The CMS trigger system

Understand

This paper describes the CMS trigger system and its performance during Run 1 of the LHC.

• The trigger system consists of two levels designed to select events of potential physics interest from a GHz (MHz) interaction rate of proton-proton (heavy ion) collisions.
• The first level of the trigger is implemented in hardware, and selects events containing detector signals consistent with an electron, photon, muon, tau lepton, jet, or missing transverse energy.
• A programmable menu of up to 128 object-based algorithms is used to select events for subsequent processing.