Open source event timing system at ALS-U

The Advanced Light Source Upgrade (ALS-U) is a major upgrade project for the existing light source at Lawrence Berkeley National Laboratory. One of the key challenges of the upgrade is that the new accelerator sections cannot operate at the existing RF frequency. The injector will operate at the current RF frequency (f1 = 499.64MHz) and the new Accumulator Ring and Storage Ring will operate at a rationally related frequency (f2 = p/q * f1 = 500.39MHz). As a result, the Timing Event Generator (EVG) must be synchronous to both RF frequencies and generate separate event streams for each frequency domain. To support beam transfer from the injector (f1) to the Accumulator Ring (f2), the EVG must detect the coincidence of the two frequencies and synchronize counters to the coincidence rate.. Due to extensive need for timing channels, Event Fanout (EVF) and Event Receiver (EVR) chassis were also designed as part of this effort. This paper describes the main concepts of the Dual EVG, EVF and EVR projects, open source gateware, embedded software and EPICS IOC implementations, as well as the tests and deployment at the current ALS.