Measurement of radionuclide production probabilities in negative muon nuclear capture and validation of Monte Carlo simulation model

Yamaguchi, Yuji; Niikura, Megumi*; Mizuno, Rurie*; Tampo, Motonobu*; Harada, Masahide; Kawamura, Naritoshi*; Umegaki, Izumi*; Takeshita, Soshi*; Haga, Katsuhiro

Nuclear Instruments and Methods in Physics Research B, 567, p.165801_1 - 165801_11, 2025/10

https://doi.org/10.1016/j.nimb.2025.165801

As part of the development of a sample radioactivity calculation program, we have measured radionuclide production probabilities in negative muon nuclear capture to update experimental data and to validate a calculation dataset obtained by a Monte Carlo simulation code. The probabilities have been obtained by an activation experiment on Al, Si, Co, and Ta targets. The obtained probabilities expand the validation scope to the radionuclide production processes outside of the existing data coverage. By comparing the resultant probabilities with the calculated dataset, it has been revealed that the dataset is generally on the safe side in radioactivity estimation and needs to be corrected in the following three cases: (i) isomer production; (ii) radionuclide production by the multiple neutron emission; (iii) radionuclide production by particle emissions involving a proton. The present probabilities and the new findings on the correction provide valuable clues to improvements of the simulation models.

State-of-the-art beam loss minimization at high-intensity beam operation of the 3 GeV rapid cycling synchrotron at the Japan Proton Accelerator Research Complex

Saha, P. K.; Harada, Hiroyuki; Tamura, Fumihiko; Okabe, Kota; Yoshimoto, Masahiro; Shobuda, Yoshihiro; Okita, Hidefumi; Kojima, Kunihiro; Nakanoya, Takamitsu; Hatakeyama, Shuichiro; et al.

Physical Review Accelerators and Beams (Internet), 28(7), p.074201_1 - 074201_23, 2025/07

https://doi.org/10.1103/tbyh-jcq3

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.

Simulation study on dose and LET of neutron irradiation for biological experiments using spallation, reactor, and compact neutron sources

Sweet, M.*; Mishima, Kenji*; Harada, Masahide; Kurita, Keisuke; Iikura, Hiroshi; Tasaki, Seiji*; Kikuchi, Norio*

Quantum Beam Science (Internet), 9(2), p.11_1 - 11_17, 2025/04

https://doi.org/10.3390/qubs9020011

Neutron beam, being electrically neutral and highly penetrating, offers unique advantages for irradiation of biological species such as plants, seeds, and microorganisms. We comprehensively investigated the potential of neutron irradiation for inducing genetic mutations using simulations of J-PARC BL10, JRR-3 TNRF, and KUANS for spallation, reactor, and compact neutron sources.

First measurement of missing energy due to nuclear effects in monoenergetic neutrino charged-current interactions

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

Physical Review Letters, 134(8), p.081801_1 - 081801_9, 2025/02

https://doi.org/10.1103/PhysRevLett.134.081801

Report on the 21st Annual Meeting of Particle Accelerator Society of Japan

Iwai, Takeo*; Tokanai, Fuyuki*; Soda, Hikaru*; Harada, Hiroyuki

Kasokuki, 21(4), p.381 - 386, 2025/01

https://doi.org/10.50868/pasj.21.4_381

no abstracts in English

Application of energy-resolving neutron imaging to major-component analyses of materials using four-channel superconducting detector

Vu, TheDang*; Shishido, Hiroaki*; Aizawa, Kazuya; Oku, Takayuki; Oikawa, Kenichi; Harada, Masahide; Kojima, Kenji M*; Miyajima, Shigeyuki*; Soyama, Kazuhiko; Koyama, Tomio*; et al.

IEEJ Transactions on Electrical and Electronic Engineering, 19(11), p.1888 - 1894, 2024/11

https://doi.org/10.1002/tee.24144

Study on the mitigation of the beam loss for further beam power ramp-up in J-PARC RCS

Kojima, Kunihiro; Harada, Hiroyuki; Chimura, Motoki; Saha, P. K.

Proceedings of 21st Annual Meeting of Particle Accelerator Society of Japan (Internet), p.118 - 122, 2024/10

https://www.pasj.jp/web_publish/pasj2024/proceedings/PDF/THOA/THOA05.pdf

Further beam power ramp-up going beyond the design output beam power of 1 MW is proceeding in the J-PARC RCS. In MW-class rings, the residual radioactivity accompanying the beam loss strictly limits the available beam power. While the current beam loss is mitigated to 0.1% level at the designed beam power, further beam loss mitigation prepared for the beam power ramp-up is required. The resonance crossing of the tune spread can cause unallowable beam loss. Since the beam power ramp-up definitely extends the space-charge-induced tune spread, the sufficiently wide stability region in the betatron tune map must be secured for low beam loss. We conducted low-intensity beam studies on the half-integer random resonances that likely have significant effects on the width of the stability region. Thanks to the simplification coming from the mitigation of the space-charge force, the successful compensation of the resonance is realized by using the trim quadrupole magnets. In the high-intensity beam studies, the resonance compensation was found to be beneficial in extending the stability region.

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.

Data assimilation using deterministic sampling method to selectively reduce uncertainty due to thermal neutron scattering law for light water

Harada, Yoshinari*; Yamaguchi, Hibiki*; Endo, Tomohiro*; Yamamoto, Akio*; Tada, Kenichi

Transactions of the American Nuclear Society, 130(1), p.758 - 762, 2024/06

The data assimilation was performed using deterministic sampling to selectively reduce uncertainties caused by the thermal neutron scattering in light water. The prompt neutron decay constant of the water tank system was used for the data assimilation. The deterministic sampling method was applied to uncertainty quantification and data assimilation for light water thermal neutron scattering law data obtained by the CAB model. The uncertainty quantification results using the deterministic sampling method were comparable to those using the random sampling method.