Upgrade of the CMS muon trigger system in the barrel region

To maintain the excellent performance shown during the LHC's Run-1 the Level-1 Trigger of the Compact Muon Solenoid experiment underwent a significant upgrade. One part of this upgrade is the re-organization of the muon trigger path from a subsystem-centric view in which hits in the drift tubes (DT), the cathode strip chambers (CSC), and the resistive plate chambers (RPC) were treated separately in dedicated track-finding systems to one in which complementary detector systems for a given region (barrel, overlap, and endcap) are merged at the track-finding level. This fundamental restructuring of the muon trigger system required the development of a system to receive track candidates from the track-finding layer, remove potential duplicate tracks, and forward the best candidates to the global decision layer. An overview will be given of the new track-finder system for the barrel region, the Barrel Muon Track Finder (BMTF), as well as the cancel-out and sorting layer: the upgraded Global Muon Trigger (mu GMT). Both the BMTF and mu GMT have been implemented in a Xilinx Virtex-7 card utilizing the microTCA architecture. While the BMTF improves on the proven and well-tested algorithms used in the Drift Tube Track Finder during Run-1, the mu GMT is an almost complete re-development due to the re-organization of the underlying systems from track-finders for a specific detector to regional track finders covering a given area of the whole detector. Additionally the mu GMT calculates a muon's isolation using energy information received from the calorimeter trigger. This information is added to the muon objects forwarded to the global decision layer, the so-called Global Trigger. (C) 2016 The Authors. Published by Elsevier B.V.