Latest results of longevity studies on the present CMS Resistive Plate Chamber (RPC) system for the HL-LHC phase

The HL-LHC phase will be a challenge for the existing CMS RPC system, as the expected operating conditions are much higher with respect to those for which the detectors have been designed. In addition, this could introduce non-recoverable aging effects, which can alter the detector properties. A longevity test is therefore needed to estimate the impact of HL-LHC conditions on the RPC detector performance. This will allow the validation of the RPC system for the expected harsher background conditions. A dedicated long-term irradiation program, designed to emulate the HL-LHC operational conditions, started in 2016 at the CERN Gamma Irradiation Facility (GIF++). A few RPC detectors are exposed to intense gamma radiation and their main detector parameters (currents, rate, resistivity) are continuously monitored as a function of the collected integrated charge. The detector performance has also been studied with muon beams. The latest results of the irradiation tests are presented