Alignment of the ATLAS Inner Detector Tracking System

Abstract

The ATLAS Experiment is equipped with a charge particle tracking system built on three sub-detectors: silicon pixels, silicon strips and straw tubes, composing the ATLAS Inner Detector (ID) which is embeded in a 2 Tesla magnetic field. To achieve the desired tracking performance, these sub-detectors have to be aligned with the typical precision better than 10 micrometers. Different alignment techniques have been used to reconstruct the detector geometry. Cosmics data collected between 2008 to 2009 and 900 GeV center-of-mass energy proton-proton collision data collected in December 2009 are used simultaneously to derive alignment constants. The performance of the alignment is also studied using 7 TeV collision data collected in May 2010. The results show that the ATLAS tracker is approaching the precision of ideal geometry.