The ATLAS Muon Trigger at High Luminosities

The ATLAS experiment at CERN's Large Hadron Collider (LHC) has taken data with colliding beams at instantaneous luminosities of $2cdot10^33 cm^-2 s^-1$. The LHC targets to deliver an integrated luminosity $5ifb$ in the run period 2011 at luminosities of up to $5cdot10^33 cm^-2 s^-1$, which requires dedicated strategies to guard the highest physics output while reducing effectively the event rate. The Muon High Level Trigger has successfully adapted to the changing environment of the low luminosity running of LHC in 2010 to the intensities encountered in 2011. The selection strategy has been optimized for the various physics analysis involving muons in the final state. This note reports about efficiency, resolution, and general performance of the muon trigger.