A Machine leaning-based approach to estimate nuclide production cross sections

Iwamoto, Hiroki; Meigo, Shinichiro; Sugihara, Kenta*

JPS Conference Proceedings (Internet), 45, p.011179_1 - 011179_7, 2026/06

https://doi.org/10.7566/JPSCP.45.011179

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.

Power estimations for the JAEA-ADS linac

Yee-Rendon, B.; Kondo, Yasuhiro; Tamura, Jun; Meigo, Shinichiro; Maekawa, Fujio

JPS Conference Proceedings (Internet), 45, p.011174_1 - 011174_10, 2026/06

https://doi.org/10.7566/JPSCP.45.011174

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.

Spoke cavity prototyping for the JAEA-ADS Linac

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

https://doi.org/10.7566/JPSCP.45.011171

Cavity compensation studies in the JAEA-ADS superconducting linac using LightWin

Yee-Rendon, B.; Kondo, Yasuhiro; Tamura, Jun; Meigo, Shinichiro; Maekawa, Fujio; Plaais, A.*; Bouly, F.*

Proceedings of 22nd International Conference on RF Superconductivity (SRF2025) (Internet), p.316 - 320, 2026/04

High-intensity accelerators, particularly Accelerator-Driven Systems (ADS), require high availability and reliability for proper operation. For superconducting linear accelerators, the ability to continue operating even when one of the RF cavities fails is key to achieving the required availability, known as cavity compensation. Beam dynamics studies of the JAEA-ADS linear accelerator have demonstrated the possibility of operating with multiple RF cavities disabled with acceptable beam quality. Several other superconducting linear accelerator laboratories have adopted similar methods and developed their procedures. Among these efforts, the LightWin tool has proven to be an effective tool for automatically and systematically identifying compensation settings for each cavity failure in any linear accelerator. This software has been successfully utilized on the MINERVA linac, as well as on the high-energy part of the JAEA-ADS linac. It has currently been tested and improved to ease SPIRAL2 operation. This work presents an analysis of cavity compensation in the JAEA-ADS superconducting linear accelerator using the LightWin tool and compares the results with previous studies.

Beam dynamics studies of cavity failures for the initial operation phase of the ESS superconducting linac

Yee-Rendon, B.; Kondo, Yasuhiro; Tamura, Jun; Meigo, Shinichiro; Maekawa, Fujio; Miyamoto, Ryoichi*; Milas, N.*; Eshraqi, M.*

Proceedings of 22nd International Conference on RF Superconductivity (SRF2025) (Internet), p.58 - 62, 2026/04

The European Spallation Source (ESS) superconducting proton linac is currently undergoing commissioning. During the initial operation phase, the final beam energy will be about 800 MeV, reaching a 2 MW power. High reliability and availability are crucial for the success of the ESS science programs and thus operations will be maintained even with failures of main linac components such as cavities and quadrupoles, as long as ~50 percent of the intended power can be achieved. To this end, we developed beam optics strategies to address failures in the cavities of the superconducting linac. Due to the constraints in the RF cavity amplitudes, we implemented a modified version of standard cavity compensation techniques. The results indicated that this strategy enables beam recovery that meets the beam quality specifications, thereby enhancing the availability of the ESS linac.

Pulse bending magnet and septum magnet for 3-GeV proton beam transport line

Yamaguchi, Yuji; Kondo, Yasuhiro; Meigo, Shinichiro; Takayanagi, Tomohiro; Fujimori, Hiroshi*; Shinozaki, Shinichi

Proceedings of 22nd Annual Meeting of Particle Accelerator Society of Japan (Internet), p.655 - 660, 2026/03

https://www.pasj.jp/web_publish/pasj2025/proceedings/PDF/THP0/THP061.pdf

Preliminary designs of new bending magnets have been considered for the second target station (TS2) of Materials and Life Science Experimental Facility (MLF), J-PARC. To give a design approach for the bending magnets, several examples of bending magnets, such as a pulse bending magnet and a septum magnet were reviewed. The reviewed magnet specifications compared with requirements for the new bending magnets indicate that the new pulse bending magnet requires a new design idea, while the new septum magnet can be designed based on the previous design of an extraction septum magnet for the 3-GeV synchrotron in J-PARC. The new design idea for the pulse bending magnet and the septum magnet design idea based on the previous one are presented.

Conceptual study of J-PARC Proton Beam Irradiation Facility

Meigo, Shinichiro; Iwamoto, Hiroki; Sugihara, Kenta*; Hirano, Yukinori*; Tsutsumi, Kazuyoshi*; Saito, Shigeru; Maekawa, Fujio

JAEA-Technology 2024-026, 123 Pages, 2025/03

JAEA-Technology-2024-026.pdf:14.22MB

Based on the design of the ADS Target Test Facility (TEF-T) at the J-PARC Transmutation Experimental Facility, a conceptual study was conducted on the J-PARC proton beam irradiation facility. This research was carried out based on the recommendations of the Nuclear Transmutation Technology Evaluation Task Force of the MEXT. The recommendations state that it is desirable to consider facility specifications that can make the most of the benefits of using the existing J-PARC proton accelerator while also solving the engineering issues of the ADS. We considered facilities that could respond to a variety of needs while reducing the facilities that were not needed in the TEF-T design. In order to clarify these diverse needs, we investigated the usage status of representative accelerator facilities around the world. As a result, it became clear that the main purposes of these facilities were (1) Material irradiation, (2) Soft error testing of semiconductor devices using spallation neutrons, (3) Production of RI for medical use, and (4) Proton beam use, and we investigated the facilities necessary for these purposes. In considering the facility concept, we assumed a user community in 2022 and reflected user opinions in the facility design. This report summarizes the results of the conceptual study of the proton irradiation facility, various needs and responses to them, the roadmap for facility construction, and future issues.

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

J-PARC proton beam irradiation facility plan

Meigo, Shinichiro

Kasokuki, 21(4), p.333 - 344, 2025/01

https://doi.org/10.50868/pasj.21.4_333

For the study of material damage under the beam irradiation circumstance of accelerator-driven systems (ADS), the JAEA had planned to construct a TEF-T using J-PARC Linac 400-MeV proton beams and the LBE spallation target. The task force for evaluating partitioning and transmutation technology in the MEXT recommended that the facility be considered to maximize the advantages of using Linac to meet users' various needs. The proton irradiation facility, a successor of TEF-T, is planned to be constructed for 1) Material irradiation examinations, 2) Semiconductor soft-error examinations using spallation neutrons, 3) Medical RI production, and 4) Proton beam applications for space use. A user community was established in 2022 to incorporate user input as a more attractive facility. In this paper, the present design status of the facility is described.

Measurement of the spallation neutron spectrum by unfolding at 180 from 3-GeV protons and Hg with the Bi(n,xn) reactions

Sugihara, Kenta*; Meigo, Shinichiro; Iwamoto, Hiroki; Maekawa, Fujio

JAEA-Conf 2024-002, p.162 - 167, 2024/11

https://doi.org/10.11484/jaea-conf-2024-002

A neutron energy spectrum is important for shielding design at an Accelerator-Driven System facility (1.5-GeV p + Lead Bismuth Eutectic). A similar spectrum can be obtained at J-PARC (3-GeV proton + Hg). To check the validity of the unfolding, the unfolding with the Bi(n,xn) reactions and the response functions (JENDL/HE-2007 and TALYS) was applied. In our poster, we present the derivation of the spectrum and comparison with the spectrum with a Time-of-Flight technique.