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Journal Articles

Measurement of neutron scattering cross section of nano-diamond with particle diameter of approximately 5 nm in energy range of 0.2 meV to 100 meV

Teshigawara, Makoto; Tsuchikawa, Yusuke*; Ichikawa, Go*; Takata, Shinichi; Mishima, Kenji*; Harada, Masahide; Oi, Motoki; Kawamura, Yukihiko*; Kai, Tetsuya; Kawamura, Seiko; et al.

Nuclear Instruments and Methods in Physics Research A, 929, p.113 - 120, 2019/06

 Times Cited Count:4 Percentile:20.8(Instruments & Instrumentation)

A nano-diamond is an attractive neutron reflection material below cold neutron energy. The total neutron cross section of a nano-diamond was derived from a neutron transmission measurement over the neutron energy range of 0.2 meV to 100 meV because total neutron cross section data were not available. The total cross section of a nano-diamond with particle size of approximately 5 nm increased with a decrease in neutron energy to 0.2 meV. It was approximately two orders of magnitude larger than that of graphite at 0.2 meV. The contribution of inelastic scattering to the total cross section was to be shown negligible small at neutron energies of 1.2, 1.5, 1.9, 2.6, and 5.9 meV in the inelastic neutron scattering measurement. Moreover, small-angle neutron scattering measurements of the nano-diamond showed a large scattering cross section in the forward direction for low neutron energies.

Journal Articles

Status of neutron spectrometers at J-PARC

Kajimoto, Ryoichi; Yokoo, Tetsuya*; Nakamura, Mitsutaka; Kawakita, Yukinobu; Matsuura, Masato*; Endo, Hitoshi*; Seto, Hideki*; Ito, Shinichi*; Nakajima, Kenji; Kawamura, Seiko

Physica B; Condensed Matter, 562, p.148 - 154, 2019/06

 Times Cited Count:3 Percentile:60.07(Physics, Condensed Matter)

Journal Articles

Fuel debris' air cooling analysis using a lattice Boltzmann method

Onodera, Naoyuki; Idomura, Yasuhiro; Kawamura, Takuma; Uesawa, Shinichiro; Yamashita, Susumu; Yoshida, Hiroyuki

Proceedings of 27th International Conference on Nuclear Engineering (ICONE-27) (Internet), 6 Pages, 2019/05

A dry method is one of practical methods for decommissioning the TEPCO's Fukushima Daiichi Nuclear Power Station. Japan Atomic Energy Agency (JAEA) has been evaluating the air cooling performance by using the JUPITER code. However, the JUPITER code requires a large computational cost to capture debris' structures. To accelerate such CFD analyses, we use the CityLBM code, which is based on the lattice Boltzmann method (LBM) and is highly optimized for GPUs. The CityLBM code is validated against free convective heat transfer experiments at JAEA, and the similar accuracy as the JUPITER code is confirmed regarding the prediction capability of heat transfer and the resulting temperature distributions. It is also shown that the elapse time of a CityLBM simulation on GPUs is reduced to 1/6 compared with that of the corresponding JUPITER simulation on CPUs with the same number of GPUs and CPUs. The results show that the LBM is promising for accelerating thermal convective simulations.

Journal Articles

Development of compact high field pulsed magnet system for new sample environment equipment at MLF in J-PARC

Watanabe, Masao; Nojiri, Hiroyuki*; Ito, Shinichi*; Kawamura, Seiko; Kihara, Takumi*; Masuda, Takatsugu*; Sahara, Takuro*; Soda, Minoru*; Takahashi, Ryuta

JPS Conference Proceedings (Internet), 25, p.011024_1 - 011024_5, 2019/03

Recently, neutron scattering experiments have been rapidly progressed under high magnetic field. In the J-PARC, proto-type compact pulse magnet system with the power supply, the coil and the sample stick has been developed. Basic specifications of the power supply are as follows; maximum charged voltage with capacitor is 2 kV, maximum current is 8 kA, repetition rate is a pulse per several minutes and pulse duration is several msec. Maximum magnetic field in the coil is more than 30 Tesla. The sample stick is designed for Orange-Cryostat. In this presentation, We report the details of the pulsed magnet system and the performance of it on neutron scattering experiments at MLF beam line (HRC).

Journal Articles

Colossal barocaloric effects in plastic crystals

Li, B.*; Kawakita, Yukinobu; Kawamura, Seiko; Sugahara, Takeshi*; Wang, H.*; Wang, J.*; Chen, Y.*; Kawaguchi, Saori*; Kawaguchi, Shogo*; Ohara, Koji*; et al.

Nature, 567(7749), p.506 - 510, 2019/03

 Times Cited Count:43 Percentile:1.03(Multidisciplinary Sciences)

Refrigeration is of vital importance for modern society for example, for food storage and air conditioning- and 25 to 30% of the world's electricity is consumed for refrigeration. Current refrigeration technology mostly involves the conventional vapour compression cycle, but the materials used in this technology are of growing environmental concern because of their large global warming potential. As a promising alternative, refrigeration technologies based on solid-state caloric effects have been attracting attention in recent decades. However, their application is restricted by the limited performance of current caloric materials, owing to small isothermal entropy changes and large driving magnetic fields. Here we report colossal barocaloric effects (CBCEs) (barocaloric effects are cooling effects of pressure-induced phase transitions) in a class of disordered solids called plastic crystals. The obtained entropy changes in a representative plastic crystal, neopentylglycol, are about 389 joules per kilogram per kelvin near room temperature. Pressure-dependent neutron scattering measurements reveal that CBCEs in plastic crystals can be attributed to the combination of extensive molecular orientational disorder, giant compressibility and highly anharmonic lattice dynamics of these materials. Our study establishes the microscopic mechanism of CBCEs in plastic crystals and paves the way to next-generation solid-state refrigeration technologies.

Journal Articles

Fast reactor core seismic experiment and analysis under strong excitation

Yamamoto, Tomohiko; Iwasaki, Akihisa*; Kawamura, Kazuki*; Matsubara, Shinichiro*; Harada, Hidenori*

Proceedings of 2018 ASME Pressure Vessels and Piping Conference (PVP 2018), 8 Pages, 2018/07

To design fast reactor (FR) core components, seismic response must be evaluated in order to ensure structural integrity. Thus, a core seismic analysis method has been developed to evaluate 3D core vibration behavior considering fluid structure interaction and vertical displacements (rising). 1/1.5 scale 37 core element mock-ups hexagonal-matrix experiment was performed to validate the core elements vibration analysis code in three dimensions (REVIAN-3D). Based on the test data, the analysis model newly incorporated to respond to strong excitation was verified.

JAEA Reports

Proceedings of the MLF User Group Meeting on Direct Geometry Spectrometers (DIRECTION 2017); October 16-17, 2017, Ibaraki Quantum Beam Research Center (Tokai, Ibaraki, Japan)

Kajimoto, Ryoichi; Yokoo, Tetsuya*; Kamazawa, Kazuya*; Nakamura, Mitsutaka; Kawamura, Seiko; Ito, Shinichi*; Nakajima, Kenji

JAEA-Review 2017-031, 107 Pages, 2018/02

JAEA-Review-2017-031.pdf:17.43MB

The joint user meeting for four direct-geometry neutron spectrometers in the Materials and Life Science Experimental Facility (MLF) at J-PARC, "DIRECTION 2017", was held at the Ibaraki Quantum Beam Research Center building on October 16th - 17th, 2017. This meeting was purposed to encourage the user activities on the four instruments 4SEASONS (BL01), HRC (BL12), AMATERAS (BL14), and POLANO (BL23), and was jointly organized by J-PARC MLF, KEK-IMSS, and CROSS. In this meeting, recent research activities using these instruments were reported in addition to the current status of the instruments, the sample environments, and software. This report compiles the presentation materials and their abstracts.

Journal Articles

Neutron scattering study of yttrium iron garnet

Shamoto, Shinichi; Ito, Takashi; Onishi, Hiroaki; Yamauchi, Hiroki; Inamura, Yasuhiro; Matsuura, Masato*; Akatsu, Mitsuhiro*; Kodama, Katsuaki; Nakao, Akiko*; Moyoshi, Taketo*; et al.

Physical Review B, 97(5), p.054429_1 - 054429_9, 2018/02

 Times Cited Count:5 Percentile:47.75(Materials Science, Multidisciplinary)

Nuclear and magnetic structure and full magnon dispersions of yttrium iron garnet Y$$_3$$Fe$$_5$$O$$_{12}$$ have been studied by neutron scattering. The lowest-energy dispersion below 14 meV exhibits a quadratic dispersion as expected from ferromagnetic magnons. The imaginary part of $$q$$-integrated dynamical spin susceptibility $$chi$$"($$E$$) exhibits a square-root energy-dependence in the low energies. The magnon density of state is estimated from the $$chi$$"($$E$$) obtained on an absolute scale. The value is consistent with a single chirality mode for the magnon branch expected theoretically.

Journal Articles

Materials and Life Science Experimental Facility (MLF) at the Japan Proton Accelerator Research Complex, 2; Neutron scattering instruments

Nakajima, Kenji; Kawakita, Yukinobu; Ito, Shinichi*; Abe, Jun*; Aizawa, Kazuya; Aoki, Hiroyuki; Endo, Hitoshi*; Fujita, Masaki*; Funakoshi, Kenichi*; Gong, W.*; et al.

Quantum Beam Science (Internet), 1(3), p.9_1 - 9_59, 2017/12

The neutron instruments suite, installed at the spallation neutron source of the Materials and Life Science Experimental Facility (MLF) at the Japan Proton Accelerator Research Complex (J-PARC), is reviewed. MLF has 23 neutron beam ports and 21 instruments are in operation for user programs or are under commissioning. A unique and challenging instrumental suite in MLF has been realized via combination of a high-performance neutron source, optimized for neutron scattering, and unique instruments using cutting-edge technologies. All instruments are/will serve in world-leading investigations in a broad range of fields, from fundamental physics to industrial applications. In this review, overviews, characteristic features, and typical applications of the individual instruments are mentioned.

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

Structure of the magnetic excitations in the spin-1/2 triangular-lattice Heisenberg antiferromagnet Ba$$_{3}$$CoSb$$_{2}$$O$$_{9}$$

Ito, Saya*; Kurita, Nubuyuki*; Tanaka, Hidekazu*; Kawamura, Seiko; Nakajima, Kenji; Ito, Shinichi*; Kuwahara, Keitaro*; Kakurai, Kazuhisa*

Nature Communications (Internet), 8, p.235_1 - 235_6, 2017/08

 Times Cited Count:31 Percentile:92.19(Multidisciplinary Sciences)

Journal Articles

Time-of-flight elastic and inelastic neutron scattering studies on the localized 4d electron layered perovskite La$$_5$$Mo$$_4$$O$$_{16}$$

Iida, Kazuki*; Kajimoto, Ryoichi; Mizuno, Yusuke*; Kamazawa, Kazuya*; Inamura, Yasuhiro; Hoshikawa, Akinori*; Yoshida, Yukihiko*; Matsukawa, Takeshi*; Ishigaki, Toru*; Kawamura, Yukihiko*; et al.

Journal of the Physical Society of Japan, 86(6), p.064803_1 - 064803_6, 2017/06

 Times Cited Count:0 Percentile:100(Physics, Multidisciplinary)

Journal Articles

Impurity effects in the microscopic elastic properties of polycrystalline Mg-Zn-Y alloys with a synchronised long-period stacking ordered phase

Hosokawa, Shinya*; Kimura, Koji*; Yamasaki, Michiaki*; Kawamura, Yoshihito*; Yoshida, Koji*; Inui, Masanori*; Tsutsui, Satoshi*; Baron, A. Q. R.*; Kawakita, Yukinobu; Ito, Shinichi*

Journal of Alloys and Compounds, 695, p.426 - 432, 2017/02

 Times Cited Count:3 Percentile:67.8(Chemistry, Physical)

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:19 Percentile:17.09(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

Nondestructive elemental depth-profiling analysis by muonic X-ray measurement

Ninomiya, Kazuhiko*; Kubo, Kenya*; Nagatomo, Takashi*; Higemoto, Wataru; Ito, Takashi; Kawamura, Naritoshi*; Strasser, P.*; Shimomura, Koichiro*; Miyake, Yasuhiro*; Suzuki, Takao*; et al.

Analytical Chemistry, 87(9), p.4597 - 4600, 2015/05

 Times Cited Count:11 Percentile:47.24(Chemistry, Analytical)

Journal Articles

Chromatographic separation of nuclear rare metals by highly functional xerogels

Onishi, Takashi; Koyama, Shinichi; Masud, R. S.*; Kawamura, Takuya*; Mimura, Hitoshi*; Niibori, Yuichi*

Nippon Ion Kokan Gakkai-Shi, 25(4), p.220 - 227, 2014/11

no abstracts in English

Journal Articles

Present status of J-PARC linac

Oguri, Hidetomo; Hasegawa, Kazuo; Ito, Takashi; Chishiro, Etsuji; Hirano, Koichiro; Morishita, Takatoshi; Shinozaki, Shinichi; Ao, Hiroyuki; Okoshi, Kiyonori; Kondo, Yasuhiro; et al.

Proceedings of 11th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.389 - 393, 2014/10

no abstracts in English

Journal Articles

Improvement of J-PARC klystron high voltage power supply

Chishiro, Etsuji; Kawamura, Masato*; Sagawa, Ryu*; Ogawa, Shinichi*

Proceedings of 11th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1091 - 1093, 2014/10

In J-PARC linac, six units of high voltage power supplies for 324 MHz klystrons have operated since 2006, and those running time exceed 35,000 hours. In addition, six units of power supplies for the 972 MHz klystrons have been operation since 2013. In the power supply, various troubles occur under the operation. In some anode modulators, arc discharge in the transformer oil had occurred due to the deterioration of the auxiliary solid insulator. In three modules combining a step-up transformer and a rectifier, the high voltage diode was breakdown because an unexpected overvoltage was applied. And by improving the voltage dividing resistor of the module, high stability cathode voltage was achieved. In this report, we describe the trouble and the improvement that occurred in the equipment.

Journal Articles

Present status of klystron power supply systems for J-PARC linac 2013

Kawamura, Masato*; Chishiro, Etsuji; Hori, Toshihiko; Shinozaki, Shinichi; Sato, Fumiaki; Fukui, Yuji*; Futatsukawa, Kenta*; Yamazaki, Masayoshi*; Sagawa, Ryu*; Miyajima, Noriyuki*; et al.

Proceedings of 10th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.605 - 607, 2014/06

This report describes the present status of the klystron power supply systems for the J-PARC linac. The systems for the 181 MeV linac were operated from September to May. A few breakdowns were occurred, and are described in this report. The new systems for the upgrade of the linac from 181MeV to 400 MeV have been installed until now, and the 3 HVDCPSs and the 3 anode modulators of the new systems have been operated. All the systems for 400 MeV linac will be operated in this autumn.

93 (Records 1-20 displayed on this page)