The central component of the CMS detector is the largest silicon tracker ever built. The precise alignment of this complex device is a formidable challenge, and only achievable with a significant extension of the technologies routinely used for tracking detectors in the past. This article describes the full-scale alignment procedure as it is used during LHC operations. Among the specific features of the method are the simultaneous determination of up to 200 000 alignment parameters with tracks, the measurement of individual sensor curvature parameters, the control of systematic misalignment effects, and the implementation of the whole procedure in a multiprocessor environment for high execution speed. Overall, the achieved statistical accuracy on the module alignment is found to be significantly better than 10 µm.

am P.C. Bhat, am K. Burkett, am S. Cihangir, am O. Gutsche, am H. Jensen, am M. Johnson, am N. Luzhetskiy, am D. Mason, am T. Miao, am S. Moccia, am C. Noeding, am A. Ronzhin, am E. Skup, am W.J. Spalding, am L. Spiegel, am S. Tkaczyk, am F. Yumiceva, am A. Zatserklyaniy, am E. Zerev, am I. Anghel, an V.

No abstract

During summer 2006 a fraction of the CMS silicon strip tracker was operated in a comprehensive slice test called the Magnet Test and Cosmic Challenge (MTCC). At the MTCC, cosmic rays detected in the muon chambers were used to trigger the readout of all CMS subdetectors in the general data acquisition system and in the presence of the 4 T magnetic field produced by the CMS superconducting solenoid. This document describes the operation of the Tracker hardware and software prior, during and after data taking. The performance of the detector as resulting from the MTCC data analysis is also presented.

No abstract