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Journal Articles

$$omega N$$ scattering length from $$omega$$ photoproduction on the proton near the reaction threshold

Ishikawa, Takatsugu*; Fujimura, Hisako*; Fukasawa, Hiroshi*; Hashimoto, Ryo*; He, Q.*; Honda, Yuki*; Hosaka, Atsushi; Iwata, Takahiro*; Kaida, Shun*; Kasagi, Jirota*; et al.

Physical Review C, 101(5), p.052201_1 - 052201_6, 2020/05

 Times Cited Count:4 Percentile:45.12(Physics, Nuclear)

Journal Articles

Termination of electron acceleration in thundercloud by intracloud/intercloud discharge

Wada, Yuki*; Bowers, G. S.*; Enoto, Teruaki*; Kamogawa, Masashi*; Nakamura, Yoshitaka*; Morimoto, Takeshi*; Smith, D.*; Furuta, Yoshihiro*; Nakazawa, Kazuhiro*; Yuasa, Takayuki*; et al.

Geophysical Research Letters, 45(11), p.5700 - 5707, 2018/06

 Times Cited Count:31 Percentile:81.84(Geosciences, Multidisciplinary)

Journal Articles

In situ neutron diffraction study on microstructure evolution during thermo-mechanical processing of medium manganese steel

Nakamura, Yoshihiko*; Shibata, Akinobu*; Gong, W.*; Harjo, S.; Kawasaki, Takuro; Ito, Atsushi*; Tsuji, Nobuhiro*

Proceedings of International Conference on Martensitic Transformations: Chicago, p.155 - 158, 2018/04

Journal Articles

Retreat from stress; Rattling in a planar coordination

Suekuni, Koichiro*; Lee, C. H.*; Tanaka, Hiromi*; Nishibori, Eiji*; Nakamura, Atsushi*; Kasai, Hidetaka*; Mori, Hitoshi*; Usui, Hidetomo*; Ochi, Masayuki*; Hasegawa, Takumi*; et al.

Advanced Materials, 30(13), p.1706230_1 - 1706230_6, 2018/03

 Times Cited Count:51 Percentile:89.35(Chemistry, Multidisciplinary)

Thermoelectric materials for highly efficient devices must satisfy conflicting requirements of high electrical conductivity and low thermal conductivity. In this paper, we studied the crystal structure and phonon dynamics of tetrahedrites (Cu,Zn)$$_{12}$$(Sb,As)$$_{4}$$S$$_{13}$$. The results revealed that the Cu atoms in a planar coordination are rattling, which effectively scatter phonons. These findings provide a new strategy for the development of highly efficient thermoelectric materials with planar coordination.

Journal Articles

Effect of rattling motion without cage structure on lattice thermal conductivity in LaOBiS$$_{2-x}$$Se$$_x$$

Lee, C. H.*; Nishida, Atsuhiro*; Hasegawa, Takumi*; Nishiate, Hirotaka*; Kunioka, Haruno*; Kawamura, Seiko; Nakamura, Mitsutaka; Nakajima, Kenji; Mizuguchi, Yoshikazu*

Applied Physics Letters, 112(2), p.023903_1 - 023903_4, 2018/01

 Times Cited Count:28 Percentile:77.9(Physics, Applied)

Low energy phonons in LaOBiS$$_{2-x}$$Se$$_x$$ are studied using inelastic neutron scattering. Dispersionless flat phonon branches that are mainly associated with a large vibration of Bi atoms are observed at a relatively low energy of $$E$$ = 6 - 6.7 meV. The phonon energy softens upon Se doping owing to its heavier atomic mass than S atom and the expansion of lattice constant. Simultaneously, the lattice thermal conductivity lowered upon Se doping as the same manner of the phonon softening. These suggest that despite the lack of an oversized cage in LaOBiS$$_{2-x}$$Se$$_x$$, rattling motions of Bi atoms can scatter phonon like rattling in cage compounds, contributing to enhance the thermoelectric property.

Journal Articles

Activation, Radiation shielding materials

Sukegawa, Atsuhiko; Iida, Hiromasa*; Itoga, Toshio*; Okumura, Keisuke; Kai, Tetsuya; Konno, Chikara; Nakashima, Hiroshi; Nakamura, Takashi*; Ban, Shuichi*; Yashima, Hiroshi*; et al.

Hoshasen Shahei Handobukku; Kisohen, p.299 - 356, 2015/03

no abstracts in English

Journal Articles

In-vessel tritium

Ueda, Yoshio*; Oya, Kaoru*; Ashikawa, Naoko*; Ito, Atsushi*; Ono, Tadayoshi*; Kato, Daiji*; Kawashima, Hisato; Kawamura, Gakushi*; Kenmotsu, Takahiro*; Saito, Seiki*; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 88(9), p.484 - 502, 2012/09

no abstracts in English

Journal Articles

Identified charged hadron production in $$p + p$$ collisions at $$sqrt{s}$$ = 200 and 62.4 GeV

Adare, A.*; Afanasiev, S.*; Aidala, C.*; Ajitanand, N. N.*; Akiba, Yasuyuki*; Al-Bataineh, H.*; Alexander, J.*; Aoki, Kazuya*; Aphecetche, L.*; Armendariz, R.*; et al.

Physical Review C, 83(6), p.064903_1 - 064903_29, 2011/06

 Times Cited Count:184 Percentile:99.44(Physics, Nuclear)

Transverse momentum distributions and yields for $$pi^{pm}, K^{pm}, p$$, and $$bar{p}$$ in $$p + p$$ collisions at $$sqrt{s}$$ = 200 and 62.4 GeV at midrapidity are measured by the PHENIX experiment at the RHIC. We present the inverse slope parameter, mean transverse momentum, and yield per unit rapidity at each energy, and compare them to other measurements at different $$sqrt{s}$$ collisions. We also present the scaling properties such as $$m_T$$ and $$x_T$$ scaling and discuss the mechanism of the particle production in $$p + p$$ collisions. The measured spectra are compared to next-to-leading order perturbative QCD calculations.

Journal Articles

Azimuthal correlations of electrons from heavy-flavor decay with hadrons in $$p+p$$ and Au+Au collisions at $$sqrt{s_{NN}}$$ = 200 GeV

Adare, A.*; Afanasiev, S.*; Aidala, C.*; Ajitanand, N. N.*; Akiba, Yasuyuki*; Al-Bataineh, H.*; Alexander, J.*; Aoki, Kazuya*; Aphecetche, L.*; Aramaki, Y.*; et al.

Physical Review C, 83(4), p.044912_1 - 044912_16, 2011/04

 Times Cited Count:8 Percentile:49.7(Physics, Nuclear)

Measurements of electrons from the decay of open-heavy-flavor mesons have shown that the yields are suppressed in Au+Au collisions compared to expectations from binary-scaled $$p+p$$ collisions. Here we extend these studies to two particle correlations where one particle is an electron from the decay of a heavy flavor meson and the other is a charged hadron from either the decay of the heavy meson or from jet fragmentation. These measurements provide more detailed information about the interaction between heavy quarks and the quark-gluon matter. We find the away-side-jet shape and yield to be modified in Au+Au collisions compared to $$p+p$$ collisions.

Journal Articles

Power coupler development for ERL main linac in Japan

Sakai, Hiroshi*; Furuya, Takaaki*; Sakanaka, Shogo*; Takahashi, Takeshi*; Umemori, Kensei*; Ishii, Atsushi*; Nakamura, Norio*; Shinoe, Kenji*; Sawamura, Masaru

Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.2953 - 2955, 2010/05

We started to develop an input power coupler for a 1.3 GHz ERL superconducting cavity for main linac. We fabricated power coupler components such as ceramic windows and bellows and carried out the high-power test of the components by using a CW 30 kW IOT power source. During this test, the ceramic window was broken by the sudden heat load. We found that this heat load occurred by the unexpected dipole mode. We renewed the ceramic window and successfully carried out the high power test up to CW 27 kW input power.

Journal Articles

Development of a TES microcalorimeter for spectroscopic measurement of LX-rays emitted by transuranium elements

Maehata, Keisuke*; Nakamura, Keisuke*; Yasumune, Takashi*; Ishibashi, Kenji*; Takasaki, Koji; Tanaka, Keiichi*; Odawara, Akikazu*; Nagata, Atsushi*

Journal of Nuclear Science and Technology, 47(3), p.308 - 313, 2010/03

 Times Cited Count:5 Percentile:35.74(Nuclear Science & Technology)

A phase transition edge sensor (TES) microcalorimeter was developed for the energy dispersive measurement of LX-ray photons emitted from transuranium elements. The phase transition temperature of the TES was designed to be 200 mK by using bilayer structure of Au of 120 nm thick and Ti of 50 nm thick. The Au layer of 5.0 $$mu$$m thick was deposited on the Au/Ti bilayer for absorption efficiency of 50% and counting rate of 100 counts per second in the detection of LX-ray photons with the energy from 10 to 20 keV. The TES microcalorimeter was operated for the detection of LX-ray photons emitted from $$^{241}$$Am, $$^{238}$$Pu and $$^{239}$$Pu sources. The decay time constant of 180 $$mu$$s of detection signal pulses allowed the TES microcalorimeter operating with the counting rate higher than 100 counts per second. The energy resolution was obtained to be 50 eV of FWHM value for a peak corresponding to $$^{237}$$Np L$$beta$$$$_{1}$$ X-ray of 17.75 keV.

Journal Articles

Development of 20 kW input power coupler for 1.3 GHz ERL main linac; Component test at 30 kW IOT test stand

Sakai, Hiroshi*; Umemori, Kensei*; Sakanaka, Shogo*; Takahashi, Takeshi*; Furuya, Takaaki*; Shinoe, Kenji*; Ishii, Atsushi*; Nakamura, Norio*; Sawamura, Masaru

Proceedings of 6th Annual Meeting of Particle Accelerator Society of Japan (CD-ROM), p.866 - 868, 2010/03

We started to develop an input coupler for a 1.3 GHz ERL superconducting cavity. Required input power is about 20 kW for the cavity acceleration field of 20 MV/m and the beam current of 100 mA in energy recovery operation. The input coupler is designed based on the STF-BL input coupler and some modifications are applied to the design for the CW 20 kW power operation. We fabricated input coupler components such as ceramic windows and bellows and carried out the high-power test of the components by using a 30 kW IOT power source and a test stand constructed for the high-power test. In this report, we mainly describe the results of the high-power test of ceramic window and bellows.

Journal Articles

Tritium science and technology for fusion reactor, 3; Theory and code development for evaluation of tritium retention and exhaust in fusion reactor

Oya, Kaoru*; Inai, Kensuke*; Shimizu, Katsuhiro; Takizuka, Tomonori; Kawashima, Hisato; Hoshino, Kazuo; Hatayama, Akiyoshi*; Toma, Mitsunori*; Tomita, Yukihiro*; Kawamura, Gakushi*; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 85(10), p.695 - 703, 2009/10

no abstracts in English

Journal Articles

Development of input power coupler for ERL main linac in Japan

Sakai, Hiroshi*; Furuya, Takaaki*; Sakanaka, Shogo*; Takahashi, Takeshi*; Umemori, Kensei*; Ishii, Atsushi*; Nakamura, Norio*; Shinoe, Kenji*; Sawamura, Masaru

Proceedings of 14th International Conference on RF Superconductivity (SRF 2009) (Internet), p.684 - 688, 2009/09

We started to develop an input coupler for a 1.3GHz ERL superconducting cavity for ERL main linac. Required input power is about 20kW for the cavity acceleration field of 20MV/m and the beam current of 100mA in energy recovery operation. The input coupler is designed based on the STF-BL input coupler and some modifications are applied for the CW 20kW power operation. We fabricated input coupler components such as ceramic windows and bellows and carried out the high-power test of the components by using a 30kW IOT power source and a test stand constructed.

Journal Articles

Progress in R&D efforts on the energy recovery linac in Japan

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.

Journal Articles

Overview of national centralized tokamak program; Mission, design and strategy to contribute ITER and DEMO

Ninomiya, Hiromasa; Akiba, Masato; Fujii, Tsuneyuki; Fujita, Takaaki; Fujiwara, Masami*; Hamamatsu, Kiyotaka; Hayashi, Nobuhiko; Hosogane, Nobuyuki; Ikeda, Yoshitaka; Inoue, Nobuyuki; et al.

Journal of the Korean Physical Society, 49, p.S428 - S432, 2006/12

To contribute DEMO and ITER, the design to modify the present JT-60U into superconducting coil machine, named National Centralized Tokamak (NCT), is being progressed under nationwide collaborations in Japan. Mission, design and strategy of this NCT program is summarized.

Journal Articles

Overview of the national centralized tokamak programme

Kikuchi, Mitsuru; Tamai, Hiroshi; Matsukawa, Makoto; Fujita, Takaaki; Takase, Yuichi*; Sakurai, Shinji; Kizu, Kaname; Tsuchiya, Katsuhiko; Kurita, Genichi; Morioka, Atsuhiko; et al.

Nuclear Fusion, 46(3), p.S29 - S38, 2006/03

 Times Cited Count:13 Percentile:41.76(Physics, Fluids & Plasmas)

The National Centralized Tokamak (NCT) facility program is a domestic research program for advanced tokamak research to succeed JT-60U incorporating Japanese university accomplishments. The mission of NCT is to establish high beta steady-state operation for DEMO and to contribute to ITER. The machine flexibility and mobility is pursued in aspect ratio and shape controllability, feedback control of resistive wall modes, wide current and pressure profile control capability for the demonstration of the high-b steady state.

Journal Articles

Engineering design and control scenario for steady-state high-beta operation in national centralized tokamak

Tsuchiya, Katsuhiko; Akiba, Masato; Azechi, Hiroshi*; Fujii, Tsuneyuki; Fujita, Takaaki; Fujiwara, Masami*; Hamamatsu, Kiyotaka; Hashizume, Hidetoshi*; Hayashi, Nobuhiko; Horiike, Hiroshi*; et al.

Fusion Engineering and Design, 81(8-14), p.1599 - 1605, 2006/02

 Times Cited Count:1 Percentile:9.98(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Design study of national centralized tokamak facility for the demonstration of steady state high-$$beta$$ plasma operation

Tamai, Hiroshi; Akiba, Masato; Azechi, Hiroshi*; Fujita, Takaaki; Hamamatsu, Kiyotaka; Hashizume, Hidetoshi*; Hayashi, Nobuhiko; Horiike, Hiroshi*; Hosogane, Nobuyuki; Ichimura, Makoto*; et al.

Nuclear Fusion, 45(12), p.1676 - 1683, 2005/12

 Times Cited Count:15 Percentile:45.53(Physics, Fluids & Plasmas)

Design studies are shown on the National Centralized Tokamak facility. The machine design is carried out to investigate the capability for the flexibility in aspect ratio and shape controllability for the demonstration of the high-beta steady state operation with nation-wide collaboration, in parallel with ITER towards DEMO. Two designs are proposed and assessed with respect to the physics requirements such as confinement, stability, current drive, divertor, and energetic particle confinement. The operation range in the aspect ratio and the plasma shape is widely enhanced in consistent with the sufficient divertor pumping. Evaluations of the plasma performance towards the determination of machine design are presented.

Journal Articles

Acoustic emission and disturbances in central solenoid model coil for international thermonuclear experimental reactor

Arai, K.*; Ninomiya, Akira*; Ishigooka, Takeshi*; Takano, Katsutoshi*; Nakajima, Hideo; Michael, P.*; Vieira, R.*; Martovetsky, N.*; Sborchia, C.*; Alekseev, A.*; et al.

Cryogenics, 44(1), p.15 - 27, 2004/01

 Times Cited Count:3 Percentile:15.47(Thermodynamics)

no abstracts in English

30 (Records 1-20 displayed on this page)