Time resolution and aging properties of the MWPCs for the LHCb Muon System

We present results on time resolution, efficiency in a 20 ns time window and response uniformity obtained in the last three years at the PS-T11 beam test facility at CERN on several MWPC prototypes for the LHCb Muon System. In addition we discuss results from an extensive aging test that has been performed irradiating several prototypes with 1.25 MeV γ from a high intensity 60 Co source at the ENEA Casaccia Calliope Facility. A brief summary of the main results on aging properties of bakelite RPCs initially foreseen for the LHCb Muon System is also given.