THE BPM DAQ SYSTEM UPGRADE FOR SUPERKEKB INJECTOR LINAC

The KEK electron/positron linac is a 600-m-long injector that provides the beams with different energy to four independent storage rings. The non-destructive beam position monitor (BPM) is an indispensable diagnostic tool for a long-term stable beam operation. In the KEK linac, about one hundred BPMs with the four strip-line type electrodes are utilized for the beam orbit and charge measurement. The measured beam orbit data is used for the beam orbit and energy feedback loops. The current data acquisition (DAQ) system for BPM comprises 24 fast digital oscilloscopes. They can work as a WindowsXP-based EPICS IOC. Toward the SuperKEKB project, the upgrade of injector linac is going on for increasing the beam intensity and reducing the emittance. For the SuperKEKB injector linac, the electron beam emittance will be reduced one-fifth smaller than that of former KEKB project by using a new RF gun. For this reason, the measurement precision of BPM is strongly required to be increased. In this paper, we present the upgrade plan and status of DAQ system for BPM towards SuperKEKB project in detail.