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Journal Articles

Breakdown of linear spin-wave theory and existence of spinon bound states in the frustrated kagome-lattice antiferromagnet

Mattan, K.*; Ono, Toshio*; Kawamura, Seiko; Nakajima, Kenji; Nambu, Yusuke*; Sato, Taku*

Physical Review B, 105(13), p.134403_1 - 134403_8, 2022/04

 Times Cited Count:1 Percentile:37.1(Materials Science, Multidisciplinary)

Spin dynamics of the spin-1/2 kagome-lattice antiferromagnet Cs$$_{2}$$Cu$$_{3}$$SnF$$_{12}$$ was studied using high-resolution, time-of-flight inelastic neutron scattering. The flat mode, a characteristic of the frustrated kagome antiferromagnet, and the low-energy dispersive mode, which is dominated by magnons, can be well described by the linear spin-wave theory. However, the theory fails to describe three weakly dispersive modes between 9 and 14 meV. These modes could be attributed to two-spinon bound states, which decay into free spinons away from the zone center and at a high temperature, giving rise to continuum scattering.

Journal Articles

Recent progress in the energy recovery linac project in Japan

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.

Journal Articles

Recent progress of construction for compact Energy Recover Linac

Kobayashi, Yukinori*; Sakanaka, Shogo*; Sato, Kotaro*; Kasuga, Toshio*; Kawata, Hiroshi*; Hajima, Ryoichi; Nakamura, Norio*

Proceedings of 6th Annual Meeting of Particle Accelerator Society of Japan (CD-ROM), p.66 - 69, 2009/08

Future synchrotron light source based on the Energy Recovery Linac (ERL) is expected to be capable of producing super-brilliant and/or ultra-short pulses of synchrotron radiation with a potential of the oscillating type for X-ray free electron laser. We are constructing the R&D machine which is called the compact ERL including the developments of an ultra-low emittance electron gun and superconducting cavities for both the injector and the main linacs under the collaboration between KEK, JAEA, ISSP, and other institutes. In this paper, we report recent progress of the construction for the compact ERL with a repair of a KEK east counter hall.

JAEA Reports

Detaching test on an irradiated mock-up contaminated with tritium from the core of JMTR

Tomita, Kenji; Tsuchiya, Kunihiko; Onuma, Yuichi; Inoue, Shuichi; Watanabe, Hiroyuki; Saito, Takashi; Kikuchi, Taiji; Hayashi, Kimio; Kitajima, Toshio

JAEA-Technology 2008-036, 61 Pages, 2008/06

JAEA-Technology-2008-036.pdf:7.47MB

The second in-situ irradiation experiment using a mock-up (ORIENT-II, JMTR capsule Number: 99M-54J) with a tritium breeder (Li$$_{2}$$TiO$$_{3}$$) pebble bed in the Japan Materials Testing Reactor (JMTR) was finished on Aug. 1, 2006. Consideration on the detaching procedure of the irradiated mock-up contaminated with tritium with pebble bed and a detaching test of this mock-up was carried out. The tritium removal properties were examined in the irradiated mock-up, the sweep gas tube, the protective tube and the junction box, for the decreasing of the tritium release to the area of detaching test. Melting/enclosed tests of sealing plug were also carried out for the prevention of tritium leakage from sweep gas lines of pebble bed. Then, the detaching test of the pebble bed was carried out. This report describes the results of tritium removal tests, examination of the detaching procedure, and the detaching test, as well as knowledge obtained from these tests and works.

JAEA Reports

Conceptual study of $$^{99}$$Mo production facility in JMTR

Iimura, Koichi; Hosokawa, Jinsaku; Kanno, Masaru; Kitajima, Toshio; Nakagawa, Tetsuya; Sakamoto, Taichi; Hori, Naohiko; Kawamura, Hiroshi

JAEA-Technology 2008-035, 47 Pages, 2008/06

JAEA-Technology-2008-035.pdf:7.91MB

At Oarai Research and Development Center, Japan Atomic Energy Agency (JAEA) advances the plan of refurbishing Japan Materials Testing Reactor (JMTR) to start the operation in fiscal 2011. As part of effective use for JMTR, JAEA is planning to product $$^{99}$$Mo, which is a parent nuclide of $$^{rm 99m}$$Tc. $$^{rm 99m}$$Tc is most commonly used as a radiopharmaceutical in the field of nuclear medicine. Currently the supplying of $$^{99}$$Mo is only depend on imports from foreign countries, so JAEA is aiming at domestic production of a part of $$^{99}$$Mo in cooperation with the industrial circles. In this article, JAEA described the process, the choice and fabric of the irradiation facilities for $$^{99}$$Mo production, the technical study of commercializing equipment after irradiation, and the cost study for $$^{99}$$Mo production.

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.

JAEA Reports

Investigation and design of the dismantling process of irradiation capsules containing tritium, 1; Conceptual investigation and basic design

Hayashi, Kimio; Nakagawa, Tetsuya; Onose, Shoji; Ishida, Takuya; Kodaka, Hideo; Katsuyama, Kozo; Kitajima, Toshio; Takahashi, Kozo; Tsuchiya, Kunihiko; Nakamichi, Masaru; et al.

JAEA-Technology 2008-010, 68 Pages, 2008/03

JAEA-Technology-2008-010.pdf:11.31MB

In-pile functional tests of breeding blankets for fusion reactors have been planned by Japan Atomic Energy Agency (JAEA), using a test blanket module (TBM) which will be loaded in ITER. The present report describes a conceptual investigation and a basic design of the dismantling process for irradiation capsules which were used in irradiation experiments by the Japan Materials Testing Reactor (JMTR) of JAEA. In the present design, the irradiation capsule is cut by a band saw; the released tritium is recovered safely by a purge-gas system, and is consolidated into a radioactive waste form. Furthermore, adoption of the inner-box enclosing the dismantling apparatus has brought a prospect to be able to utilize an existing hot cell (beta-$$gamma$$ cell) equipped with usual wall material permeable to tritium, without extensive refurbishing of the cell. Thus, the present study has indicated the feasibility of the present dismantling process for the irradiated JMTR capsules containing tritium.

Journal Articles

Status of R&D efforts toward the ERL-based light source

Sakanaka, Shogo*; Kobayashi, Yukinori*; Sato, Kotaro*; Kasuga, Toshio*; Kawata, Hiroshi*; Hajima, Ryoichi; Nakamura, Norio*

Proceedings of 5th Annual Meeting of Particle Accelerator Society of Japan and 33rd Linear Accelerator Meeting in Japan (CD-ROM), p.225 - 227, 2008/00

Collaborative research efforts towards future ERL-based light sources are carried out. We present the R&D status of an electron gun and superconducting cavities, updated design study on the test facility (Compact ERL).

Journal Articles

Heavy-ion induced current through an oxide layer

Takahashi, Yoshihiro*; Oki, Takahiro*; Nagasawa, Takaharu*; Nakajima, Yasuhito*; Kawanabe, Ryu*; Onishi, Kazunori*; Hirao, Toshio; Onoda, Shinobu; Mishima, Kenta; Kawano, Katsuyasu*; et al.

Nuclear Instruments and Methods in Physics Research B, 260(1), p.309 - 313, 2007/07

 Times Cited Count:4 Percentile:35.75(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Development of hydraulic analysis code for optimizing thermo-chemical IS process reactors

Terada, Atsuhiko; Hino, Ryutaro; Hirayama, Toshio; Nakajima, Norihiro; Sugiyama, Hitoshi*

Proceedings of 15th International Conference on Nuclear Engineering (ICONE-15) (CD-ROM), 6 Pages, 2007/04

The Japan Atomic Energy Agency has been conducting study on thermochemical IS process for water splitting hydrogen production. Based on the test results and know-how obtained through the bench-scale test, a pilot test plant, which has a hydrogen production performance of 30 Nm$$^{3}$$/h, is being designed conceptually as the next step of the IS process development. In design of the IS pilot plant, it is important to make chemical reactors compact with high performance from the viewpoint of plant cost reduction. A new hydraulic analytical code has been developed for optimizing mixing performance of multi-phase flow involving chemical reactions especially in the Bunsen reactor. Preliminary analytical results obtained with above mentioned code, especially flow patterns induced by swirling flow agreed well with that measured by water experiments, which showed vortex breakdown pattern in a simplified Bunsen reactor.

Journal Articles

Deployment of computational science in JAEA

Nakajima, Norihiro; Araya, Fumimasa; Hirayama, Toshio

Genshiryoku eye, 52(10), p.22 - 34, 2006/10

no abstracts in English

Journal Articles

Research and development of grid computing in Japan Atomic Energy Agency

Suzuki, Yoshio; Aoyagi, Tetsuo; Tani, Masayuki; Nakajima, Norihiro; Hirayama, Toshio

Genshiryoku eye, 52(10), p.35 - 39, 2006/10

no abstracts in English

Journal Articles

Optimization for SEU/SET immunity on 0.15 $$mu$$m fully depleted CMOS/SOI digital logic devices

Makihara, Akiko*; Asai, Hiroaki*; Tsuchiya, Yoshihisa*; Amano, Yukio*; Midorikawa, Masahiko*; Shindo, Hiroyuki*; Kuboyama, Satoshi*; Onoda, Shinobu; Hirao, Toshio; Nakajima, Yasuhito*; et al.

Proceedings of 7th International Workshop on Radiation Effects on Semiconductor Devices for Space Application (RASEDA-7), p.95 - 98, 2006/10

no abstracts in English

JAEA Reports

Examination on detaching method of an irradiated mock-up with Li$$_{2}$$TiO$$_{3}$$ pebble bed from the core of JMTR

Ikeshima, Yoshiaki; Ishida, Takuya*; Tsuchiya, Kunihiko; Tomita, Kenji; Ebisawa, Hiroyuki; Magome, Hirokatsu; Nakamichi, Masaru*; Kitajima, Toshio; Kawamura, Hiroshi

JAERI-Tech 2005-005, 37 Pages, 2005/02

JAERI-Tech-2005-005.pdf:7.59MB

no abstracts in English

Journal Articles

Development of a meta-computing infrastructure for parallel coupled simulations

Hazama, Osamu; Nakajima, Norihiro; Hirayama, Toshio; Post, P.*; Wolf, K.*

IWACOM, P. 161, 2004/11

The numerical methods and computational hardware of today allow for studies on multi-disciplinary simulations. We have been developing an "integrated numerical simulation system" to solve coupled simulation problems under meta-computing environments. The system aims to construct a competent coupler for carrying out multi-disciplinary simulations by allowing concurrent execution of arbitrary simulation codes on different computers in parallel. The effectiveness of this system infrastructure is illustrated through its applications to fluid-structure interactive problems.

Journal Articles

Towards to realize a quake-proof information control and management system for nuclear power plant

Nakajima, Norihiro; Kimura, Hideo; Higuchi, Kenji; Aoyagi, Tetsuo; Suzuki, Yoshio; Hirayama, Toshio; Yagawa, Genki

Dai-23-Kai Nihon Shimyureshon Gakkai Taikai Happyo Rombunshu, p.117 - 120, 2004/06

The pablic acceptance of nuclear power plants operations requests information of status for the safety and ease. Previous technology in computational scinece is generarlly carried out the analysis as an uniform structure, although the plants are assembled by thousand of parts. The proposed approach is to develope assembled structural analysis and fluid/heat analyis in assembled structures under the natural and actual environmnet such as daily operation, small quakeing which does not induce shut down procedure, and so on.

Journal Articles

Magnetization plateaux of the ${it S}$=1/2 two-dimensional frustrated antiferromagnet Cs$$_{2}$$CuBr$$_{4}$$

Ono, Toshio*; Tanaka, Hidekazu*; Kolomiyets, O.*; Mitamura, Hiroyuki*; Goto, Tsuneaki*; Nakajima, Kenji; Osawa, Akira; Koike, Yoshihiro; Kakurai, Kazuhisa; Klenke, J.*; et al.

Journal of Physics; Condensed Matter, 16(11), p.S773 - S778, 2004/03

 Times Cited Count:64 Percentile:89.42(Physics, Condensed Matter)

no abstracts in English

JAEA Reports

The Recovery from water leakage accident in JMTR

Ito, Haruhiko; Homma, Kenzo; Itabashi, Yukio; Tabata, Toshio; Akashi, Kazutomo; Inaba, Yukio; Kumahara, Hajime; Takahashi, Kunihiro; Kitajima, Toshio; Yokouchi, Iichiro

JAERI-Review 2003-024, 76 Pages, 2003/10

JAERI-Review-2003-024.pdf:8.35MB

no abstracts in English

Journal Articles

Development of new technique for temperature control of irradioation capsules

Kanno, Masaru; Kitajima, Toshio; Homma, Kenzo

KAERI/GP-195/2002, p.71 - 75, 2002/00

Recent irradiation studies aiming at clarifying the detailed mechanisms of irradiation damages to the reactor materials require to maintain the specimens at constant temperature regardless of the reactor power level,in order to avoid artificial effects of temperature transient due to reactor power change. In order to deal with this problem, JMTR has adopted feed-foward control to the gas pressure based on the reactor power signal, and developed new temperature control technique in combination with feedback control of heater power.

Journal Articles

Numerical analysis on ingress of coolant event in vacuum vessel using modified TRAC-BF1

Kurihara, Ryoichi; Ajima, Toshio*; Ueda, Shuzo; Seki, Yasushi

Journal of Nuclear Science and Technology, 38(7), p.571 - 576, 2001/07

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

no abstracts in English

52 (Records 1-20 displayed on this page)