X ray spectroscopy on atoms (J-PARC E03, E07 and future)

Yamamoto, Takeshi; Fujita, Manami; Gogami, Toshiyuki*; Harada, Takeshi*; Hayakawa, Shuhei*; Hosomi, Kenji; Ichikawa, Yudai; Ishikawa, Yuji*; Kamata, K.*; Kanauchi, H.*; et al.

EPJ Web of Conferences, 271, p.03001_1 - 03001_5, 2022/11

https://doi.org/10.1051/epjconf/202227103001

Study of interaction from the scattering experiment at J-PARC

Miwa, Koji*; Fujita, Manami; Hasegawa, Shoichi; Hosomi, Kenji; Ichikawa, Masaya; Ichikawa, Yudai; Imai, Kenichi*; Nanamura, Takuya; Naruki, Megumi; Sako, Hiroyuki; et al.

Journal of Physics; Conference Series, 1643, p.012174_1 - 012174_6, 2020/12

https://doi.org/10.1088/1742-6596/1643/1/012174

High statistics scattering experiment using high intensity pion beams at J-PARC

Miwa, Koji*; Hasegawa, Shoichi; Hayakawa, Shuhei; Hosomi, Kenji; Imai, Kenichi; Kondo, Yasuhiro; Naruki, Megumi; Sako, Hiroyuki; Sato, Susumu; Sugimura, Hitoshi; et al.

JPS Conference Proceedings (Internet), 17, p.041002_1 - 041002_6, 2017/07

https://doi.org/10.7566/JPSCP.17.041002

A Beam position fiber counter with scintillation fibers and multi-pixel photon counter for high intensity beam operation

Honda, Ryotaro*; Miwa, Koji*; Matsumoto, Yuki*; Chiga, Nobuyuki*; Hasegawa, Shoichi; Imai, Kenichi

Nuclear Instruments and Methods in Physics Research A, 787, p.157 - 160, 2015/07

https://doi.org/10.1016/j.nima.2014.11.084

A beam position fiber counter consisting of the scintillation fiber and a multi-pixel photon counter was developed in order to handle a 10 MHz secondary pion beam in the J-PARC E40 experiment. This counter was installed at the entrance of the beam line spectrometer at the K1.8 experimental area in J-PARC and used for the momentum reconstruction. In order to suppress the accidental background and reconstruct the beam momentum, a good timing resolution better than 0.8 ns and a good position resolution better than 200 m were simultaneously required for the counter. These requirements were well achieved by reading the 320 fibers with a diameter of 1 mm, which were arranged in a staggered position, with MPPC fiber by fiber. The signal induced from each MPPC was handled with an Extended Analogue SiPM Integrated ReadOut Chip (EASIROC) developed by Omega/IN2P3 in France. In addition, the timing of the discriminated signals from EASIROC was measured by a FPGA-based multi-hit TDC implemented into Spartan-6. Finally, we obtained the timing resolution of 0.68 ns and the position resolution of 190 m under the 9 MHz beam condition using a pion beam.

In-situ SCC observation of thermally-sensitized and cold-worked type 304 stainless steel irradiated to a neutron fluence of 110n/m

Nakano, Junichi; Nemoto, Yoshiyuki; Miwa, Yukio; Usami, Koji; Tsukada, Takashi; Hide, Koichiro*

Journal of Nuclear Materials, 386-388, p.281 - 285, 2009/04

https://doi.org/10.1016/j.jnucmat.2008.12.114

Crack initiation and crack growth processes of irradiation assisted stress corrosion cracking on stainless steels were studied by slow strain rate testing in oxygenated high temperature water at 561 K. In-situ observation was carried out during SSRT. Specimens of type 304 stainless steel were subjected to a solution annealing (SA), a thermally sensitization (TS), or a cold working (CW) and irradiated to 1.010 n/m (E 1 MeV) at 323 K in the Japan Material Testing Reactor (JMTR). Crack initiations were observed before the maximum stress would be reached for the CW material in in-situ observation. In fracture surface examination, the TS material exhibited almost intergranular stress corrosion cracking while mixtures of transgranular stress corrosion cracking and ductile dimple fracture were observed for the SA and the CW materials.

Grain boundary character of cracks observed in IASCC and IGSCC

Miwa, Yukio; Kaji, Yoshiyuki; Tsukada, Takashi; Kato, Yoshiaki; Tomita, Takeshi; Nagata, Nobuaki*; Dozaki, Koji*; Takiguchi, Hideki*

Proceedings of 13th International Conference on Environmental Degradation of Materials in Nuclear Power Systems (CD-ROM), 14 Pages, 2007/00

Grain boundary (GB) character of cracks observed in irradiation assisted stress corrosion cracking (IASCC) and in intergranular stress corrosion cracking (IGSCC) was examined using the orientation imaging microscope (OIM). IASCC were produced by constant load tests with 1/4T-CT specimens for pre-irradiated (1.8 dpa at 546 K) type 304 stainless steel. The tests for pre-irradiated specimens were performed by the post irradiation SCC test or the in-reactor SCC test at the Japan Materials Testing Reactor. In all specimens, cracks propagated mainly along random grain boundaries (GBs), and small amount of cracks propagated along low angle GBs ( 1), twin GBs ( 3) and coincidence site lattice (CSL) GBs ( 5-27). Fraction of the GB character was compared with the author's previous studies in which the fraction of IGSCC in thermally-sensitized type 304 stainless steel and unirradiated type 316L stainless steel were measured on CT specimens and a BWR shroud sample. The relationship between SCC behavior and the GB character was discussed. It was considered that the difference of the fraction of GB character between IASCC and IGSCC related to the deformation mode of irradiated stainless steel such as dislocation channelling.

Beam-palarization asymmetries for the (,) and (,) reactions for =1.5-2.4 GeV

Zegers, R. G. T.*; Sumihama, Mizuki*; Ahn, D. S.*; Ahn, J. K.*; Akimune, Hidetoshi*; Asano, Yoshihiro; Chang, W. C.*; Dat, S.*; Ejiri, Hiroyasu*; Fujimura, Hisako*; et al.

Physical Review Letters, 91(9), p.092001_1 - 092001_4, 2003/08

https://doi.org/10.1103/PhysRevLett.91.092001

no abstracts in English

Distribution and feature of fracture zone in fault steps; An Eexample of the western part of the Atotsugawa Fault

Niwa, Masakazu; Shimada, Koji; Nohara, Tsuyoshi; Miwa, Atsushi*; Kurosawa, Hideki*

no journal, , 

Detailed topographical and geological researches for understanding fracture zone structures in fault steps are necessary to estimate the extent of the mechanical damage to basement rocks due to strike-slip fault activities. Our research of the western part of the Atotsugawa Fault in the Hida City, Gifu Prefecture shows that the faults high-angle oblique to the principal direction of the Atotsugawa Fault characteristically occur in fault steps, which effect that the fracture zone increases in width. The Atotsugawa fault, which is one of the Class A active faults, trends ENE-WSW and shows dextral strike-slip displacement. We firstly checked the occurrence of the fault step in the Miyagawa-cho area of the western part of the Atotsugawa Fault by way of aerial photograph interpretation. Then we researched the distribution and feature of fracture zone in the Kawai-cho area where the fault continues lineally and in the Miyagawa-cho area where the fault steps. In the Kawai-cho area, Fault planes mostly strike ENE-WSW to E-W and dip steeply N or S, subparallel to the principal direction of the Atotsugawa Fault. Width of the fracture zone is several tens meters. In the Miyagawa-cho area, NW-SE and N-S strike faults dominantly occur as well as ENE-WSW to E-W strike faults. Width of the fracture zone is more than a hundred meter. Remarkable existence of NW-SE and N-S strike faults distinguishes the fracture zone in the Miyagawa-cho area as that in the Kawai-cho area.

Electrochemical potential measurement of stainless steel in BWR water environment under high radiation field at JMTR

Miwa, Yukio; Tsukada, Takashi; Sato, Tomonori; Hanawa, Satoshi; Matsui, Yoshinori; Nagata, Nobuaki*; Dozaki, Koji*; Takiguchi, Hideki*

no journal, , 

no abstracts in English

Investigation of crack initiation behavior using pre-irradiated austenitic stainless steel at JMTR

Tsukada, Takashi; Ugachi, Hirokazu; Kaji, Yoshiyuki; Miwa, Yukio; Nakano, Junichi; Matsui, Yoshinori; Endo, Shinya; Kato, Yoshiaki; Nagata, Nobuaki*; Dozaki, Koji*; et al.

no journal, , 

Irradiation Assisted Stress Corrosion Cracking (IASCC) has been regarded in recent years as the matter that is related to the reliability for core components of LWRs. The in-pile IASCC initiation tests were performed using of uniaxial constant load specimens pre-irradiated to about 510n/m and 110n/m at JMTR under the simulated BWR core condition. From the results of in-pile and out-of-pile tests of the irradiated specimens, we confirmed that any remarkable acceleration effect of synergy of neutron/ radiation and stress/water environment on SCC initiation results was not observed under the test condition of this study. On the surface of in-pile test specimen, a micro crack was observed on the surface of specimen, and it was considered to be an initiation of SCC besed on the results of out-of-pile experiments.

Analysis status of scattering events in the J-PARC E40 experiment

Nanamura, Takuya; Ichikawa, Yudai; Hayakawa, Shuhei; Yoshida, Junya; Miwa, Koji*; Honda, Ryotaro*; Akazawa, Yuya*; Yamamoto, Takeshi

no journal, , 

Hyperon-nucleon scattering experiment is one of the powerful methods for studying YN interaction. However, it is difficult due to short lifetime of hyperon. scattering experiments were performed as KEK E251 and KEK E289 in order to measure the differential cross sections. In these experiments, statistics were limited to less than 100 events and differential cross section had too large statistical errors to restrict baryon-baryon interaction models. J-PARC E40 experiment aims for measuring cross sections of scatterings with high statistics (10000 events) by overcoming difficulties of hyperon-nucleon scattering experiment. By using high rate ( 19M /spill) beam and large acceptance spectrometer, we can produce and tag large amount of beam. LH target and surrounding detector system CATCH enable us to reconstruct reactions from two body kinematics. Our experimental group completed data taking and about half of data taking by 2019 Apr. Left data taking will be performed in the end of this fiscal year.