Chinese Acad Sci, Inst High Energy Phys, Beijing 100039, Peoples R China
The beam position monitoring (BPM) system for the storage ring of the Beijing Electron Positron Collider (BEPC) has been upgraded. The short-term reproducibility of the measurement is better than 10 microns. The measurement time for scanning all BPMs is about 11 seconds. The dynamic rang of the system is over 81 dB and the minimum measurable beam intensity is less than 0.5mA. The reliability of the measurement is assured by the self-consistency check.