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

The LHC will restart in 2015 with a higher centre-of-mass energy and luminosity. To allow the CMS physics programme to fully exploit these increases the CMS Level-1 trigger must maintain similar efficiencies for searches and precision measurements to those achieved in 2012. With an average of 50 interactions occurring in each bunch-crossing, it will be challenging to select interesting physics events within the readout bandwidth limitations. The CMS calorimeter trigger is being upgraded to enable the more sophisticated algorithms needed to handle the high-luminosity conditions and to add the flexibility to adapt to changing LHC performance and physics priorities.The design of the upgraded system is summarised, performance of the prototype hardware presented, and the results of integration tests between subcomponents shown.