Track-based alignment of the ATLAS inner detector

Abstract

ATLAS is a general purpose experiment currently under final assembly for the Large Hadron Collider at CERN. The Inner Detector is the ATLAS internal tracker. It comprises different complementary technologies for tracking purposes: silicon and straw tubes gaseous detectors. In order to reach the optimal performance of the tracker, a high-precision alignment of the huge number of detecting elements is required. Several track-based alignment algorithms have been developed for the Inner Detector. An extensive validation has been performed with simulated events and real data coming from the ATLAS Combined Testbeam and data-taking of cosmic rays on surface. This paper reports on the principle of the different methods, computing requirements and results obtained with real data. Finally, preliminary results from the ATLAS Computing System Commissioning and Calibration Data Challenge are shown.