A First Level Calorimeter Trigger Processor for the Large Hadron Collider

As part of an R&D; project to study first-level calorimeter triggers for the LHC, a preliminary design of a bit-parallel digital trigger processor system is presented in this note. The trigger processor will process 4096 electromagnetic and 4096 hadronic trigger cells, selecting events on the basis of high-transverse-momentum electrons, jets and missing transverse energy. The results of the first-level trigger processor will be sent on to the central trigger processor and to the region-of-interest builder for use in the second-level trigger; the information will also be available for monitoring and off-line evaluation.