Extensive aging test of two prototypes of four-gap MWPC for the LHCb Muon System

We present the results of an aging test on two prototypes of four-gap MWPC designed for the LHCb Muon System. The test was carried out with a Co source, the Calliope gamma facility at ENEA-Casaccia Research Center, near Rome. We monitored the currents in the two chambers under test and in a similar chamber used as a reference. Over a period of thirty days, we integrated a charge up to 440 mC/cm of wire in the chamber in gas open mode, equivalent to 4.6 LHC years (in region M1R2), without any appreciable deterioration of the detector gas gain.