Global Event-identifier Module: A distributed digital approach to event-of-interest identification logic for physics experiments

The demands from current data acquisition systems are to acquire data from a large number of detectors (or signals) while providing a high throughput. This can be achieved by having some preprocessing capability in the data acquisition system so that it can identify the events of interest. Precise selection of events with minimal time for identification and preprocessing is an experimental challenge. To address this challenge, we have developed a ''Global Event-identifier Module'' (GEM) on the CAMAC platform, which can flexibly adapt to the experimental requirements and validate an event with minimal time. GEM is a single width CAMAC module capable of operating in a ''distributed'' data acquisition environment where multiple CAMAC crates (each with one GEM module) can be used to collect synchronized data from all the crates. Event-of-interest decision can be made on signals connected to different crates. Inter-GEM communication is via the ubiquitous ethernet (unshielded twisted pair, CAT5) cable. The event of interest is decided within 32 ns (excluding cable delay). Implementation is accomplished using field programmable gate array which enables greater flexibility for algorithm modifications and updates without hardware changes. GEM supports unified, distributed, and multi-strobe data acquisition, enabling higher throughput, with data collection from a large number of signals by selective reads of events of interest as determined by the experimenter while providing timestamped data of each event.