Operations and performance of the CMS RPC muon system at LHC

The Compact Muon Solenoid (CMS) experiment is one of the two general-purpose detectors at the CERN Large Hadron Collider. CMS combines three different gaseous detector technologies to trigger and reconstruct muons: Drift Tubes in the barrel region ( | η | < 1.2 ), Cathode Strip Chambers in the endcaps ( 0.9 < | η | < 2.4 ) , and Resistive Plate Chambers (RPCs) in both regions, as a dedicated muon trigger. We report on the operations and performance of the RPC system after 2 years of LHC running with increasing instantaneous luminosity. Special attention is given to the stability of the system and to the working point calibration procedures.