Performance of the CMS Level-1 Trigger during Commissioning with Cosmic Ray Muons

Understand

The CMS Level-1 trigger was used to select cosmic ray muons and LHC beam events during data-taking runs in 2008, and to estimate the level of detector noise.

• This paper describes the trigger components used, the algorithms that were executed, and the trigger synchronisation.
• Using data from extended cosmic ray runs, the muon, electron/photon, and jet triggers have been validated, and their performance evaluated.
• Efficiencies were found to be high, resolutions were found to be good, and rates as expected.