New Aps Storage Ring Bpm Timing System Design *

A new beam position monitor (BPM) timing system has been designed for the Advanced Photon Source (APS) storage-ring. The old system used beam-derived triggers. The timing system provided a gate to determine which stored bunch would be processed. While this system served the APS well, it was determined that an rf-derived trigger system would reduce unwanted effects such as measured position intensity dependence. The new BPM timing system provides independently settable rf-derived timing triggers for each BPM. The system uses an existing module design to provide rf-derived triggers for each stored bunch in conjunction with a new module design that selects rf-derived triggers and provides independent delays for each BPM within a sector. The system provides the flexibility to trigger on single or multiple bunches per turn and supports arbitrary trigger patterns of up to 400 turns in length. The design and performance of this new system are discussed.