The level-1 calorimeter trigger for the CMS detector at LHC

The level-1 calorimeter trigger system for the CMS detector at LHC collider provides a deadtimeless pipelined trigger that implements simple algorithms which satisfy the physics efficiency and data rate requirements. We plan to run the trigger system at 160 MHz in order to provide a compact system by quadrupling the use of most components and data paths within an LHC crossing of 40 MHz. Many logic elements in the design are implemented in custom integrated circuits with much attention paid to the trigger data optimization and the latency in processing. Through extensive simulation of the level-1 calorimeter trigger, we have determined the background rates and efficiencies for various triggers such as those for electrons, photons, jets and neutrinos.