CMS Outer Tracker Upgrade Plans

With the upgrade of the LHC to the hi gh - luminosity LHC (HL - LHC), the tracker syst em of the CMS experiment will have to be upgraded. It is planned to use information from the tracker in the first level trigger of CMS. For this purpose CMS plans to introduce p T modules which will provide trigger capability. The luminosity increase by a f actor of five in th e HL - LHC compared to the design luminosity will lead to higher occupancy and radiation levels in the sensors. In order to cope with these, the strip granularity will be significantly increased and the sensors of the upgraded tracke r will have to be cooled to a temperature of - 20°C. Moreover, the sensor material and design have to be chosen carefully in order to withstand the anticipated radiation. This paper introduces the concept of the p T module and give s an overview of the ongoing R&D activities concerning the silicon sensor material