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Journal Articles

ToF inelastic neutron scattering studies on quantum spin systems (CuCl)La$$B_2$$O$$_7$$ ($$B$$ = Nb, Ta)

Kawamura, Seiko; Nakajima, Kenji; Inamura, Yasuhiro; Tsujimoto, Yoshihiro*; Kitada, Atsushi*; Takeiri, Fumitaka*; Kageyama, Hiroshi*; Ajiro, Yoshitami*; Nishi, Masakazu*; Kakurai, Kazuhisa

Journal of Physics; Conference Series, 320, p.012037_1 - 012037_5, 2011/09

 Times Cited Count:0 Percentile:100

The magnetic ground state of (CuCl)LaNb$$_2$$O$$_7$$ has been suggested to be a spin-singlet state with an excitation gap of $$Delta E sim 2.3$$ meV, while (CuCl)LaTa$$_2$$O$$_7$$ has an antiferromagnetic (AFM) ground state. The systems are suspected to be a frustrated quantum spin system due to the competition between the nearest and next-nearest exchange interactions. We have studied magnetic excitation in these systems by ToF inelastic neutron scattering technique. The measurements were performed on powder samples of (CuCl)LaNb$$_2$$O$$_7$$ and (CuCl)LaTa$$_2$$O$$_7$$ at a disk-chopper-type spectrometer AMATERAS in J-PARC. In both systems, a band-like excitation was observed at $$Delta E sim 2$$ meV. The $$Q$$ dependence of the intensity of magnetic excitation around 2 meV for (CuCl)LaNb$$_2$$O$$_7$$ well reproduces that observed at a triple-axis spectrometer, exhibiting characteristics of spin-singlet dimers. On the other hand, (CuCl)LaTa$$_2$$O$$_7$$ in the AFM state exhibits a different $$Q$$ dependence.

Journal Articles

Neutron diffraction studies on the multiferroic conical magnet Ba$$_{2}$$Mg$$_{2}$$Fe$$_{12}$$O$$_{22}$$

Ishiwata, Shintaro*; Okuyama, Daisuke*; Kakurai, Kazuhisa; Nishi, Masakazu*; Taguchi, Yasujiro*; Tokura, Yoshinori*

Physical Review B, 81(17), p.174418_1 - 174418_8, 2010/05

 Times Cited Count:64 Percentile:9.09(Materials Science, Multidisciplinary)

Journal Articles

Ion beam breeding of sugarcane cultivar "Ni17"

Takenoshita, Yoshihisa*; Tojima, Futoshi*; Nishi, Hiroyuki*; Shirao, Tsukasa*; Nagatani, Takeshi*; Oe, Masakazu*; Hase, Yoshihiro; Narumi, Issei

JAEA-Review 2008-055, JAEA Takasaki Annual Report 2007, P. 66, 2008/11

no abstracts in English

Journal Articles

Hydraulic modelling of unsaturated zones around three openings at the argillaceous Tournemire site (France)

Uehara, Shinichi*; Kobayashi, Akira*; Chijimatsu, Masakazu*; Onishi, Yuzo*; Fujita, Tomo; Rejeb, A.*

Proceedings of 3rd International Conference on Coupled T-H-M-C Processes in Geo-systems; Fundamentals, Modeling, Experiments and Applications (GeoProc 2008), p.419 - 425, 2008/06

Journal Articles

Development of stress conditions around a tunnel excavated in argillaceous rock related to change of saturation conditions

Uehara, Shinichi*; Kobayashi, Akira*; Chijimatsu, Masakazu*; Onishi, Yuzo*; Fujita, Tomo

Proceedings of 2nd International Conference on Coupled T-H-M-C Processes in Geo-systems; Fundamentals, Modeling, Experiments and Applications (GeoProc 2006), p.738 - 743, 2006/05

This paper reports the results of calculations about coupled hydro-mechanical process in the domain around excavations at clay rock site at Tournemire, France. We operated the numerical modelling by using a Finite Element Method code named THAMES, on the assumption that swelling pressure is parallel to saturation ratio. The results of modelling indicated that saturation ratio changes seasonally at the domain within several tens cm from tunnel wall. This extension is similar to that of damage zone observed in the tunnel at Tournemire site in 1881, which supports the idea that the saturation-desaturation cycles has decreased the rock strength and caused damage zone extension. The modelling results also suggested that the consideration of swelling pressure could affect evolution of stress state abruptly.

Journal Articles

Thermal neutron spin-echo studies on dynamics of a glass-forming polymer in a high ${it Q}$ range

Kanaya, Toshiji*; Kakurai, Kazuhisa; Tsukushi, Itaru*; Inoue, Rintaro*; Watanabe, Hiroshi*; Nishi, Masakazu*; Nakajima, Kenji; Takemura, Kazuhiro*; Furuya, Hidemine*

Journal of the Physical Society of Japan, 74(12), p.3236 - 3240, 2005/12

 Times Cited Count:5 Percentile:61.35(Physics, Multidisciplinary)

We performed thermal neutron spin echo measurements on a glass-forming polymer, deuterated polybutadiene (-[CD$$_{2}$$-CD=CD-CD$$_{2}$$]$$_{n}$$-; PB-d$$_{6}$$), in a high ${it Q}$ range up to 3.5$AA $^{-1}$$ covering the first and second peaks of the structure factor S(${it Q}$), and evaluated the decay rate $$Gamma$$(${it Q}$) of the coherent intermediate scattering function as a function of ${it Q}$. In contrast to the previous experimental findings on the first peak of S(${it Q}$) at ${it Q}$ = 1.5$AA $^{-1}$$, no "de Gennes" type narrowing was observed on the second peak at ${it Q}$ = 2.9$AA $^{-1}$$. This novel finding indicates that the narrowing is hidden by the distinct motions of the soft -CD$$_{2}$$-CD$$_{2}$$- and =CD-CD$$_{2}$$- units and the self-motions of the rigid and soft units in the ${it Q}$ range around the second peak.

Journal Articles

Neutron scattering investigation on quantum spin system SrCu$$_{2}$$(BO$$_{3}$$)$$_{2}$$

Kakurai, Kazuhisa; Nukui, Katsuyuki*; Aso, Naofumi*; Nishi, Masakazu*; Kadowaki, Hiroaki*; Kageyama, Hiroshi*; Ueda, Yutaka*; Regnault, L.-P.*; C$'e$pas, O.*

Progress of Theoretical Physics Supplement, (159), p.22 - 32, 2005/10

no abstracts in English

Journal Articles

High energy-resolution inelastic neutron scattering experiments on triplet bound state excitations in SrCu$$_{2}$$(BO$$_{3}$$)$$_{2}$$

Aso, Naofumi*; Kageyama, Hiroshi*; Nukui, Katsuyuki*; Nishi, Masakazu*; Kadowaki, Hiroaki*; Ueda, Yutaka*; Kakurai, Kazuhisa

Journal of the Physical Society of Japan, 74(8), p.2189 - 2192, 2005/08

 Times Cited Count:6 Percentile:56.93(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Highly polarized electrons from GaAs-GaAsP and InGaAs-AlGaAs strained-layer superlattice photocathodes

Nishitani, Tomohiro; Nakanishi, Tsutomu*; Yamamoto, Masahiro*; Okumi, Shoji*; Furuta, Fumio*; Miyamoto, Masaharu*; Kuwahara, Makoto*; Yamamoto, Naoto*; Naniwa, Kenichi*; Watanabe, Osamu*; et al.

Journal of Applied Physics, 97(9), p.094907_1 - 094907_6, 2005/05

 Times Cited Count:57 Percentile:13.08(Physics, Applied)

no abstracts in English

Journal Articles

THM Simulation of the Full-Scale In-Situ Engineered Barrier System Experiment in Grimsel Test Site in Switzerland

Sugita, Yutaka; Chijimatsu, Masakazu*; Ito, Akira; Kurikami, Hiroshi; Kobayashi, Akira*; Onishi, Yuzo*

P.102-107, p.102 - 107, 2003/00


Journal Articles

Effect of coupling behavior of the near fild on groundwater flow of the far field for geological disposal of high level radioactive waste

Kurikami, Hiroshi; Kobayashi, Akira*; Chijimatsu, Masakazu*; Sugita, Yutaka; Onishi, Yuzo*

Proceedings of International Conference on Coupled T-H-M-C Processes in Geo-systems; Fundamentals, Modelling, Experiments and Applications (GeoProc 2003), p.403 - 408, 2003/00

It is very important in performance assessment to estimate the impact of constructing high-level radioactive waste repositories deep underground on the regional groundwater flow system. This paper proposes a method of estimating the impact of coupled t

Journal Articles

Anomalous spin density distribution in CeB$$_{6}$$

Saito, Masahiro*; Okada, Noriko*; Nishibori, Eiji*; Takagiwa, Hiroyuki*; Yokoo, Tetsuya*; Nishi, Masakazu*; Kakurai, Kazuhisa; Kunii, Satoru*; Takata, Masaki*; Sakata, Makoto*; et al.

Journal of the Physical Society of Japan, 71(10), p.2369 - 2372, 2002/10

 Times Cited Count:12 Percentile:39.73(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Development of electrochemical hydrogen pump under vacuum condition for a compact tritium gas cycling system

Kato, Mineo; Ito, Takeshi*; Sugai, Hiroyuki; Kawamura, Yoshinori; Hayashi, Takumi; Nishi, Masataka; Tanase, Masakazu; Matsuzaki, Teiichiro*; Ishida, Katsuhiko*; Nagamine, Kanetada*

Fusion Science and Technology, 41(3), p.859 - 862, 2002/05

JAERI has a plane to develop a compact tritium gas recycling system for fusion research. This system is also very attractive for the muon-catalyzed fusion ($$mu$$CF) research at RIKEN-RAL Muon Facility in UK. For the research, JAERI has produced high purity tritium gas of 1,500 Ci and transported it to the Facility. In the $$mu$$CF experiments, the tritium gas was diluted by the deuterium in an optional concentration and the used tritium gas was carried back by the tritium transport container developed to JAERI. If it is possible to recycle the diluted tritium gas, i.e., the used tritium gas is enriched in the experimental site, the $$mu$$CF experiments should be conducted efficiently. rom the above point of view, in this paper, we propose the compact tritium gas recycling system based on the gas chromatography that has already developed in JAERI and a proton conductor.

Journal Articles

Dzyaloshinski-Moriya interaction in the 2D spin gas system SrCu$$_{2}$$(BO$$_{3}$$)$$_{2}$$

C$'e$pas, O.*; Kakurai, Kazuhisa; Regnault, L. P.*; Ziman, T.*; Boucher, J. P.*; Aso, Naofumi*; Nishi, Masakazu*; Kageyama, Hiroshi*; Ueda, Yutaka*

Physical Review Letters, 87(16), p.167205_1 - 167205_4, 2001/10

 Times Cited Count:98 Percentile:7.47(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Partially disordered antiferromagnetic phase in Ca$$_{3}$$CoRhO$$_{6}$$

Niitaka, Seiji*; Yoshimura, Kazuyoshi*; Kosuge, K.*; Nishi, Masakazu*; Kakurai, Kazuhisa

Physical Review Letters, 87(17), p.177202_1 - 177202_4, 2001/10

 Times Cited Count:89 Percentile:8.37(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Hydro-mechanical response of a fractured granitic rock mass to excavation of a test pit-the Kamaishi mine experiment in Japan

Sugita, Yutaka; Nguyen, T. S.*; B$"o$rgesson, L.*; Chijimatsu, Masakazu*; Rutqvist, J.*; Fujita, Tomo; Hernelind, J.*; Kobayashi, Akira*; Onishi, Yuzo*; Tanaka, Makoto*; et al.

International Journal of Rock Mechanics and Mining Sciences, 38(1), p.79 - 94, 2001/00


Journal Articles

Incommensurate magnetic ordering and spin-liquid-like state in a triangular lattice BaVS$$_{3}$$; Neutron diffraction and scattering study

Nakamura, Hiroyuki*; Yamasaki, Tomoaki*; Giri, S.*; Imai, Hideto*; Shiga, Masayuki*; Kojima, Kenji*; Nishi, Masakazu*; Kakurai, Kazuhisa*; Metoki, Naoto

Journal of the Physical Society of Japan, 69(9), p.2763 - 2766, 2000/09

 Times Cited Count:58 Percentile:12.79(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Ground-state magnetic structure of CeRh$$_{2}$$Si$$_{2}$$ and response to hydrostatic pressure as studied by neutron diffraction

Kawarazaki, Shuzo*; Sato, Masugu*; Miyako, Yoshihito*; Chigusa, Nobusato*; Watanabe, Kenji*; Metoki, Naoto; Koike, Yoshihiro; Nishi, Masakazu*

Physical Review B, 61(6), p.4167 - 4173, 2000/02

 Times Cited Count:83 Percentile:5.98(Materials Science, Multidisciplinary)

no abstracts in English

JAEA Reports

Coupled Thermo-Hydro-Mechanical Experiment at Kamaishi Mine Technical Note 16-99-03, Analyses of Task 2C, DECOVALEXII

Chijimatsu, Masakazu*; Fujita, Tomo; Kobayashi, Akira*; Onishi, Yuzo*

JNC-TN8400 99-031, 61 Pages, 1999/06


It is an important part of the near field performance assessment of nuclear waste disposal to evaluate couples thermo-hydro-mechanical (T-H-M) phenomena, e.g., thermal effects on groundwater flow through rock matrix and water seepage into the buffer material, the generation of swelling pressure of the buffer material, and thermal stresses potentially affecting porosity and fracture apertures of the rock. An in-situ T-H-M experiment naned 'Engineered Barrier Experiment' has been oonducted at the Kamaishi Mine, of which host rock is granodiorite, in order to establish conceptual models of the coupled T-H-M processes and to build confidence in mathematical models and computer codes. The coupled T-H-M experiment is one of tasks in DECOVALEX (DEvelopment of COupled models and their VALidation against EXperiments) project which is an international co-operative project and it is defined as Task 2. The Task 2 for the DECOVALEX project are divided into three subtasks (A-C) in accordance with the programme and availability of data, called subtasks. This note describes the results of subtask C. Subtask C is a coupled thermo-hydro-mechanical analysis in the near field.

Journal Articles

Spin gap in the hole-doped spin ladder system (Sr$$_{2.5}$$Ca$$_{11.5}$$)Cu$$_{24}$$O$$_{41}$$; Neutron inelastic scattering study

Katano, Susumu; *; Akimitsu, Jun*; Nishi, Masakazu*; Kakurai, Kazuhisa*

Physical Review Letters, 82(3), p.636 - 639, 1999/01

 Times Cited Count:63 Percentile:10.77(Physics, Multidisciplinary)

no abstracts in English

39 (Records 1-20 displayed on this page)