Performance of the ATLAS muon trigger in pp collisions at a centre-of-mass energy of 8 TeV

Given the harsh detector environment produced by collisions of high energy protons at the LHC, events with muons in the final state are an important signature for many physics analyses. The ATLAS experiment employs a multi-level trigger architecture that selects the events in three sequential steps of increasing complexity and accuracy. The Level 1 trigger is implemented with custom-built hardware to reduce the event rate from 40MHz to 75 kHz. Then the software-based higher level triggers refine the trigger decisions reducing the output rate down to the order of 100 Hz. We present the performance of the muon trigger evaluated with proton-proton collision data collected in year 2012 at a centre-of-mass energy of 8 TeV.