The Particle Accelerator Society of Japan (PASJ) was established in 2004 and has grown significantly since then, leading accelerator research in Japan. While the number of members at the time of its establishment was 473, the current number is approximately 900. The doubling of the number of members over the past 20 years is a testament to the growth of the society. The PASJ has been operated as a voluntary organization, but on April 1, 2024, the 20th anniversary of its establishment, it became a general incorporated association. We would like to discuss the background behind the decision to incorporate, as well as the future of the PASJ as it moves forward as a general incorporated association.

In the recent J-PARC user operation from Nov. 10th, 2022 to June 22nd, 2023, continuous operation of 4,412 hours with hydrogen negative ion (H⁻ ion) beam current up to 60 mA was achieved by J-PARC radio frequency (RF) H⁻ ion source. This was also the first time to supply H⁻ ion beam to the Linac in the yearly J-PARC user operation term by a single ion source (w/o ion source exchange). To satisfy the requirements of the further upgrade in J-PARC, a soundness evaluation of the present ion source components has been performed. Furthermore, the RF ion source with a newly manufactured RF antenna coil has been under development.

A non-destructive beam profile monitor with a sheet-shaped gas has been developed. The gas sheet formed based on rarefied gas dynamics produces photons by interaction with a high intensity ion beam. The sheet shape enables a two-dimensional profile measurement by CCD camera capture of the photons. The beam profile can be obtained from the captured image through a reconstruction analysis with a response function of the monitor. The response function was measured by scanning of a thin electron beam on the monitor. The developed monitor was evaluated with the RFQ test stand consisting of J-PARC linac spares, and a 2-D high-intensity-beam profile was successfully reconstructed. The non-destructiveness of the developed monitor was also evaluated in terms of a beam current reduction and a beam phase space distribution change. The beam current reduction was in proportion to the injected gas flux, and the emittance decreased at high gas flux injection.

In recent years, short-lived radioisotopes (RIs) have been actively used and applied in a wide range of fields, not only in fundamental sciences such as physics and chemistry but also in biological fields for identifying the movement of elements within organisms and in medical fields such as cancer therapy and PET diagnosis.

On April 1, 2024, Research Center for Accelerator and Radioisotope Science (RARIS) Tohoku University has been established, which merges two internal research centers among Tohoku University with high short-lived RIs production capacity, i.e., the Research Center for Electron Photon Science and the Cyclotron and Radioisotope Center.

With the establishment of the Research Center for Accelerator and Radioisotope Science, a new research hub has been created for studies in nuclear physics, radiochemistry, nuclear medicine, radiopharmacology, and biomedical engineering using short-lived RIs. Furthermore, the unique characteristics and synergy between electron beams and ion beams will enable the development of new research grounded in short-lived RIs.

Laser-driven ion acceleration was discovered in 2000, and medical application projects using this acceleration method started in Japan the following year. Twenty years later, a prototype model of the laser-driven ion accelerator has been completed in 2023 at QST-Kansai. In this paper, we report on the results from medical application projects so far and present the data obtained during the commissioning of the prototype model.

Japan's collider experiments began with the TRISTAN project, which began operation in 1986. That was the moment when Japan leapt to the energy frontier of particle physics. On March 3, 2024 (Peach Festival), a workshop was held at the High Energy Accelerator Research Organization (KEK) in Tsukuba City, Japan, to reflect on this history and renew our vision for the future. The Super KEKB factory is still in operation, and efforts are underway for the International Linear Collider project and the subsequent domestic construction of muon collider. We need to reaffirm the horizon that TRISTAN has opened, and to make efforts to further raise that horizon.

To discover and foster the next generation of engineers and researchers in accelerator science, we are implementing an educational program where technical college students build accelerators by themselves. Activity members from each technical college gathered at Oyama National College of Technology for a debriefing session. This paper reports on the meeting.

The 6th Workshop on the Operation of Large Vacuum Systems (OLAV-VI) took place during 15–19 April 2024 at Fermilab in the USA. About 90 participants shared and discussed their vacuum system designs and operational experiences in particle accelerators, fusion research facilities, gravitational wave detectors, and vacuum related industries. Facility tours were organized to explore the latest scientific activities at Fermilab and the Argonne National Laboratory. At the end of the workshop, KEK and JAEA jointly proposed to host the next OLAV for 2027, where many participations from Japan will be highly welcomed to join lively discussions on the large vacuum systems.