The Advanced Photon Source Injection Timing System*

F. Lenkszus, R. Laird
Argonne National Laboratory


The Advanced Photon Source consists of five accelerators. The injection timing system provides the signals required to cause a bunch emitted from the electron gun to navigate through intermediate accelerators to a specific bucket (1 out of 1296) within the storage ring. Two linacs and a positron accumulator ring operate at 60Hz while a booster synchrotron ramps and injects into the storage ring at 2Hz. The injection timing system is distributed, modular VME/VXI-based, controlled by 2 EPICS-based IOCs (I/O controllers). Over 40 VME/VXI cards have been developed to implement the system. Card types range from 352MHz VXI timing modules to VME-based fiber optic fanouts and logic translators/drivers. All timing is distributed with fiber optics. Timing references are derived directly from machine low-level rf of 9.77MHz and 352MHz. The timing references provide triggers to programmable delay generators. Three grades of timing are provided. Precision timing is derived from commercial digital delay generators. VXI 8-channel digital delay generators provide timing with 25ns peak-to-peak jitter. Modest precision timing is provided by the APS event system. The timing system is fully integrated into the APS EPICS-based control system.