The CMS Silicon Tracker Alignment

The alignment of the Strip and Pixel Tracker of the Compact Muon Solenoid experiment, with its large number of independent silicon sensors and its excellent spatial resolution, is a complex and challenging task. Besides high precision mounting, survey measurements and the Laser Alignment System, track-based alignment is needed to reach the envisaged precision. Three different algorithms for track-based alignment were successfully tested on a sample of cosmic-ray data collected at the Tracker Integration Facility, where 15% of the Tracker was tested. These results, together with those coming from the CMS global run, will provide the basis for the full-scale alignment of the Tracker, which will be carried out with the first p-p collisions.