Alignment of the ATLAS Inner Detector Tracking System

In order to reconstruct trajectories of charged particles produced in the LHC collisions, ATLAS is equipped with a tracking system built using two different technologies, silicon planar sensors (pixel and microstrips) and drift-tube based detectors. Together they constitute the ATLAS Inner Detector, which is embedded in a 2 T solenoid field. In order to achieve required performance, an alignment of the ATLAS inner tracking system is required, to accurately determine the position and orientations of the detector modules. The ATLAS Inner Detector has been aligned using high pT, isolated collision tracks, and using cosmic-ray tracks collected between LHC proton-proton collisions. This poster presents the alignment procedure, its results, and performance with LHC collision data. Results from real data are compared with Monte Carlo simulation of a perfectly aligned detector.