Worker dose under high-power operation of the J-PARC 3 GeV Rapid Cycling Synchrotron

Yamamoto, Kazami   

The J-PARC 3 GeV Rapid Cycling Synchrotron (RCS) delivers a 1-MW, high-intensity beam to the following facilities. In such high-intensity accelerator, the operational beam intensity is limited to keep the exposure to the workers by the residual dose within acceptable tolerances. Therefore we continue to commission the accelerator system to reduce the beam loss. In order to achieve further high-intensity operation, the J-PARC accelerator system was drastically upgraded (Increment of the injection energy of RCS and peak current of Linac) over the past two years. After the upgrade, the beam loss was decreased by the commissioning. The output power was increased; nevertheless the residual doses were kept same level or decreased. Since we replaced the broken collimator which was higher activated, we kept the exposure to the workers within acceptable level.