Upgrade of the Beam Position Monitoring System at the J-PARC Main Ring for High Intensity Operation

For the T2K neutrino oscillation experiment upgrade programs of J-PARC are on-going for higher beam intensity. The ultimate goal is to achieve a beam power of 1.3 MW in the main ring, a significant increase more than triple intensity compared to the presently achieved power of 470 kW. Beam loss is a cause of the limitation on the proton bunch intensity. A precise orbit correction is necessary in order to reduce the beam loss. Beam position monitor (BPM) is a vital element providing accurate measurements of the beam positions for the control of closed orbit distortion (COD). Currently an apparent dependence of COD RMS on the beam intensity is observed (about 30 μ m). In order to understand the nature of the phenomenon, investigations are being made on the BPM response and its intensity dependence as well as on the effects of wake field, beam bumps to COD and septum. Status of the studies will be discussed. Also presented are new design of BPM for improved position resolution and stability, and its expected performance.
Proceedings of the 6th Int. Beam Instrumentation Conf., IBIC2017, Grand Rapids, MI, USA