Proposal of maintenance rationalization for next-generation fast reactors based on the analysis of the prolonged maintenance of the prototype fast-breeder reactor in Japan, "Monju", 2; Analysis of maintenance plan of "Monju" in reactor cold shutdown

Toyota, Kodai; Hashidate, Ryuta; Takahashi, Keita; Yada, Hiroki; Takaya, Shigeru

Hozengaku, 20(2), p.95 - 103, 2021/07

Upgrade of the 3-MeV linac for testing of accelerator components at J-PARC

Kondo, Yasuhiro; Hirano, Koichiro; Ito, Takashi; Kikuzawa, Nobuhiro; Kitamura, Ryo; Morishita, Takatoshi; Oguri, Hidetomo; Okoshi, Kiyonori; Shinozaki, Shinichi; Shinto, Katsuhiro; et al.

Journal of Physics; Conference Series, 1350, p.012077_1 - 012077_7, 2019/12

https://doi.org/10.1088/1742-6596/1350/1/012077

We have upgraded a 3-MeV linac at J-PARC. The ion source is same as the J-PARC linac's, and the old 30-mA RFQ is replaced by a spare 50-mA RFQ, therefore, the beam energy is 3 MeV and the nominal beam current is 50 mA. The main purpose of this system is to test the spare RFQ, but also used for testing of various components required in order to keep the stable operation of the J-PARC accelerator. The accelerator has been already commissioned, and measurement programs have been started. In this paper, present status of this 3-MeV linac is presented.

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

https://doi.org/10.7566/JPSCP.25.011024

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).

Anomaly of structural relaxation in complex liquid metal of bismuth; Dynamic correlation function of coherent quasi-elastic neutron scattering

Kawakita, Yukinobu; Kikuchi, Tatsuya*; Inamura, Yasuhiro; Tahara, Shuta*; Maruyama, Kenji*; Hanashima, Takayasu*; Nakamura, Mitsutaka; Kiyanagi, Ryoji; Yamauchi, Yasuhiro*; Chiba, Kaori*; et al.

Physica B; Condensed Matter, 551, p.291 - 296, 2018/12

https://doi.org/10.1016/j.physb.2017.12.037

There are elemental liquid metals with complex structures far from the hard sphere (HS) packing model. Liquid Bi has an asymmetric first peak in the structure factors S(Q). The pair distribution function g(r) exhibits strange distance ratio of 1:2 between the first and the second peaks. Since a HS model with two kinds of radius produces asymmetry of the main peak in S(Q), existence of short-lived covalent bonds was discussed. Contrarily, modulation of the atomic distribution by the Friedel oscillations of shielding electrons around metallic ions was discussed. To examine its bonding nature from viewpoints of dynamic correlation functions, we have measured neutron quasielastic scattering of liquid Bi by using cold disk chopper spectrometer installed at MLF of J-PARC. The van Hove function revealed that the shoulder structure located at a longer side of the first peak in g(r) exhibits a longer relaxation time than the main structures such as the first and second peaks.

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

https://doi.org/10.3233/JNR-170046

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 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 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.

Inter-atomic force constants of BaF by diffuse neutron scattering measurement

Sakuma, Takashi*; Makhsun*; Sakai, Ryutaro*; Xianglian*; Takahashi, Haruyuki*; Basar, K.*; Igawa, Naoki; Danilkin, S. A.*

AIP Conference Proceedings 1656, p.020002_1 - 020002_4, 2015/04

https://doi.org/10.1063/1.4917089

Diffuse neutron scattering measurement on BaF crystals was performed at 10 K and 295 K. Oscillatory form in the diffuse scattering intensity of BaF was observed at 295 K. The correlation effects among thermal displacements of F-F atoms were obtained from the analysis of oscillatory diffuse scattering intensity. From the values of correlation effects and Debye-Waller temperature parameters, force constants among the first and second nearest neighboring atoms of BaF, were determined to be 4.40 and 2.30 eV/ at 295 K, respectively

Development of a GEM-TPC for H-dibaryon search experiment at J-PARC

Sako, Hiroyuki; Ahn, J. K.*; Baek, K. H.*; Bassalleck, B.*; Fujioka, H.*; Guo, L.*; Hasegawa, Shoichi; Hicks, K.*; Honda, R.*; Hwang, S. H.*; et al.

Journal of Instrumentation (Internet), 9(4), p.C04009_1 - C04009_10, 2014/04

https://doi.org/10.1088/1748-0221/9/04/C04009

A TPC has been developed for J-PARC E42 experiment to search for H-dibaryon in (, ) reaction. An event with 2 and 2 protons decaying from H-dibaryon is searched for inside the TPC. The TPC has octagonal prism shape drift volume with about 50 cm diameter with 55 cm drift length filled with Ar-CH (90:10) gas. At the end of the drift volume, 3-layer GEMs are equipped. In order to analyze momenta of produced particles, the TPC is applied with 1 T dipole magnetic field parallel to the drift electric field with a superconducting Helmholz magnet. In order to maximize the acceptance of H-dibaryon events, a diamond target is installed inside the TPC drift volume, in a cylindrical hole opened from the top to the middle of the drift volume. Since extremely high-rate beam is directly injected into the TPC drift volume to the target, a gating grid and GEMs are adopted to suppress positive-ion feedback.

Development of multi-purpose MW gyrotrons for fusion devices

Minami, Ryutaro*; Kariya, Tsuyoshi*; Imai, Tsuyoshi*; Numakura, Tomoharu*; Endo, Yoichi*; Nakabayashi, Hidetaka*; Eguchi, Taku*; Shimozuma, Takashi*; Kubo, Shin*; Yoshimura, Yasuo*; et al.

Nuclear Fusion, 53(6), p.063003_1 - 063003_7, 2013/06

https://doi.org/10.1088/0029-5515/53/6/063003

Force constants of Cu crystals from diffuse neutron scattering measurement

Sakuma, Takashi*; Mohapatra, S. R.*; Uehara, Hiroyuki*; Sakai, Ryutaro*; Xianglian*; Takahashi, Haruyuki*; Igawa, Naoki; Basar, K.*

Atom Indonesia, 36(3), p.121 - 124, 2010/12

https://doi.org/10.17146/aij.2010.28

Diffuse neutron scattering measurement on Cu crystals was performed at 10 K and 300 K and the observed diffuse scattering intensities were analyzed by including the correlation effects among thermal displacements of atoms in the theory. Using the values of correlation effects among neighboring atoms and the values of Debye-Waller temperature parameter, force constants among first, second and third nearest neighboring atoms had been evaluated. The estimated values of force constants among first, second and third nearest neighboring atoms of Cu were 5.58, 3.63 and 2.37 eV/ at 300 K, respectively. The relation between correlation effects and the inter-atomic distance is not depending much on the crystal binding types.

Lifetime measurements for the first 2 states in Gd populated by the decay of Eu

Nagae, Daisuke*; Ishii, Tetsuro; Takahashi, Ryuta*; Asai, Masato; Makii, Hiroyuki; Osa, Akihiko; Sato, Tetsuya; Ichikawa, Shinichi; Shimizu, Yoshifumi*; Shoji, Takuya*

AIP Conference Proceedings 1224, p.156 - 160, 2010/04

https://doi.org/10.1063/1.3431410