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To, Kentaro; Nakamura, Tatsuya; Sakasai, Kaoru; Yamagishi, Hideshi*
JPS Conference Proceedings (Internet), 45, p.011201_1 - 011201_8, 2026/06
Ag(p,X) reaction at J-PARCSugihara, Kenta*; Meigo, Shinichiro; Iwamoto, Hiroki; Maekawa, Fujio
JPS Conference Proceedings (Internet), 45, p.011181_1 - 011181_10, 2026/06
It is essential to estimate the residual gamma-ray dose rate at accelerator facilities, such as accelerator-driven system. Even though improvements of computer performance enabled us to predict nuclide production cross sections by physics models, the prediction accuracy of the models should be confirmed more. Thus, we have been measuring the nuclide production cross sections by the proton bombardment on various targets with activation technique at J-PARC. In this study, we measured nuclide production cross section of the Ag(p,X) reaction.
Tamura, Jun; Kondo, Yasuhiro; Yee-Rendon, B.; Meigo, Shinichiro; Maekawa, Fujio; Kako, Eiji*; Umemori, Kensei*; Sakai, Hiroshi*; Domae, Takeshi*
JPS Conference Proceedings (Internet), 45, p.011171_1 - 011171_7, 2026/06
LaNakabe, Rintaro; Endo, Shunsuke; Kambara, Wataru*; Kimura, Atsushi; Kobayashi, Ryuju; Oku, Takayuki; Sakai, Kenji; Shinohara, Takenao; Takahashi, Ryuta*; Tsuchikawa, Yusuke; et al.
JPS Conference Proceedings (Internet), 45, p.011066_1 - 011066_5, 2026/06
We evaluate the time-reversal invariance violation using previous neutron transmission data with polarized neutrons propagating through a transversely polarized La. By incorporating precise spin observables and the scattering amplitudes into our analysis, we preliminarily constrained the time-reversal invariance violating cross section.
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
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.
Harada, Masahide
JPS Conference Proceedings (Internet), 45, p.011042_1 - 011042_6, 2026/06
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.
Harada, Masahide; Tajima, Takahiro*; Ito, Taku*; Masuda, Shiho; Kinoshita, Hidetaka; Sakai, Kenji; Muto, Giichi*; Suzuki, Akio*; Haga, Katsuhiro
JPS Conference Proceedings (Internet), 45, p.011053_1 - 011053_5, 2026/06
At Materials and Life science experimental Facility (MLF) in J-PARC, a mercury target of an intense pulsed spallation neutron source is designed to be irradiated by 3 GeV and 1MW proton beams to provide high intensity neutron beams to a suit of neutron instruments. A unified mercury radioactivity monitor (UHAM) is installed to find an indication of failure of the mercury target and loop system by detecting radioactive materials leaked from the system with a gamma-ray energy analysis with Germanium semi-conductor detectors. It is composed of three units of sampling port and radiation monitors: 1) HAM for interstitial helium gas layer between the mercury vessel and surrounding water shroud of the mercury target, 2) CAM for atmosphere in the hot cell where the target loop is operated and 3) VAM for helium gas in the helium vessel where the target vessel is installed. Once any leakages of radioactive materials are detected, an alarm signal is issued immediately to the accelerator control system to stop beam operation. Software and hardware have been upgraded yearly. For example, two Ge detectors are used for HAM for redundancy, NaI Scintillation detectors are also used as supplemental for the Ge detector to keep availability of the system for high counting rate event. In addition, A gas monitor is equipped at CAM to detect tritium. Until now, several operation experiences could be obtained as the follwoing. 1) Xe-121 and Xe-123 gas could be detected at CAM. These radio-active gaseous radioactive nuclides are slightly leaked from cover gas of mercury target. 2) Humidity in the helium vessel could be detected at VAM, because detection of annihilation gamma-ray and N-15 were increased. 3) The detection of Ar-41 indicated the air mixing in helium atmosphere.
Shibata, Takanori*; Nakano, Haruhisa*; Wada, Motoi*; Shinto, Katsuhiro; Okoshi, Kiyonori; Nammo, Kesao*; Kawai, Isao*; Oguri, Hidetomo
JPS Conference Proceedings (Internet), 45, p.011154_1 - 011154_8, 2026/06
In the high-power proton accelerator facilities, Radio Frequency (RF) driven negative hydrogen ion (H
) sources are adopted as particle sources for the maintenance-free duration over several months and for the stability of the H beam characteristics in the long-term operation. Techniques of RF plasma excitation are also introduced in the fusion field as ion sources of the neutral beam injection (NBI). On the other hand, the RF ion sources have a feature that the extracted beam current and phase space show slight oscillation with input RF frequency. The oscillation of the phase space may lead to mismatches of Twiss parameters or beam loss at the accelerator cavities in the higher-power beam operation. A 3D Particle-In-Cell (PIC) modeling based on Monte-Carlo collision was developed to elucidate the beam oscillation mechanisms. The presentation reports the effects upon the beam formation due to the electric potential fluctuation caused by a capacitive coupling to the internal antenna coil.
Naoe, Takashi; McClintock, D.*
JPS Conference Proceedings (Internet), 45, p.011169_1 - 011169_7, 2026/06
Mercury target vessel for the pulsed spallation neutron source suffers two kinds of cyclic stress during operation. One is the thermal stress due to the internal heating and swings by proton beam trip. The other is the impulsive stress by the pressure waves generated by the proton beam injection. The total number of loading cycles for the former is 
, and the later is 
for 2 years operation in the J-PARC mercury target vessel. The target vessel is made of 316L stainless steels and assembled by electron beam welding (EBW) and gas tungsten arc welding (GTAW). However, fatigue data of welded 316L stainless steels up to gigacycle is insufficient. Ultrasonic fatigue test, applying load cycle by utilizing ultrasonic resonance, for the welded metals were performed to investigate the effect of welding on gigacycle fatigue behavior. Fatigue strength of EBW and EB+GTAW specimens including weld bead effect will be discussed.
Iwamoto, Hiroki; Meigo, Shinichiro; Sugihara, Kenta*
JPS Conference Proceedings (Internet), 45, p.011179_1 - 011179_7, 2026/06
The nuclide production cross sections are crucial for evaluating the radioactivity of activation products in accelerators and nuclear facilities. Although the production of radionuclides in spallation reactions can be explained using physics models like the nuclear cascade plus evaporation model, accurately and comprehensively reproducing experimental values remains challenging. To address this problem, we have developed a machine learning (ML) model to comprehensively estimate nuclide production cross sections for target materials. The model is trained on experimental data from the nuclear reaction database EXFOR and can estimate nuclide production cross sections even in data-poor regions by utilizing transfer learning. In a previous study, we demonstrated that our model can comprehensively estimate 
Be (
d) and 
H (
y) production cross sections for a wide range of targets. In this study, we apply the ML model to nuclides important for accelerator facility design and astrophysics, such as He, 
Be (
y), 
Na (
y), and 
Na (
h), showing that it can comprehensively estimate their production cross sections.
Yee-Rendon, B.; Kondo, Yasuhiro; Tamura, Jun; Meigo, Shinichiro; Maekawa, Fujio
JPS Conference Proceedings (Internet), 45, p.011173_1 - 011173_7, 2026/06
The Japan Atomic Energy Agency (JAEA) is carrying out research and development on an Accelerator Driven Subcritical System (ADS) for nuclear transmutation. The JAEA-ADS consists of a CW superconducting proton linac of 30 MW coupling with a subcritical core reactor. The linac will accelerate a 20-mA proton beam to a final energy of 1.5 GeV, starting with a Normal Conducting section up to 2.5 MeV, and followed by a Superconducting part. More than 300 LLRF systems will control longitudinal parameters of the RF structures that compose the linac. In addition to ensuring stability on RF settings for efficient linac performance, the JAEA-ADS LLRF system will also enable fault-tolerance compensations to increase the availability of the linac, which is a major challenge for ADS operation. In this work, we will discuss the necessity of the ADS LLRF and present a proposed model that satisfies these demands.
Yee-Rendon, B.; Kondo, Yasuhiro; Tamura, Jun; Meigo, Shinichiro; Maekawa, Fujio
JPS Conference Proceedings (Internet), 45, p.011174_1 - 011174_10, 2026/06
A 30 MW continuous wave proton linac is devised by the Japan Atomic Energy Agency (JAEA) for the use of Accelerator Driven Subcritical System (ADS) technology. The efficiency of the accelerator is crucial for the realization of ADS in terms of minor actinides management. Therefore, it is necessary to assess the overall efficiency of the different components to ensure the accelerator's feasibility. This study estimated the power required to operate RF cavities, considering effects such as beam loading and microphonics. Additionally, the contribution of cryogenics was considered by calculating the heat load generated by the cryomodules, as well as the power consumption of auxiliary systems such as magnets. In this analysis, we will present the efficiency estimations of the JAEA-ADS linac, as well as the methodology used to obtain the results.
Adachi, Kyosuke; Tamura, Fumihiko; Nomura, Masahiro; Shimada, Taihei; Miyakoshi, Ryosuke*; Okita, Hidefumi; Yoshii, Masahito*; Omori, Chihiro*; Seiya, Kiyomi*; Hara, Keigo*; et al.
JPS Conference Proceedings (Internet), 45, p.011121_1 - 011121_8, 2026/06
no abstracts in English
beam in J-PARCHarada, Hiroyuki; Saha, P. K.; Yoneda, Hitoki*; Michine, Yurina*; Onoda, Genki*; Yamada, Ippei; Shibata, Takanori*; Sato, Atsushi*; Kinsho, Michikazu
JPS Conference Proceedings (Internet), 45, p.011133_1 - 011133_8, 2026/06
In high-intensity proton accelerators, negative hydrogen ions are charge-exchanged to protons by a carbon foil installed at the injection point of a ring accelerator. While this injection method can produce a high-intensity proton beam, it is a destructive method in which beams are passed through the foil, which leads to a short lifetime of the foil itself and to high radiation of the injection devices. Therefore, we proposed a non-destructive laser stripping injection scheme and develop for laser stripping experiment. In this study, a long-distance laser optical path of 70 m was newly constructed for the experiment. In this presentation, an overview of the laser stripping injection will be presented and the construction of the optical path, which is important for the execution of this experiment, will be reported. In addition, future experimental plans and prospects will be discussed.
Shinto, Katsuhiro; Okoshi, Kiyonori; Shibata, Takanori*; Nammo, Kesao*; Kawai, Isao*; Ikegami, Kiyoshi*; Takagi, Akira*; Asano, Hiroyuki*; Ueno, Akira; Oguri, Hidetomo
JPS Conference Proceedings (Internet), 45, p.011137_1 - 011137_10, 2026/06
In the autumn of 2014, we initiated the operation of a cesiated radio frequency (RF)-driven negative hydrogen (H) ion source at J-PARC in response to the necessity for increased beam intensities in the experimental facilities. The RF-driven ion source has extracted H beams with a beam energy of 50 keV and a beam current of 33 mA at the outset, 47 mA since January 2016, and 60 mA since October 2018. The last value fulfills the requirement that the linac injects the H beams with a beam current of 50 mA as specified in the initial design value into the 3-GeV rapid-cycling synchrotron (RCS). Prior to the 2021/2022 campaign, the ion source had been exchanged on one to three occasions during a campaign. Because it was challenging to ascertain the operational longevity that the RF-driven ion source could deliver beams without any significant issues necessitating the suspension of operations. However, from the 2022/2023 campaign onwards, a single RF-driven H ion source has functioned to deliver the H beams, with the continuous operation time exceeding 4,400 hours. Over the course of this decade, three instances of antenna failure and several other issues have been encountered. This presentation provides the statistical data pertaining to the RF-driven H ion source in terms of user operations, along with an overview of the R&D status in relation to the future J-PARC upgrades.
Shobuda, Yoshihiro; Togashi, Tomohito
JPS Conference Proceedings (Internet), 45, p.011160_1 - 011160_9, 2026/06
no abstracts in English
ion sourceShibata, Takanori*; Shinto, Katsuhiro; Nammo, Kesao*; Okoshi, Kiyonori; Kawai, Isao*; Ikegami, Kiyoshi*; Oguri, Hidetomo
JPS Conference Proceedings (Internet), 45, p.011155_1 - 011155_10, 2026/06
Saito, Shigeru; Meigo, Shinichiro; Makimura, Shunsuke*; Hirano, Yukinori*; Tsutsumi, Kazuyoshi*; Maekawa, Fujio
JPS Conference Proceedings (Internet), 45, p.011177_1 - 011177_9, 2026/06
A proton irradiation facility is under consideration at J-PARC to study the irradiation effects of candidate structural materials for accelerator-driven systems (ADS) and high-power target materials. In the facility, irradiation tests in liquid lead-bismuth eutectic (LBE) alloys will be performed for the candidate structural materials. Post irradiation examination (PIE) of irradiated samples will be carried out in the PIE facility to be constructed near the proton irradiation facility. In the PIE facility, PIE of the samples irradiated in the other facilities in J-PARC and in overseas accelerator facilities will also be performed. In this presentation, first, the conceptual study of the PIE facility, including the items to be tested and the test flow will be described. And then, the specifications and quantities of the facilities and the test equipment required to perform these test items will be shown. Finally, the layout of the PIE facility will be proposed.
Oikawa, Kenichi; Matsumoto, Yoshihiro*; Sato, Hirotaka*; Watanabe, Kenichi*; Parker, J. D.*; Shinohara, Takenao; Kiyanagi, Yoshiaki*
JPS Conference Proceedings (Internet), 45, p.011047_1 - 011047_8, 2026/06
Takei, Hayanori
JPS Conference Proceedings (Internet), 45, p.011175_1 - 011175_7, 2026/06
The Japan Atomic Energy Agency is working on the research and development of an accelerator-driven nuclear transmutation system (ADS) for transmuting minor actinides. This system is a combination of a subcritical nuclear reactor and a high-power superconducting proton linear accelerator (JADS-linac). One of the challenges in developing the JADS-linac is to reduce the number of beam trips. Until now, the beam trip frequency of the JADS-linac has been estimated from the operation data of the J-PARC linac, which uses the normal-conducting acceleration (NC) cavities. Recently, data on beam trips in the superconducting acceleration (SRF) cavities of the Spallation Neutron Source of the Oak Ridge National Laboratory (SNS) have been published. These data are important for the estimation of the beam trip frequency of the JADS-linac. Rather, the SNS data are more appropriate than the J-PARC data, because the JADS-linac uses the SRF cavities. On the other hand, the calculation methods in the published data for the NC cavities of J-PARC and the SRF cavities of SNS are different, so it is not possible to simply compare the two. In this study, the mean time between beam trips (MTBT) of the J-PARC NC cavity and the SNS SRF cavity are compared using the same condition. Specifically, the MTBT of the acceleration cavities connected to a single klystron system was calculated and compared. As a result, the MTBT of the SNS SRF cavity was 5.0 and 8.8 times longer than that of the J-PARC NC cavity for 
and 
h, respectively, where 
is the beam trip duration.
