Studies on the upgrade of the muon system in the forward region of the CMS experiment at LHC with GEMs

The LHC data-taking will resume in 2015 with energy of 13–14 TeV and luminosity
\nof 2 ÷ 5 × 1034 cm−2
\ns
\n−1
\n. At those energies, a considerable fraction of the particles produced
\npropagate in the high pseudo-rapidity regions. The proposal for the upgrade of the CMS muon
\nforward system involves Gas Electron Multiplier (GEM) chambers to be installed during the second
\nLHC Long Shutdown (LS2) covering the pseudorapidity range 1.5 < |η| < 2.2. This detector is
\nable to handle the extreme particle rates expected in this region when the LHC will be running at
\nhigher luminosity. The GEM is an excellent choice, as its high spatial resolution (order of 100 μm)
\nallows to combine tracking and triggering capabilities, which will improve the CMS muon High
\nLevel Trigger, the muon identification and the track reconstruction. Intense R&D has been going
\non since 2009 and it has lead to the development of several GEM prototypes and associated detector
\nelectronics. These GEM prototypes have been subjected to extensive tests in the laboratory and in
\ntest beams at the CERN Super Proton Synchrotron (SPS). This contribution will review the status
\nof the CMS upgrade project with GEMs, discussing also the trigger performance.