Design of a trigger module for the CMS Tracker at SLHC

The CMS experiment is planning a major upgrade of its tracking system to adapt to an expected increase in luminosity of the LHC accelerator to 1035 cm-2.s-1. It will then have to cope with several hundred interactions per bunch crossing and fluxes of thousands of charged particles emerging from collisions. CMS requires tracker data to contribute to the first level trigger, to maintain the present 100kHz rate while increasing the trigger decision latency by only a few μs. A key part of a system to achieve this will be the design of a suitable module to generate trigger primitives. One possible solution is based on so-called “stacked tracker modules” using closely spaced, coarsely pixellated sensor layers situated at intermediate radius within the tracker volume. A basic readout architecture is proposed and some of the electronic implications are described. Estimates of likely power consumption are given, and data rates and link bandwidth requirements.