KEK and its plans

Abstract

There are two campuses in KEK, Tsukuba and Tokai. In the Tsukuba campus, the operation of the SuperKEKB accelerator just started with the full Belle II detector from March 2019. SuperKEKB and Belle II had been upgraded from KEKB and Belle, respectively. The luminosity exceeded 1.6× 1034 cm−1s−1 in April 2020 with lower total beam current as compared with KEKB due to smaller vertical focussing length at the interaction point (βy*). It indicates that the upgrade accelerator can provide higher luminosity with higher beam current in the near future after sufficient vacuum scrubbing. The Belle II detector is basically working well. The time-depenednt B0−B̄0 mixing was clearly demonstrated as an example. In the Tokai campus, the high intensity proton accelerator (J-PARC) has been operated for more than 10 years. The facility provides us various particle beams (pion, kaon, neutron, muon and neutrino). Several nuclear experiments have been carried out using pion and kaon beams. The T2K experiment provides some results for the CP-violation in the neutrino sector using neutrino and antineutrino beams. New project, Hyper-Kamiokande (HK) was officially approved in January 2020. The detector and the beam line for the COMET experiment (the search for the charged lepton flavor violation) have been constructed steadly to aim the run start in 2023. The material and other sciences have been performed utilizing neutron and muon beams.