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Journal Articles

Cryogenic sample environments shared at the MLF, J-PARC

Kawamura, Seiko; Takahashi, Ryuta*; Ishikado, Motoyuki*; Yamauchi, Yasuhiro*; Nakamura, Masatoshi*; Ouchi, Keiichi*; Kira, Hiroshi*; Kambara, Wataru*; Aoyama, Kazuhiro*; Sakaguchi, Yoshifumi*; et al.

Journal of Neutron Research, 21(1-2), p.17 - 22, 2019/05

The Cryogenics and Magnets group in the Sample Environment team is responsible for operation of cryostats and magnets for user's experiments at the MLF in J-PARC. We have introduced a top-loading $$^4$$He cryostat, a bottom-loading $$^3$$He cryostat, a dilution refrigerator insert and a superconducting magnet. The frequency of use of them dramatically becomes higher in these two years, as the beam power and the number of proposal increase. To respond such situation, we have made efforts to enhance performance of these equipment as follows. The $$^3$$He cryostat originally involves an operation software for automatic initial cooling down to the base temperature and automatic re-charge of $$^3$$He. Recently we made an additional program for automatic temperature control with only the sorb heater. Last year, a new outer vacuum chamber of the magnet with an oscillating radial collimator (ORC) was fabricated. The data quality was drastically improved by introducing this ORC so that the magnet can be used even for the inelastic neutron scattering experiments.

Journal Articles

Study on use of superconducting magnet and first inelastic neutron scattering experiment under magnetic field at 4SEASONS spectrometer

Kajimoto, Ryoichi; Ishikado, Motoyuki*; Kira, Hiroshi*; Kaneko, Koji; Nakamura, Mitsutaka; Kamazawa, Kazuya*; Inamura, Yasuhiro; Ikeuchi, Kazuhiko*; Iida, Kazuki*; Murai, Naoki; et al.

Physica B; Condensed Matter, 556, p.26 - 30, 2019/03

 Times Cited Count:2 Percentile:17.06(Physics, Condensed Matter)

Journal Articles

Molecular dynamics simulations of physical properties of water and cations in montmorillonite interlayer; Application to diffusion model

Yotsuji, Kenji*; Tachi, Yukio; Kawamura, Katsuyuki*; Arima, Tatsumi*; Sakuma, Hiroshi*

Nendo Kagaku, 58(1), p.8 - 25, 2019/00

Molecular dynamics (MD) simulations were conducted to investigate physical properties of water and cations in montmorillonite interlayer nanopores. The swelling behaviors and hydration states were firstly evaluated as functions of interlayer cations and layer charge. The diffusion coefficients of water and cations in interlayer nanopores were decreased in comparison with those in bulk water and came closer to those in bulk water when basal spacing increased. The viscosity coefficients of interlayer water estimated indicated a significant effect of viscoelectricity at 1- and 2-layer hydration states and higher layer charge of montmorillonite. These trends from MD calculations were confirmed to be consistent with existing measured data and previous MD simulation. In addition, model and parameter related to viscoelectric effect used in the diffusion model was refined based on comparative discussion between MD simulations and measurements. The series of MD calculations could provide atomic level understanding for the developments and improvements of the diffusion model for compacted montmorillonite.

Journal Articles

Status report of the chopper spectrometer 4SEASONS

Kajimoto, Ryoichi; Nakamura, Mitsutaka; Inamura, Yasuhiro; Kamazawa, Kazuya*; Ikeuchi, Kazuhiko*; Iida, Kazuki*; Ishikado, Motoyuki*; Murai, Naoki; Kira, Hiroshi*; Nakatani, Takeshi; et al.

Journal of Physics; Conference Series, 1021(1), p.012030_1 - 012030_6, 2018/06

Journal Articles

Continuum excitation and pseudospin wave in quantum spin-liquid and quadrupole ordered states of Tb$$_{2+x}$$Ti$$_{2-x}$$O$$_{7+y}$$

Kadowaki, Hiroaki*; Wakita, Mika*; F${aa}$k, B.*; Ollivier, J.*; Kawamura, Seiko; Nakajima, Kenji; Takatsu, Hiroshi*; Tamai, Mototake*

Journal of the Physical Society of Japan, 87(6), p.064704_1 - 064704_6, 2018/06

 Times Cited Count:4 Percentile:14.47(Physics, Multidisciplinary)

The ground states of the frustrated pyrochlore oxide Tb$$_{2+x}$$Ti$$_{2-x}$$O$$_{7+y}$$ have been studied by inelastic neutron scattering experiments. Three single-crystal samples are investigated; one shows no phase transition ($$x = -0.007 < x_{c} < sim -0.0025$$), being a putative quantum spin-liquid (QSL), and the other two ($$x = 0.000, 0.003$$) show electric quadrupole ordering (QO) below $$T_{c} sim 0.5$$ K. The QSL sample shows continuum excitation spectra with an energy scale 0.1 meV as well as energy-resolution-limited (nominally) elastic scattering. As $$x$$ is increased, pseudospin wave of the QO state emerges from this continuum excitation, which agrees with that of powder samples and consequently verifies good $$x$$ control for the present single crystal samples.

Journal Articles

Sample environment at the J-PARC MLF

Kawamura, Seiko; Oku, Takayuki; Watanabe, Masao; Takahashi, Ryuta; Munakata, Koji*; Takata, Shinichi; Sakaguchi, Yoshifumi*; Ishikado, Motoyuki*; Ouchi, Keiichi*; Hattori, Takanori; et al.

Journal of Neutron Research, 19(1-2), p.15 - 22, 2017/11

Sample environment (SE) team at the Materials and Life Science Experimental Facility (MLF) in J-PARC has worked on development and operation of SE equipment and devices. All the members belong to one sub-team at least, such as Cryogenic and magnet, High temperature, High pressure, Soft matter and special environment including Pulse magnet, Hydrogen environment, Light irradiation and $$^3$$He spin filter. Cryostats, a magnet, furnaces, a VX-6-type Paris-Edinburgh press and a prototype of a Spin-Exchange Optical Pumping (SEOP) based $$^3$$He spin filter for polarized neutron beam experiments are in operation. Furthermore, a prototype of compact power supply for a pulsed magnet system is currently developed. In the J-PARC Research Building, several pieces of equipment for softmatter research such as a rheometer and a gas and vapor adsorption measurement instrument have been prepared.

Journal Articles

Materials and Life Science Experimental Facility at the Japan Proton Accelerator Research Complex, 3; Neutron devices and computational and sample environments

Sakasai, Kaoru; Sato, Setsuo*; Seya, Tomohiro*; Nakamura, Tatsuya; To, Kentaro; Yamagishi, Hideshi*; Soyama, Kazuhiko; Yamazaki, Dai; Maruyama, Ryuji; Oku, Takayuki; et al.

Quantum Beam Science (Internet), 1(2), p.10_1 - 10_35, 2017/09

Neutron devices such as neutron detectors, optical devices including supermirror devices and $$^{3}$$He neutron spin filters, and choppers are successfully developed and installed at the Materials Life Science Facility (MLF) of the Japan Proton Accelerator Research Complex (J-PARC), Tokai, Japan. Four software components of MLF computational environment, instrument control, data acquisition, data analysis, and a database, have been developed and equipped at MLF. MLF also provides a wide variety of sample environment options including high and low temperatures, high magnetic fields, and high pressures. This paper describes the current status of neutron devices, computational and sample environments at MLF.

Journal Articles

Stability of montmorillonite edge faces studied using first-principles calculations

Sakuma, Hiroshi*; Tachi, Yukio; Yotsuji, Kenji; Suehara, Shigeru*; Arima, Tatsumi*; Fujii, Naoki*; Kawamura, Katsuyuki*; Honda, Akira

Clays and Clay Minerals, 65(4), p.252 - 272, 2017/08

 Percentile:100(Chemistry, Physical)

Structure and stability of montmorillonite edge faces (110), (010), (100), and (130) of the layer charges y = 0.5 and 0.33 are investigated by the first-principles electronic calculations based on the density functional theory. Stacking and single layer models are tested for understanding the effect of stacking on the stability of montmorillonite edge faces. Most stacking layers stabilize the edge faces by making hydrogen bonds between the layers; therefore, the surface energy of stacking layers is reduced rather than the single layer model. This indicates that the surface energy of edge faces should be estimated depending on the swelling conditions. Lowest surface energies of (010) and (130) edge faces were realized by the presence of Mg ions on the edge faces. These edge faces have a strong adsorption site for cations due to local negative charge of the edges.

Journal Articles

Algebraic design of multi-dimensional transfer function using transfer function synthesizer

Kawamura, Takuma; Idomura, Yasuhiro; Miyamura, Hiroko; Takemiya, Hiroshi

Journal of Visualization, 20(1), p.151 - 162, 2017/02

 Times Cited Count:1 Percentile:75.54(Computer Science, Interdisciplinary Applications)

In this paper, we propose a novel transfer function design interface for multivariate volume rendering. In the conventional multivariate volume rendering, GUI based transfer function design interfaces were limited to two-dimensional variables space. In order to design higher dimensional transfer functions in an interactive and intuitive manner, a Transfer Function Synthesizer (TFS) is developed. On the TFS, multi-dimensional transfer functions are generated by algebraic synthesis of one-dimensional transfer functions, which are designed based on the conventional GUIs or algebraic expressions. The TFS enables not only multivariate volume rendering but also general visualization techniques such as surface visualization and image composition within the framework of volume rendering. The TFS is implemented on the remote visualization system PBVR, and applied to various multivariate scalar volume data generated from nuclear applications.

Journal Articles

Inelastic and quasi-elastic neutron scattering spectrometers in J-PARC

Seto, Hideki; Ito, Shinichi; Yokoo, Tetsuya*; Endo, Hitoshi*; Nakajima, Kenji; Shibata, Kaoru; Kajimoto, Ryoichi; Kawamura, Seiko; Nakamura, Mitsutaka; Kawakita, Yukinobu; et al.

Biochimica et Biophysica Acta; General Subjects, 1861(1), p.3651 - 3660, 2017/01

 Times Cited Count:12 Percentile:10.37(Biochemistry & Molecular Biology)

J-PARC, Japan Proton Accelerator Research Complex provides short pulse proton beam at a repetition rate 25 Hz and the maximum power is expected to be 1 MW. Materials and Life Science Experimental Facility (MLF) has 23 neutron beam ports and 21 instruments have already been operated or under construction / commissioning. There are 6 inelastic / quasi-elastic neutron scattering spectrometers and the complementary use of these spectrometers will open new insight for life science.

Journal Articles

Spontaneous decays of magneto-elastic excitations in non-collinear antiferromagnet (Y,Lu)MnO$$_{3}$$

Oh, J.*; Le, M. D.*; Nahm, H.-H.*; Sim, H.*; Jeong, J.*; Perring, T. G.*; Woo, H.*; Nakajima, Kenji; Kawamura, Seiko; Yamani, Z.*; et al.

Nature Communications (Internet), 7, p.13146_1 - 13146_6, 2016/10

 Times Cited Count:14 Percentile:14.62(Multidisciplinary Sciences)

Magnons and phonons are fundamental quasiparticles in a solid and can be coupled together to form a hybrid quasi-particle. However, detailed experimental studies on the underlying Hamiltonian of this particle are rare for actual materials. Moreover, the anharmonicity of such magnetoelastic excitations remains largely unexplored, although it is essential for a proper understanding of their diverse thermodynamic behaviour and intrinsic zero-temperature decay. Here we show that in non-collinear antiferromagnets, a strong magnon phonon coupling can significantly enhance the anharmonicity, resulting in the creation of magnetoelastic excitations and their spontaneous decay. By measuring the spin waves over the full Brillouin zone and carrying out anharmonic spin wave calculations using a Hamiltonian with an explicit magnon phonon coupling, we have identified a hybrid magnetoelastic mode in (Y,Lu)MnO$$_{3}$$ and quantified its decay rate and the exchange-striction coupling termrequired to produce it.

Journal Articles

Creation of research center related to decommissioning Fukushima Daiichi Nuclear Power Station

Kawamura, Hiroshi; Yamada, Tomonori

Kinzoku, 86(7), p.580 - 589, 2016/07

no abstracts in English

Journal Articles

Creation of research base related to remote technology for decommissioning Fukushima Daiichi Nuclear Power Station

Kawamura, Hiroshi

Haikan Gijutsu, 58(7), p.1 - 8, 2016/06

no abstracts in English

Journal Articles

Technical estimation for mass production of highly-concentrated $$^{rm 99m}$$Tc solution from $$^{99}$$Mo to be obtained by ($$n,gamma$$) reaction; A Preliminary study using inactive Re instead of $$^{rm 99m}$$Tc

Tanase, Masakazu*; Fujisaki, Saburo*; Ota, Akio*; Shiina, Takayuki*; Yamabayashi, Hisamichi*; Takeuchi, Nobuhiro*; Tsuchiya, Kunihiko; Kimura, Akihiro; Suzuki, Yoshitaka; Ishida, Takuya; et al.

Radioisotopes, 65(5), p.237 - 245, 2016/05

no abstracts in English

Journal Articles

Creation of research infrastructure for decommissioning Fukushima Daiichi Nuclear Power Plants

Kawamura, Hiroshi

Dai-24-Kai Hoshasen Riyo Sogo Shimpojiumu Shiryoshu, p.61 - 72, 2016/01

no abstracts in English

Journal Articles

Status of research base for decommissioning

Kawamura, Hiroshi

Denki Hyoron, 100(11), p.19 - 27, 2015/11

no abstracts in English

Journal Articles

Program of the analysis and research laboratory for Fukushima-Daiichi and advanced techniques to be applied in the laboratory

Sekio, Yoshihiro; Yoshimochi, Hiroshi; Kosaka, Ichiro; Hirano, Hiroyasu; Koyama, Tomozo; Kawamura, Hiroshi

Proceedings of 52nd Annual Meeting of Hot Laboratories and Remote Handling Working Group (HOTLAB 2015) (Internet), 8 Pages, 2015/09

Due to the Fukushima Daiichi Nuclear Power Plant accident in March 2011, the safe and secure implementations of the decommissioning for Fukushima Daiichi Nuclear Power Plant has been positioned as the urgent tasks in Japan. Japan Atomic Energy Agency has a critical mission of analysing radioactive wastes having generated by the accident for long-term storage and disposal methods. This will be performed in two hot laboratories to be constructed in Okuma Analysis and Research Center at Fukushima Daiichi Nuclear Power Plant site. In one laboratory, radioactive wastes such as rubbles and secondary wastes will be treated, whereas debris such as fuel debris and high dose structural materials will be handled in the other laboratory. The detail considerations for advanced techniques and experimental apparatus to be installed are underway.

Journal Articles

Industrial production with the reactor for research

Kawamura, Hiroshi

Gakujutsu No Doko, 20(6), p.32 - 38, 2015/06

no abstracts in English

Journal Articles

Industrial production with the reactor for research

Kawamura, Hiroshi

Denki Hyoron, 100(5), p.11 - 12, 2015/05

no abstracts in English

Journal Articles

Visualization technique for large-scale data by particle-based volume rendering

Kawamura, Takuma; Idomura, Yasuhiro; Miyamura, Hiroko; Imamura, Toshiyuki*; Takemiya, Hiroshi

Shisutemu Seigyo Joho Gakkai Rombunshi, 28(5), p.221 - 227, 2015/05

However remote volume visualization is important to obtain knowledge from complicated large-scale simulation results on supercomputer, the rendering speed and data transfer speed becomes bottleneck of the conventional Client/Server volume visualization techniques. Client/Server visualization system using particle-based volume rendering enables interactive volume visualization, which converts the original volume data to small size light particle data utilizing the supercomputer and transfer the data to Client PC. This system generated the particle data at a few seconds using parallel process on supercomputer Kei with strong scaling till 1000 processers.

377 (Records 1-20 displayed on this page)