Upgrade of the CMS Muon system with Triple-GEM detectors

During Run-2 the Large Hadron Collider (LHC) has delivered instantaneous luminosities up to 2×l034cm2s−1, being twice the design Luminosity. During the second Long Shutdown (LS2) the accelerator complex will be upgraded for the next Run-3 and anticipating the future High Luminosity LHC (HL- LHC) which will start taking data in 2025 with an instantaneous luminosity of 5 × 1034cm_2s_1 or even 7.5 × 1034cm_2s_1 in the ultimate performance scenario. To cope with the corresponding increase in background rates in the forward muon system of CMS and to improve the trigger capabilities to keep the trigger rate at an acceptable level while not compromising the physics potential, the forward muon system of the CMS experiment will be upgraded with Gas Electron Multiplier (GEM) and Resistive Plate Chamber (RPC) detectors. In 2019 triple-GEM detectors will be installed in the first station of the muon detector, while a second station will be installed in 2022. Furthermore to enlarge the acceptance of the muon spectrometer a new station is considered to be installed directly behind the new High-Granularity Calorimeter during LS3 (2023–2024). We will present an overview of the CMS muon detector upgrade with Triple-GEM detectors: operational experience obtained from a test-slice installation in 2017, the production and quality control of the 144 Triple-GEM chambers for the first station, together with the design and prototyping of the Triple-GEM upgrades envisioned until 2024 along with the schedule for their production and quality control.