Timing system at ess

The European Spallation Source (ESS) timing system is based on the hardware developed by Micro-Research Finland (MRF). The main purposes of the timing system are: generation and distribution of synchronous clock signals and trigger events to the facility, providing a time base so that data from different systems can be time-correlated and synchronous transmission of beam-related data for for different subsystems of the facility. The timing system has a tree topology: one Event Generator (EVG) sends the events, clocks and data to an array of Event Receivers (EVRs) through an optical distribution layer (fan-out modules). The event clock frequency for ESS will be 88.0525MHz, divided down from the bunch frequency of 352.21MHz. An integer number of ticks of this clock will define the beam macro pulse full length, around 2.86ms, with a repetition rate of 14Hz. An active delay compensation mechanism will provide stability against long-term drifts. A novelty of ESS compared to other facilities is the use of the features provided by EVRs in μTCA form factor, such as trigger and clock distribution over the backplane. These EVRs are already being deployed in some systems and test stands.