Track-based alignment of the ATLAS Inner Detector: implementation and performance

Abstract

The Large Hadron Collider (LHC) at CERN is the world's largest particle accelerator. It collides proton beams at unprecedented centre-of-mass energies. ATLAS is a multipurpose experiment that records the products of the LHC collisions. In order to reconstruct the trajectories of charged particles produced in these collisions, ATLAS is equipped with a precision tracking system, the Inner Detector (ID). The ID alignment procedure ensures an accurate determination of the position and orientation of the detector's sensors, such that detector mis-alignments do not degrade the physics performance. An outline of the track-based alignment approaches, their implementation within the ATLAS software framework and the resulting performance is presented.