Fluoride production in CMS Resistive Plate Chambers and aging study

The CMS resistive plate chambers (RPC) detectors operate with a gas mixture based on HydroFluoroCarbon components. The pollutants produced in the gas under high electrical discharge and radiation may accelerate the detectors aging, in particular the fluorine ions (F − ) produced as part of the compound hydrogen fluoride (HF) may damage the inner detector surface due to its high chemical reactivity. The HF production rate has been studied at CERN Gamma Irradiation Facility (GIF++) as a function of the background rate and the gas flow. Finally, the possible aging effects induced by the radiation in the CMS RPC system, including the HF effects, have been studied after almost seven years of operation.