UVSOR at Institute for Molecular Science Celebrating Its 50th Anniversary

Abstract

Institute for Molecular Science celebrated its 50th anniversary in April 2025. A synchrotron light source, UVSOR, was installed there in the early 1980s. It has been leading the synchrotron radiation science in Japan alongside the Photon Factory (KEK), which was built around the same time. UVSOR already passed its 40th anniversary two years ago. It has been supplying low-energy synchrotron light, covering the vacuum ultraviolet and soft X-ray regions as well as infrared and terahertz waves, to researchers in a wide range of fields both in Japan and overseas. It has undergone two major upgrades to address aging and improve performance. The emittance of the electron beam, which determines the brightness of the synchrotron light, has improved by approximately one order of magnitude from its original value. The number of undulators that can take advantage of this high brightness characteristic has been increased from the original two to six. Furthermore, top-up operation, which has become the standard operating method for modern synchrotron light sources, has also been introduced. Taking advantage of the unique features of a small, agile facility, UVSOR has produced many pioneering results in the development of various light source technologies, including free electron lasers, space-time structured light, and laser Compton scattering gamma-rays. However, the fight against aging and declining competitiveness is never-ending, and the time has come to aim for the realization of the next upgrade plan.