Development and testing of an upgrade to the CMS level-1 calorimeter trigger

When the LHC resumes operation in 2015, the higher centre-of-mass energy and high-luminosity conditions will require significantly more sophisticated algorithms to select interesting physics events within the readout bandwidth limitations. The planned upgrade to the CMS calorimeter trigger will achieve this goal by implementing a flexible system based on the μTCA standard, with modules based on Xilinx Virtex-7 FPGAs and up to 144 optical links running at speeds of 10 Gbps. The upgrade will improve the energy and position resolution of physics objects, enable much improved isolation criteria to be applied to electron and tau objects and facilitate pile-up subtraction to mitigate the effect of the increased number of interactions occurring in each bunch crossing. The design of the upgraded system is summarised with particular emphasis placed on the results of prototype testing and the experience gained which is of general application to the design of such systems.