High intensity measurement issues at the J-PARC RCS

The J-PARC Rapid-Cycling Synchrotron (RCS) is designed as a 1-MW high intensity proton accelerator. Beam intensity diagnostics is an important means of inspecting the accelerator performance. The RCS has two beam intensity monitors based on different principles; the DC Current Transformer (DCCT) and Slow Current Transformer (SCT). The SCT showed a strange behavior when a continuous 1-MW demonstration was performed, however, there was no problem under 1-MW equivalent operation with a single shot. The problem was deeply investigated via the test pulse and circuit simulation. On the other hand, the DCCT also showed output signal saturation with a 1.13-MW equivalent single shot, whereas, the SCT functioned properly under the same condition. There is a need to reveal these problems for future continuous 1-MW and higher intensity operation. In this paper, we will show a beam and test pulse data and discuss about how to measure these problems. (author)