The gas monitoring system for the Resistive Plate Chamber detector of the CMS experiment at LHC

Due to its large volume (18 m 3 )the Resistive Plate Chamber (RPC) detector of the Compact Muon Solenoid (CMS) experiment at the LHC proton collider (CERN, Switzerland) will employ a gas re-circulation system. Since the mixture composition and quality are crucial issues for the detector operation, CMS-RPC will use an online gas analysis and monitoring system. An overview of both the CMS-RPC gas system and gas monitoring system is given and the project parameters are described.