Track based alignment of the ATLAS Inner Detector

Abstract

The ATLAS Experiment is one of the four detectors located at the Large Hadron Collider at CERN in Geneva, Switzerland. It is a multi-purpose detector that will study high-energy particle collisions and which main aim is the Higgs boson discovery. The reconstruction of charged particle tracks and their decay vertices is performed by a sohisticated tracking system based on silicon sensors and drift tubes called Inner Detector. In order not to degenerate the track measurements, the position of the silicon detector elements has to be known to a precision better than about 10 µm. This precision can be achieved thanks to track-based alignment algorithms combined with measurements from hardware based alignment techniques. The proposed alignment algorithms for the ATLAS Inner Detector and their implementation into the common ATLAS software framework are presented as well as the alignment strategy. Moreover, alignment results from testbeams, MonteCarlo simulations and real cosmic rays data are shown and discussed. Finally this note will also emphasize the importance of global distortions, so-called weak modes. 17th International Workshop on Vertex detectors