Annual Report 2025

The RCNP Annual Report 2025, summarizing our activities in FY2025, is now available.

This year, RCNP has continued to advance nuclear physics and its interdisciplinary applications through a broad range of experimental, theoretical, and technological research. As an international joint-use and joint-research center, RCNP provides unique accelerator and quantum-beam capabilities while serving as a hub for collaboration among researchers from Japan and abroad.

The highlights presented in this volume illustrate the breadth of our scientific activities, from the fundamental properties of nuclear and hadronic matter to the development of advanced experimental infrastructure and applications of quantum beams.

One important achievement was the progress in understanding nuclear matter under the extreme conditions realized in core-collapse supernovae. Large-scale simulations clarified how the equation of state of hot and dense nuclear matter influences collapse dynamics, proto-neutron-star evolution, and neutrino emission, strengthening the connection between microscopic nuclear physics and macroscopic astrophysical phenomena.

In theoretical hadron physics, studies of finite-length flux tubes using the dual Ginzburg-Landau theory advanced our understanding of the nonperturbative QCD vacuum and quark confinement mechanisms.

Significant progress was also achieved in experimental infrastructure. The upgrade design of the Large Acceptance Spectrometer was refined through ion-optics and Monte Carlo simulations, providing a basis for future high-resolution experiments.

In addition, advancements in laser isotope separation for calcium-48 were made. Since enriched ⁴⁸Ca is essential for neutrinoless double beta decay searches, these developments represent an important step toward practical production.

At LEPS2/BGOegg, studies of the in-medium mass spectrum of the η′ meson provided new experimental insights into modifications of hadron properties in nuclear matter, closely related to chiral symmetry and the QCD vacuum.

Muon science continued to expand, with precise measurements of nuclear charge radii using muonic X-ray spectroscopy. This work demonstrated the effectiveness of muonic atoms as probes of nuclear structure.

The ONOKORO project also made substantial progress in the systematic study of nuclear clustering through proton-induced knockout reactions, establishing both experimental and theoretical frameworks for a wide range of nuclei.

These achievements highlight the strong integration of experimental and theoretical research at RCNP, spanning nuclear physics, hadron physics, astrophysics, muon science, and interdisciplinary applications.

I would like to express my sincere gratitude to all members, collaborators, and supporting organizations. RCNP continues to evolve as a hub for quantum beam science and international research, and we look forward to further advancements in the coming years.

Sincerely yours,

Takashi Nakano
Director of Research Center for Nuclear Physics