A 40 GByte/s read-out system for large collider detectors

We present the design of a read-out system for a large collider detector. The readout was designed for GEM, one of the two detectors that was planned for the Superconducting Super Collider. However, given the similarity in requirements, the design may be relevant for other proton collider detectors. The readout is designed to cope with the huge number of channels and enormous data rates, typical for high luminosity colliders. To simplify front-end design, the system reads all digitized data from the detector data sources at the full Level 1 trigger rate of up to 100 kHz. A total read-out bandwidth of 40 Gbytes/s is available. Data are stored in buffers that are accessible for further event filtering by an on-line processor farm. Data are transported to the farm only as they are needed by the higher-level trigger algorithms, leading to a reduced bandwidth requirement in the data acquisition system.