CMS Muon System Phase 2 Upgrade with triple-GEM detectors

The Compact Muon Solenoid (CMS) detector installed at the CERN Large Hadron Collider (LHC) has an extensive muon system which provides information simultaneously for identification, track reconstruction and triggering of muons. As a consequence of the extreme particle rate and high integrated charge, the essentiality to upgrade the LHC has given rise to the High Luminosity phase of the LHC (HL-LHC) project so that the CMS muon system will be upgraded with superior technological challenges. The CMS GEM collaboration offers a solution to equip the high-eta region of the muon system for Phase 2 (after the year 2017) with large-area triple-layer Gas Electron Multiplier (GEM) detectors, since GEMs have the ability to provide robust and redundant tracking and triggering functions with an excellent spatial resolution of order 100 micron and a high particle rate capability, with a close to 100pct detection efficiency. In this contribution, the present status of the triple-GEM project will be reviewed, and the significant achievements from the start of the R and D in 2009 will be emphasized. Fundamental design of the triple-GEM detectors proposed for installation in different stations of the CMS muon system will be described along with the incorporated front-end electronics, data-acquisition system and the results from the detector tests.