Performances of the CMS Tracker

With a total area of almost 200 square meters, about 15000 silicon modules, and nearly 10 million readout channels, the CMS Silicon Strip Tracker is by far the largest silicon strip detector ever built. Inside the Strip Tracker, a Pixel Detector made of three barrel layers closed by two forward/backward disks on each side of the interaction region, provides a crucial contribution to pattern recognition, as well as primary and secondary vertices reconstruction. Altogether the Tracker reconstructs the trajectories of charged particles, measures their momentum, and plays a major role in lepton identification and heavy quark tagging. The strip detector has been integrated and commissioned in a dedicated assembly hall on the surface, then inserted in CMS, and re-commissioned using cosmic triggers from the CMS muon system. Excellent results have been achieved in terms of detector performance and preliminary alignment results. The pixel barrel and forward detectors have been built and commissioned separately, and then integrated in CMS. Re-commissioning with the rest of the detector has been done with cosmic triggers.