Beam commissioning and operation of the J-PARC main ring synchrotron

The slow cycling main ring synchrotron (MR) is located the furthest downstream in the J-PARC accelerator cascade. It became available for user operation in 2009 and provides high-intensity 30 GeV proton beams for various experiments on particle and nuclear physics. The MR has two beam extraction systems: a fast extraction system for beam delivery to the neutrino beam line of the Tokai-to-Kamioka (T2K) experiment and a slow extraction system for beam delivery to the hadron experimental hall. After a nine-month beam shutdown during the recovery from the Great East Japan Earthquake, the J-PARC facility resumed beam operation in December 2011. The MR delivers a 160–200 kW beam to the T2K experiment and a 3.5–6 kW beam to users in the hadron experimental hall. In this paper, a brief review of the MR and the recent status of beam operation are presented. Near-future plans for a beam intensity upgrade are also discussed.