Study of discharges observed in the CMS GE1/1 station during LHC Run-3

Since July 2022, GE1/1, the first station using Gas Electron Multiplier (GEM) technology in the Compact Muon Solenoid (CMS) experiment, has been participating in the data-taking in proton–proton (p–p) collisions. This station is the first of three (GE1/1, GE2/1 and ME0) planned to be installed in CMS, to cope with the challenging conditions given by the upgrade of luminosity of the Large Hadron Collider (High-Luminosity LHC program, or HL-LHC) (Colaleo et al., 2015) . This contribution illustrates in detail the analysis developed to monitor the discharge rate per each LHC fill and the strategies developed to operate the chambers safely. An important intervention was the modification of the High Voltage (HV) power system, to correctly power detectors affected by short circuits in the GEM foils. The contribution will also present the current status of operation for GE1/1 in Run-3 in 2023 and the next steps to be implemented to improve the behaviour of the detectors.