Track reconstruction of cosmic ray real data with the CMS Silicon Strip Tracker

The CMS tracking system consists of a silicon pixel vertex detector and a surrounding silicon microstrip detector. The system is currently going through final assembly stage. As the construction goes on, big parts of the detector are being powered, controlled and readout as a whole. A cosmic ray trigger has been setup, thus providing the first real events recorded in the CMS tracker. Reconstruction was performed with three track finder algorithms: we will talk about the Combinatorial Track Finder, which is based on the Kalman Filter technique for both trajectory building and track fitting. A dedicated algorithm for cosmic ray track's seeding has been developed, together with useful tools for the tracking performance analysis; the exercise has been very useful for the understanding and the improvement of the tracking algorithm. (C) 2008 Elsevier B.V. All rights reserved.