancement above MR=50%, to be 3-7 (T=2K), which changes depending on the sample composition and device structure. By considering this enhancement effect, we can estimate the spin-polarization at the C60-Co compound/Co interface. The estimated values are remarkably high, i.e., P=75% at zero temperature, compared to Co crystal(P=30%), and almost independent of the samples. The detailed results on the transport properties and X-ray magnetic circular dichroism spectroscopy were presented in the conference.
-Co compound affecting giant TMR effect, 2Matsumoto, Yoshihiro; Sakai, Seiji; Entani, Shiro; Nagamatsu, Shinichi*; Hojo, Ikuko*; Fujikawa, Takashi*; Shimada, Toshihiro*; Naramoto, Hiroshi*; Maeda, Yoshihito; Yokoyama, Toshihiko*
no journal, ,
no abstracts in English
-Co compound / Ni layer structureMatsumoto, Yoshihiro; Entani, Shiro; Yokoyama, Toshihiko*; Shimada, Toshihiro*; Naramoto, Hiroshi*; Sakai, Seiji
no journal, ,
-Co compound / Ni bilayer thin filmMatsumoto, Yoshihiro; Entani, Shiro; Shimada, Toshihiro*; Naramoto, Hiroshi*; Mitani, Seiji*; Takanashi, Koki; Yokoyama, Toshihiko*; Sakai, Seiji
no journal, ,
no abstracts in English
Matsumoto, Yoshihiro; Entani, Shiro; Naramoto, Hiroshi*; Sakai, Seiji; Shimada, Toshihiro*; Yokoyama, Toshihiko*; Fujikawa, Takashi*
no journal, ,
no abstracts in English
-Co / Ni bilayer structure using X-ray magnetic circular dichroism analysisMatsumoto, Yoshihiro; Entani, Shiro; Shimada, Toshihiro*; Naramoto, Hiroshi*; Mitani, Seiji*; Takanashi, Koki; Yokoyama, Toshihiko*; Sakai, Seiji
no journal, ,
no abstracts in English
-Co compound / Ni bilayerMatsumoto, Yoshihiro; Entani, Shiro; Naramoto, Hiroshi*; Shimada, Toshihiro*; Yokoyama, Toshihiko*
no journal, ,
no abstracts in English
