Preliminary neutronic performances of Spallation Neutron Source of Second Target Station at Materials and Life Science Experimental Facility in J-PARC

Harada, Masahide

JPS Conference Proceedings (Internet), 45, p.011042_1 - 011042_6, 2026/06

https://doi.org/10.7566/JPSCP.45.011042

At Materials and Life science Facility (MLF) in J-PARC, 3 GeV and 1MW proton beam induces a carbon target and a mercury target to provide muon beam and neutron beam, respectively. The first target station of MLF, "TS1", started to operate from 2008 and stably operates with nearby 1MW as of April 2024. As an upgrade of MLF, the second target station, "TS2", is being planned. TS2 is located near TS1 and the proton beam line to TS2 is divided at halfway to the TS1 proton beam line. Total proton beam power supplied by accelerators increases to 1.5MW. Although the repetition rate is still 25Hz, 1 of 3 pulses are transported to TS2, resulting in 8.3Hz and 0.5MW of proton beam to TS2. TS2 has a tungsten rotating target to provide both neutron and muon, and moderators to provide much higher neutron brightness by adopting higher current density of proton beam, a closer moderator position to the target, a flatter moderator and so on. Beryllium and Iron are chosen as reflector materials. The rotating target cooled by helium gas is also expected to increase neutron and muon intensities with a coexistence of them. Details of TS2 plan are summarized in Ref. In order to provide high intensity neutrons, optimization studies of TS2 were performed by the simulation code PHITS and MCNP. Finally, the coupled moderator of TS2 can provide 4 times higher intensity than that of TS1. If smaller height of moderator is chosen, brightness increases to 8 times compared with TS1. Decoupled moderators of TS2 also provide 3 time higher than that of TS1. A fixed solid target case was also compared.

Sample Radioactivity Evaluation Program (SARE) at Materials and Life Science Facility in J-PARC

Harada, Masahide; Yamaguchi, Yuji; Hashimoto, Norimichi*; Ito, Taku*; Tajima, Takahiro*; Oku, Takayuki; Haga, Katsuhiro; Ikeda, Hiroshi*; Tamura, Satoshi*

JPS Conference Proceedings (Internet), 45, p.011184_1 - 011184_4, 2026/06

https://doi.org/10.7566/JPSCP.45.011184

At Materials and Life Science Facility in J-PARC, 3 GeV and 1 MW pulsed proton beam hits mercury and carbon targets and intense neutron and muon beams are provided for various measurements. As samples in the measurements are activated, estimation of radioactivity of samples is very necessary for a radiation safety of user experiments. Therefore, estimation system, SAmple Radioactivity Evaluation program (SARE), is developed. SARE can estimate radioactivity of samples at each neutron and muon beam line with neutron flux and activation cross section. The neutron flux data was applied from references and the activation cross section data was obtained from DCHAIN-SP-2001. The activation of negative-muon can be also estimated from a database. SARE has a user-friendly interface of Web servlet based on JAVA and JAVA script and can select various conditions for the estimation. In the presentation, we will introduce SARE and validation results performed at BL10 with the foil-activation method.

Development of a compact He neutron spin filter at J-PARC

Takahashi, Shingo; Kiyanagi, Ryoji; Okudaira, Takuya*; Takada, Shusuke*; Kobayashi, Ryuju; Okuizumi, Mao; Ino, Takashi*; Asai, Kanta*; Tsuchikawa, Yusuke; Oikawa, Kenichi; et al.

Nuclear Instruments and Methods in Physics Research A, 1075, p.170410_1 - 170410_8, 2025/06

https://doi.org/10.1016/j.nima.2025.170410

Neutron target for high-intensity operation at J-PARC MLF

Haga, Katsuhiro; Naoe, Takashi; Kogawa, Hiroyuki; Wakui, Takashi; Kinoshita, Hidetaka; Harada, Masahide

Proceedings of 16th International Particle Accelerator Conference (IPAC25) (Internet), p.3245 - 3249, 2025/06

https://doi.org/10.18429/JACoW-IPAC2025-FRXD1

In April 2024, the beam power at MLF attained 950 kW for the first time for long term user operation, and the beam power at the 3 GeV rapid cycle synchrotron (RCS) outlet was raised to 1 MW. This accomplishment means that the goal of the stable operation of the neutron source with 1 MW was almost achieved at last, and it's time to go on to the new stage of the neutron source R&D. There are two major challenges for the mercury target in the next stage. One is to attain the long-term operation of a mercury target. The service life of the target vessel is primarily determined by cavitation damage that occurs on the inner surface due to the injection of high-intensity pulsed proton beams. Until now, the vessel has been replaced annually to inspect the extent of the damage. However, based on the damage data obtained during 1 MW high-power operation, it has been determined that the vessel can withstand long-term operation for more than two years. Therefore, a new target vessel, which was replaced in 2024, is scheduled to be used for an extended period through 2027. Furthermore, since there are plans to increase the pulse intensity of the RCS in the future, it will be necessary to develop more effective pitting damage suppression techniques and new target vessels that can withstand even stronger proton beam pulses. In this presentation, the present status of the neutron source of MLF and future operation plans will be shown.

Evaluation of the performance of event reconstruction algorithms in the JSNS experiment using a Cf calibration source

Lee, D. H.*; Dodo, Taku; Haga, Katsuhiro; Harada, Masahide; Hasegawa, Shoichi; Kasugai, Yoshimi; Kinoshita, Hidetaka; Masuda, Shiho; Meigo, Shinichiro; Sakai, Kenji; et al.

Nuclear Instruments and Methods in Physics Research A, 1072, p.170216_1 - 170216_6, 2025/03

https://doi.org/10.1016/j.nima.2025.170216

Pulse shape discrimination in JSNS

Dodo, Taku; Haga, Katsuhiro; Harada, Masahide; Hasegawa, Shoichi; Kasugai, Yoshimi; Kinoshita, Hidetaka; Masuda, Shiho; Meigo, Shinichiro; Sakai, Kenji; Suzuya, Kentaro; et al.

Progress of Theoretical and Experimental Physics (Internet), 2025(2), p.023H02_1 - 023H02_8, 2025/02

https://doi.org/10.1093/ptep/ptaf016

Atomic imaging of BaTiO by multiple-wavelength neutron holography

Yamakawa, Kota*; Nakada, Hajime*; Kimura, Koji*; Oikawa, Kenichi; Harada, Masahide; Inamura, Yasuhiro; Oyama, Kenji*; Hayashi, Koichi*

Journal of the Physical Society of Japan, 93(10), p.104601_1 - 104601_5, 2024/10

https://doi.org/10.7566/JPSJ.93.104601

Dataset of nuclide production from nuclear capture reaction of negative muon based on Monte Carlo simulation

Yamaguchi, Yuji; Harada, Masahide; Haga, Katsuhiro

JAEA-Data/Code 2024-008, 91 Pages, 2024/08

JAEA-Data-Code-2024-008.pdf:1.24MB
JAEA-Data-Code-2024-008-appendix(CD-ROM).zip:0.09MB

We have produced a dataset of the yields of radionuclides produced by the nuclear capture of negative muons applying Monte Carlo calculation due to scarce experimental data for the sake of radiation safety of experimental facilities which can provide negative muons. The dataset covers all the stable targets of natural elements. The use of the dataset is described in an example of radioactive estimation for a negative-muon-irradiated sample. The dataset reported is fundamental data expected to be utilized in experiments with negative muons of various fields including radiation safety.

Study on the accidental background of the JSNS experiment

Lee, D. H.*; Dodo, Taku; Haga, Katsuhiro; Harada, Masahide; Hasegawa, Shoichi; Kasugai, Yoshimi; Kinoshita, Hidetaka; Masuda, Shiho; Meigo, Shinichiro; Sakai, Kenji; et al.

European Physical Journal C, 84, p.409_1 - 409_6, 2024/04

https://doi.org/10.1140/epjc/s10052-024-12778-7

The Acrylic vessel for JSNS-II neutrino target

Shin, C. D.*; Dodo, Taku; Haga, Katsuhiro; Harada, Masahide; Hasegawa, Shoichi; Kasugai, Yoshimi; Kinoshita, Hidetaka; Masuda, Shiho; Meigo, Shinichiro; Sakai, Kenji; et al.

Journal of Instrumentation (Internet), 18(12), p.T12001_1 - T12001_9, 2023/12

https://doi.org/10.1088/1748-0221/18/12/T12001