Characterization of triple-GEM detectors for the phase i muon system upgrade of the CMS experiment at LHC

Nowadays detectors based on Gas Electron Multipliers (GEM) technology are widely used in High Energy Physics. Thanks to their excellent spatial and time resolution, high particle rate capability and a close to 100% detection efficiency, GEM detectors meet all requirements for the upgrade of the CMS end cap. 144 large area trapezoidal triple-GEM detectors will be installed in 2019 in the first station of the end cap of CMS (Compact Muon Solenoid) experiment at the LHC. The features of the new GEM detectors will bring higher resolution of the muon transverse momentum to the first trigger level, lowering the rates in end cap region. This will allow to keep the same performance, both at trigger level and offline, as in the previous LHC runs despite the increased instantaneous luminosity of the colliding beams. In this contribution, after a general introduction and overview of the project, the design of full-size trapezoidal triple-GEM detectors wiU be described, followed by a detailed description of the quality control procedure. Six sites spread all over the world will participate to the assembly and quality control process. The INFN Bari section is one of those site since it successfully completed the commissioning of the labs and the validation of the test procedure.