PRESENT STATUS AND FUTURE PLAN OF COMPACT SR RING HiSOR

Hiroshima Synchrotron Radiation Center (HSRC) is a common facility for research and education in the field of synchrotron radiation science in Japan. The major role of the facility is to promote nationwide SR research activities in materials science, especially in solid state physics, and education in the related fields simultaneously. HiSOR is a compact synchrotron radiation source of HSRC constructed in 1996 as a typical VUV — soft X-ray source (0.87 keV critical photon energy) similar to Helios in Singapore. Because of a compact racetrack-type ring, its natural emittance 400π nm · rad is not so small as the other standard-sized rings. There are two undulators, one linear for 26–300 eV range and the other helical/linear for 4–40 eV. The most outstanding feature of the facility lies in the good combination with beamlines to attain high-resolution (below 1 meV) for photoemission spectroscopy. It is routinely operated from 09:00 to 20:00 on weekdays at the stored current starting from 350 mA with 8 h lifetime at 300 mA. HiSOR has been running over 10 years, thus, it is time to think about the future improvements of the facility. The motivation is to pursue the leading position in the field of materials science (solid state physics) using SR for high-resolution photoemission spectroscopy. Some candidates for the upgraded HiSOR are presented.