Real Time Bunch-by-Bunch Luminosity Monitor for BEPCII

We have designed and implemented a fast bunch-by-bunch luminosity monitor for BEPCII. Specially, the high speed electronics design fulfills the requirement to detect and record the event from one bunch pair within 4ns. In order to minimize the influence from very noisy environment of the collider, a couple of methods like discrimination, coincidence window and anti-coincidence techniques are adopted effectively. The preliminary experimental result shows that the hardware and software of the monitor system working well. From the result of the first operation in BEPCII collider, we can see that real time bunch by bunch monitor system will be very beneficial not only for monitoring the status of the collider machine but also for the stage of beam tuning.