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Journal Articles

NMR determination of noncollinear antiferromagnetic structure in TbCoGa$$_5$$

Tokunaga, Yo; Saito, Yo*; Sakai, Hironori; Kambe, Shinsaku; Sanada, Naoyuki*; Watanuki, Ryuta*; Suzuki, Kazuya*; Kawasaki, Yu*; Kishimoto, Yutaka*

Physical Review B, 84(21), p.214403_1 - 214403_7, 2011/12

 Times Cited Count:8 Percentile:36.26(Materials Science, Multidisciplinary)

We report NMR studies of TbCoGa$$_5$$, which has the tetragonal HoCoGa$$_5$$ structure and exhibits two antiferromagnetic (AF) transitions at $$T_{rm N1}$$=36.2 K and $$T_{rm N2}$$=5.4 K. From a symmetry analysis of internal magnetic fields at orthorhombic Ga sites, we have successfully determined the magnetic structures in the AF-I ($$T_{rm N2}<T<T_{rm N1}$$) and AF-II ($$T<T_{rm N2}$$) phases. The AF-I phase is a collinear AF order with a propagation vector $$q=[1/2, 0, 1/2]$$ and ordered moments parallel to the [001] direction. In the AF-II phase, on the other hand, we found a non-collinear AF structure described by double propagation vectors $$q_1=[1/2, 0, 1/2]$$ and $$q_{2}=[0, 1/2, 1/2]$$, where the moments tilt away from the [001] direction toward [100], keeping a constant value along the [001] direction. In the context of these results we discuss the possible presence of magnetic frustration in this system.

JAEA Reports

High density electric survey around the Horonobe Underground Research Laboratory, 3

Nakamura, Takahiro; Sanada, Hiroyuki; Sugita, Yutaka; Teshima, Minoru*; Kasagi, Toshio*; Kishimoto, Munemaru*; Deguchi, Tomonori*; Makuuchi, Ayumu*

JAEA-Research 2010-006, 68 Pages, 2010/06

JAEA-Research-2010-006.pdf:33.19MB

The present document is to report the result of geophysical survey by electric survey around a site proposed for the Horonobe Underground Research Laboratory Project at Horonobe-cho, Hokkaido by the Japan Atomic Energy Agency. This Electric survey using pole-pole array in Horonobe Underground Research Laboratory Area was the third survey. Resistivity distribution near surface was about 20 $$Omega$$$$cdot$$m and it become to about 2 $$Omega$$$$cdot$$m as the depth increasing. Resistivity distribution was good agreement with existing survey results and existing electrical resistivity log data. By comparing resistivity model with hydrology model, it was confirmed that resistivity reflected the density of salinity. The range and distribution trends of apparent resistivity in this year were similar to the results of last year. It is thought that the data in which reproducibility is high is acquired in this survey. The influence on the underground water flow by construction is not admitted now.

JAEA Reports

High density electric survey around the Horonobe Underground Research Laboratory, 2

Nakamura, Takahiro; Sanada, Hiroyuki; Sugita, Yutaka; Teshima, Minoru*; Kishimoto, Munemaru*; Matsuo, Koichi*

JAEA-Research 2008-102, 58 Pages, 2009/03

JAEA-Research-2008-102.pdf:48.97MB

The present document is to report the result of geophysical survey by electric survey around a site proposed for the Horonobe Underground Research Laboratory Project at Horonobe-cho, Hokkaido by the Japan Atomic Energy Agency. This Electric survey using pole-pole array in Horonobe Underground Research Laboratory Area was the second survey. Resistivity distribution near surface was about 20 ohm-m and it become to about 2 ohm-m as the depth increasing. Resistivity distribution was good agreement with existing survey results and existing electrical resistivity log data. By comparing resistivity model with hydrology model, it was confirmed that resistivity reflected the density of salinity. The range and distribution trends of apparent resistivity in this year were similar to the results of last year. It is thought that the data in which reproducibility is high is acquired in this survey. The influence on the underground water flow by construction is not admitted now.

Journal Articles

Progress in the ITER physics basis, 2; Plasma confinement and transport

Doyle, E. J.*; Houlberg, W. A.*; Kamada, Yutaka; Mukhovatov, V.*; Osborne, T. H.*; Polevoi, A.*; Bateman, G.*; Connor, J. W.*; Cordey, J. G.*; Fujita, Takaaki; et al.

Nuclear Fusion, 47(6), p.S18 - S127, 2007/06

no abstracts in English

Journal Articles

Study of impurity injection scenario in burning plasmas

Takenaga, Hidenobu; Kubo, Hirotaka; Kamada, Yutaka; Miura, Yukitoshi; Kishimoto, Yasuaki; Ozeki, Takahisa

Fusion Science and Technology, 50(4), p.503 - 507, 2006/11

 Times Cited Count:3 Percentile:24.14(Nuclear Science & Technology)

no abstracts in English

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:41.84(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

Generation of X-rays and energetic ions from superintense laser irradiation of micron-sized Ar clusters

Fukuda, Yuji; Akahane, Yutaka; Aoyama, Makoto; Inoue, Norihiro*; Ueda, Hideki; Kishimoto, Yasuaki; Yamakawa, Koichi; Faenov, A. Y.*; Magunov, A. I.*; Pikuz, T. A.*; et al.

Laser and Particle Beams, 22(3), p.215 - 220, 2004/07

 Times Cited Count:41 Percentile:78.99(Physics, Applied)

High resolution K-shell spectra of a plasma created by superintense laser irradiation of micron-sized Ar clusters have been measured with an intensity above 10$$^{19}$$ W/cm$$^2$$ and a pulse duration of 30 fs. The total photon flux of 2$$times$$10$$^8$$ photons/pulse was achieved for He$$_{alpha1}$$ resonant line of Ar ($$lambda$$=3.9491 AA , 3.14 keV). In parallel with X-ray measurements, energy distributions of emitted ions have been measured. The multiply-charged ions with kinetic energies up to 800 keV were observed. It is found that hot electrons produced by high contrast laser pulses allow the isochoric heating of clusters and shift the ion balance towards the higher charge states, which enhances both the X-ray line yield of the He-like argon ion and the ion kinetic energy.

Journal Articles

X-ray radiation of clusters irradiated by ultrafast, high-intensity laser pulses

Fukuda, Yuji; Akahane, Yutaka; Aoyama, Makoto; Inoue, Norihiro*; Ueda, Hideki; Kishimoto, Yasuaki; Yamakawa, Koichi; Faenov, A. Y.*; Magunov, A. I.*; Pikuz, T. A.*; et al.

Laser-Generated & Other Lab. X-Ray & EUV Sources (Proceedings of SPIE Vol.5196), p.234 - 243, 2004/00

High resolution X-ray emission spectra of plasma created by laser irradiation of rare-gas (Ar, Kr, Xe) clusters have been measured at laser intensities over 10$$^{19}$$ W/cm$$^2$$ and 30-fs pulse duration. To make these measurements possible, in addition to the effort to decrease a prepulse intensity using Pockels cell switches, micron-size clusters were produced using a specially designed conical nozzle. The Boltzmann equation and a detailed collisional radiative model are solved simultaneously as a function of time to model the time integrated X-ray spectra of the transient plasma. The results are quantitatively in good agreement with the experimentally observed X-ray emission spectra of Ar clusters.

Journal Articles

Optimized energetic particle emissions from Xe clusters in intense laser fields

Fukuda, Yuji; Yamakawa, Koichi; Akahane, Yutaka; Aoyama, Makoto; Inoue, Norihiro*; Ueda, Hideki; Kishimoto, Yasuaki

Physical Review A, 67(6), p.061201_1 - 061201_4, 2003/06

 Times Cited Count:56 Percentile:88.06(Optics)

We have probed the interaction of intense laser fields with Xe clusters by measuring the energy and charge state distributions of emitted ions and electrons using ultrafast 20 fs pulses. This work demonstrates that the energetic particle emissions from laser-cluster interactions can be optimized by manipulating the character of ultrafast laser pulses, i.e. pulse duration and sign of chirp.

Journal Articles

Proton and ion acceleration by an ultra-shortpulse sub peta-watt laser in deformed double-layer thin foils

Ueshima, Yutaka; Sentoku, Yasuhiko*; Kishimoto, Yasuaki

Nuclear Instruments and Methods in Physics Research A, 455(1), p.181 - 184, 2000/11

 Times Cited Count:17 Percentile:72.09(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Large-scale simulation system and advanced photon research

Ueshima, Yutaka; Kishimoto, Yasuaki

Proceedings of 3rd International Symposium on High Performance Computing, p.524 - 534, 2000/00

no abstracts in English

Journal Articles

Giga-Particle simulation on shot pulse photon and particle generation with ultra-shortpulse relativistic laser

Ueshima, Yutaka; Sentoku, Yasuhiko*; Kishimoto, Yasuaki

Proceedings of 4th International Conference on Supercomputing in Nuclear Applications (SNA 2000) (CD-ROM), 10 Pages, 2000/00

no abstracts in English

Journal Articles

Ion explosion and multi-mega-electron-volt ion generation from an underdense plasma layer irradiated by a relativistically intense short-pulse laser

Yamagiwa, Mitsuru; Koga, J. K.; L.N.Tsintsadze*; Ueshima, Yutaka*; Kishimoto, Yasuaki

Physical Review E, 60(5), p.5987 - 5990, 1999/11

 Times Cited Count:19 Percentile:63.05(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

Reduced transport and E$$_{R}$$ shearing in improved confinement regimes in JT-60U

Shirai, Hiroshi; Kikuchi, Mitsuru; Takizuka, Tomonori; Fujita, Takaaki; Koide, Yoshihiko; Rewoldt, G.*; Mikkelsen, D. R.*; Budny, R.*; Tang, W. M.*; Kishimoto, Yasuaki; et al.

Fusion Energy 1998, 2, p.405 - 412, 1999/00

no abstracts in English

Journal Articles

Giga-particle simulation on short pulse X ray generation with ultra-shortpulse relativistic laser

Ueshima, Yutaka*; Arakawa, Takuya*; Kishimoto, Yasuaki; Sasaki, Akira; Tajima, Toshiki*

Inst. Phys. Conf. Ser., (159), p.325 - 328, 1999/00

no abstracts in English

Journal Articles

Reduced transport and Er shearing in improved confinement regimes in JT-60U

Shirai, Hiroshi; Kikuchi, Mitsuru; Takizuka, Tomonori; Fujita, Takaaki; Koide, Yoshihiko; Rewoldt, G.*; Mikkelsen, D. R.*; Budny, R.*; Tang, W. M.*; Kishimoto, Yasuaki; et al.

Nuclear Fusion, 39(11Y), p.1713 - 1722, 1999/00

 Times Cited Count:67 Percentile:87.09(Physics, Fluids & Plasmas)

no abstracts in English

JAEA Reports

Generation of ultra-short pulse hard X-rays with ultra-short pulse intense laser

Ueshima, Yutaka*; Kishimoto, Yasuaki; Sasaki, Akira; Moribayashi, Kengo*; Nagashima, Keisuke; Kado, Masataka; Sagisaka, Akito*; Tajima, Toshiki*

JAERI-Research 98-048, 46 Pages, 1998/08

JAERI-Research-98-048.pdf:1.88MB

no abstracts in English

Journal Articles

Physics issues of high bootstrap current tokamaks

Ozeki, Takahisa; Azumi, Masafumi; Ishii, Yasutomo; Kishimoto, Yasuaki; G.Y.Fu*; Fujita, Takaaki; G.Rewoldt*; Kikuchi, Mitsuru; Kamada, Yutaka; Ide, Shunsuke; et al.

Plasma Physics and Controlled Fusion, 39(5A), p.A371 - A380, 1997/05

no abstracts in English

JAEA Reports

Studies on the dispersion of low-level liquid effluent released from the fuel reprocessing plant into the sea

*; *; *; Kitahara, Yoshihisa*; Kishimoto, Yoichiro; Yamato, Aiji; *; ; ; ; et al.

PNC TN841 78-69VOL1, 127 Pages, 1978/12

PNC-TN841-78-69VOL1.pdf:9.43MB

no abstracts in English

Oral presentation

Non-collinear antiferromagnetic structure in TbCoGa$$_5$$

Tokunaga, Yo; Saito, Yo*; Sakai, Hironori; Kambe, Shinsaku; Sanada, Naoyuki*; Watanuki, Ryuta*; Suzuki, Kazuya*; Kawasaki, Yu*; Kishimoto, Yutaka*

no journal, , 

We report NMR studies of TbCoGa$$_5$$, which has the tetragonal HoCoGa$$_5$$ structure and exhibits two antiferromagnetic (AF) transitions at $$T_{N1}$$=36.2 K and $$T_{N2}$$=5.4 K. From analysis of the internal fields at Ga sites, we have determined the magnetic structures of the AF-I ($$T_{N2}<T<T_{N1}$$) and the AF-II ($$T<T_{N2}$$) phases. The AF-I phase is a collinear AF order with the propagation vector q=[1/2, 0, 1/2] and with ordered moments parallel to the c axis. This is in accordance with the neutron diffraction measurements. In the AF-II phase, on the other hand, we found a non-collinear AF structure described with double propagation vectors $$q_1$$=[1/2, 0, 1/2] and $$q_2$$=[0, 1/2, 1/2]. Interestingly, the NMR reveals that the c component of the Tb moments does not change value between the AF-I and the AF-II phases, even though an a component is newly developed in the AF-II phase.

Oral presentation

Current situation of radionuclides analysis on Fukushima Daiichi Nuclear Power Station

Meguro, Yoshihiro; Kato, Jun; Kishimoto, Katsumi; Kameo, Yutaka; Ishimori, Kenichiro; Tanaka, Kiwamu; Shibata, Atsuhiro; Koma, Yoshikazu; Ashida, Takashi

no journal, , 

The authors are working in study for radioactive wastes generated in Fukushima Daiichi. Radioactive inventory estimation of wastes is important in the study for the processing and disposal of radioactive waste. And then so many real wastes have to be analyzed for their inventory evaluation. In addition to this waste analysis, there are several needs for analysis. For example a large volume of the contaminated water is being decontaminated, and operational status and ability of this system should be checked by analysis of the treated water. And also groundwater and sea water are analyzing to understand contaminated situation, to estimate a leakage position, and to confirm leakage prevention. In future fuel debris will be analyzed for its material accountancy. In this presentation, actual situation of analyses in Fukushima Daiichi will be explained, mainly focus on analyses for the inventory evaluation of the radioactive waste.

21 (Records 1-20 displayed on this page)