Data collection modules for the PHENIX experiment

The data acquisition (DAQ) system for the PHENIX experiment is designed as a pipeline system with simultaneous triggering and readout. The maximum average level-1 (LVL1) trigger rate is 25 kHz. The DAQ system consists of Front-End Modules (FEMs), a level-1 (LVL1) trigger, data collection modules (DCMs), timing systems, slow controllers and an event builder (EVE). The data collection modules have the responsibility of collecting uncompressed LVL1 trigger event fragments from the FEMs. The DCMs provide buffering for up to five LVL1 events. The DCMs also perform zero suppression, error checking, data reformatting and outputting data to the event builder. In addition to the FEM data, the DCMs also receive primitives from LVL1 trigger system. These primitives are used for alignment checking on the FEM data packet. Additional trigger primitives can also be generated together with the FEM Data. The DCM is hosted in a VME crate. VME is used as a means for maintenance and slow control. Data collection within the crate is done through a private data-way.