Development and performance of Micropattern Gaseous Detectors for the CMS muon system upgrade

This PhD work is involved in the framework of the upgrade of the muon system of the Compact Muon Solenoid (CMS) experiment. The CMS muon system during the first period of operation (Run 1) of the Large Hadron Collider (LHC)was instrumented with three different kinds of gaseous detectors: Drift Tubes(DT) in the barrel, Cathode Strip Chambers (CSC) in the endcaps and Resistive Plate Chambers (RPC) as complementary technology in both regions. This configuration obtained excellent results during Run 1, but it needs to be improved in order to keep them also in the next LHC phases, during which a huge increase of the LHC luminosity is foreseen. These conditions will deeply affect the performance of the detectors as they will induce a remarkable growth of the pileup and a huge worsening of the background conditions. In order to face these challenges, the CMS Collaboration is performing a general upgrade of all the subsystems, involving also the muon system which will undergo deep changes. Beyond a general improvement of the installed detectors, including interventions both on the chambers themselves and their electronics, the muon system upgrade foresees also the installation of new muon stations in the high η region of the muon system, region fundamental for many physics channels, like for example H → ZZ∗ → 4μ. This region was suffering from lack of redundancy, as the technologies available at that time were not considered able to cope with the high rates and high background characteristic of those regions. The proposed new stations are in total five: the first three, called GE1/1, GE2/1 and ME0, foresee the implementation of Micropattern Gaseous Detectors (MPGD), while for the last two, RE3/1 and RE4/1, improved versions of RPC are being considered. This work was involved in the activities for the implementation of the MPGD stations, in particular GE1/1 and ME0.