The 50th Anniversary of KEK and the 40th Anniversary of KENS

Abstract

KEK, High Energy Accelerator Research Organization, hold “The KEK 50 th Anniversary Ceremony and KEK 50 th Anniversary Symposium” from November 8 to 10, 2021. KEK was established in 1971 as the first Inter-University Research Institute in Japan. The main purpose of KEK was to construct and utilize large accelerator for high energy physics, but later, it extended scientific fields to materials and life sciences. The KENS neutron scattering facility was established in 1978 as a division of the Booster Synchrotron Utilization Facility (BSF) in KEK, and the first users’ research program using a pulsed spallation neutron source dedicated to material sciences started in 1980. Before KENS, scientists exploited electron linear accelerators as pulsed neutron sources for slowneutron scattering applications, including numerous types of time-offlight-based instruments. Prominent among these was the Tohoku Linac neutron source of Motoharu Kimura and his colleagues in the 1960s, where Noboru Watanabe cut his scientific teeth. Kazuhiko Inoue’s Electron Linac at Hokkaido University contributed to developing neutron moderators. Following the pioneering works on proton accelerator spallation neutron source in ANL, four facilities, KENS, ANL, LANL, and IPNS, with thermal and cold neutron sources at proton accelerator were constructed around 1980. The final check for KENS cold source on 500 MeV proton beam was finished in 1978. The first practical pulsed spallation neutron beam was introduced in June 1980, and all the information was delivered to the international neutron community soon through ICANS. In 1980, the proton beam power of KENS was only 1 kW, but upgraded to 5 kW in 1985 as well as neutron target was converted from tungsten to depleted uranium. KENS operated 13 instruments until 2004 and developed neutron technologies and grow many users as well as various kinds of scientific achievements. Based on the success of KENS, J-PARC project was approved and MLF has been constructed as one of the most intense spallation neutron facilities in the world. Thus, we would like to stress that 2020 was extremely important for the neutron community as the 40 th anniversary of KENS in the 50 years history of KEK. For this reason, the Institute of Materials Structure Science in KEK held an online symposium to celebrate the 40 th anniversary of spallation neutron and muon in Meeting Report