Research Institute for Synchrotron Radiation Science, Hiroshima University

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Outline of the Facility

General Information

　The Research Institute for Synchrotron Radiation Science (HiSOR), which has been reorganized from the Hiroshima Synchrotron Radiation Center in 2024, is a unique synchrotron facility attached to Hiroshima University in Japan. It was established in 1996, as part of the academic policies of the Japanese government. A compact 700 MeV electron-storage ring, HiSOR (the research institute is often referred to as HiSOR), produces synchrotron radiation in the vacuum ultraviolet (VUV) and soft X-ray (SX) range. These photon energies are suitable for studying electronic states in solids, such as energy-band dispersions, Fermi surfaces, spin polarization, and many-body interactions. In addition, circular dichroism in the VUV region is also useful for structural studies of biomolecules in solution. The mission of the research institute is to promote advanced research in the field of condensed matter physics using synchrotron radiation in the VUV and SX range, as well as to foster human resources as a facility affiliated in the university. Since 2010, the research institute has been authorized as a “Joint Usage / Research Center” by the Ministry of Education, Culture, Sports, Science and Technology (MEXT) and accepted many researchers and students not only from Japan but also from overseas.

Storage ring , beamlines and R&D

　The accelerator system at the research institute consists of a 150 MeV injector microtron, a beam transport line, and a racetrack-type 700 MeV electron-storage ring (HiSOR) with a circumference of 22 m. HiSOR has two 2.7 T normal-conducting bending magnets with a bending radius of 0.87 m providing a critical photon energy of 873 eV. There are 16 beam ports: 2 for undulator beamlines and 14 for bending magnet beamlines. We have constructed 15 beamlines in total, including 2 beam monitoring beamlines. On the two straight sections of HiSOR, we have installed a linear undulator and a variably polarizing undulator (APPLE-II type). We allocate approximately 1,500 hours for user beamtime annually. New instruments such as Laser spin ARPES, inverse ARPES, and thin film growth tools were being developed in the R&D hall adjacent to the experimental hall as part of the HiSOR upgrade plans.

Current Activities

　On the linear undulator beamline BL-1 (photon energy range: hν=22-300 eV), we have installed a unique rotatable angle-resolved photoemission spectroscopy (ARPES) system to investigate the symmetry of wave functions in solids, and fine electronic structures derived from the electron-phonon interaction near the Fermi level. On the variably polarizing undulator beamline, we have constructed two branch beamlines BL-9A (hν=5-35 eV) equipped with an ultrahigh resolution ARPES system and BL-9B (hν=16-300 eV) equipped with highly efficient spin- and angle-resolved photoemission spectroscopy (SARPES) system. BL-9A allows us to clarify the fine details of the electronic states on the meV energy scales in high-Tc cuprates or strongly correlated materials with high momentum and energy resolutions with variable photon energy. We have recently installed new focusing optics and analyzers to BL-1 and BL-9A which are very effective for the two-dimensional Fermi surface mapping of small samples. At BL-9B, one can investigate the three-dimensional spin structure of magnetic materials, as well as spin textures induced by the strong spin-orbit interaction in topological systems. BL-9B attracts many proposals, and over half of the beamtime is allocated to collaborators from outside of Japan. On beamline BL-12 (hν=2-10 eV), we have installed a vacuum ultraviolet circular dichroism (VUV-CD) spectrometer for the structural analysis of biomolecules (proteins, sugars, and nucleic acids) in solution. This experimental technique was developed at HiSOR and has been recognized as a powerful tool to clarify the structures of a wide range of samples under various solvent/environmental conditions. On beamline BL-14 (hν=400-1200 eV), one can fabricate atomically controlled thin films or nanostructures on substrates and perform soft X-ray magnetic circular dichroism (SXMCD) experiments to study their magnetic and electronic properties without exposing to the air. As part of our future plans, we are also working on designing a compact low-emittance electron storage ring called HiSOR-II.

Human resource development and outreach

　Affiliated with Hiroshima University, the research institute plays important roles in fostering human resources not only through lectures and seminars but also through research activities using synchrotron radiation. Furthermore, the research institute hosts the Hiroshima International Symposium on Synchrotron Radiation (HiSOR Symposium) every March. Distinguished researchers in our priority research areas are invited and give talks, while students present their scientific achievements in the poster session. To encourage students, we present the Best Poster Awards to those who demonstrate excellence in scientific research and presentation. We warmly invite visitors, including junior and senior high school students, as well as international students interested in STEAM. To further extend our outreach efforts, we have developed the ”VR Advanced Science Experience Seminar”, allowing students to explore our facility remotely. Through collaborations with the High Energy Accelerator Research Organization (KEK), National Institute of Technology (Hiroshima college and Kure college), and local museums, we are developing human resources in the fields related to accelerators, machine learning, virtual reality, and digital fabrication technologies.

History