Alignment of the Muon Spectrometer in ATLAS

The ATLAS muon spectrometer is designed to measure the momentum of a 1 TeV/c muon to an accuracy of 10%. A muon of this momentum bends, on average, 500 μm in the toroidal field of ATLAS. Therefore, the position of the muon chambers within a tower and along the precision coordinate must be known to better than 50 μm. ATLAS uses a combination of an optical and track-based alignment to achieve such a precise alignment. Several analyses to monitor and validate the alignment were undertaken in the first year of LHC operation. This report provides a brief overview of the motivation, building and commissioning of the optical system, performance, and validation of the alignment of the muon spectrometer.