Beam intensity monitor using digital processing for a rapid-cycling proton synchrotron

Hayashi, Naoki  ; Yoshimoto, Masahiro  

A beam intensity monitor is one of the most fundamental diagnostics for an accelerator. For a high duty rapid-cycling synchrotron, such intensity monitor must have very long time constant and the circulating beam current must be divided by revolution velocity in order to determine the intensity. It is realized by analogue circuit. The J-PARC Rapid-Cycling Synchrotron (RCS) is equipped two instruments, namely DCCT (DC Current Transformer) and SCT (Slow-CT). Recently, the beam intensity approaches to the designed value, the present intensity monitor sometimes shows overroad behavior with certain beam conditions. Although Medium-CT (MCT), which main purpose is to monitor the intensity during injection period, has its time constant about 2 seconds, it can be used as a backup instrument for DCCT or SCT with digital signal processing.