CMS Tracker upgrade issues and plans

The LHC accelerator complex will undergo a programme of consolidation and upgrade of various components, with the goal of exceeding a peak luminosity of 10 34 cm - 2 s - 1 (original design figure) around the year 2012; to eventually reach values close to 10 35 cm - 2 s - 1 . The increase in luminosity poses new challenges to the detector operation, both in terms of instantaneous and integrated particle rates. In CMS, the systems that have been identified as requiring substantial upgrades are the Tracker and the Level 1 trigger. The tracking system needs higher readout granularity and higher radiation tolerance, at the same time with reduced power dissipation and a smaller material budget, which are already limiting the performance of the present detector. The trigger system needs to include tracking information at Level 1, to maintain an acceptable rate without losing efficiency for physics channels. These requirements further complicate the design of a new Tracker detector and its readout architecture. This report describes the current status of our CMS Tracker upgrade activities.