Preliminary results of an aging test of RPC chambers for the LHCb Muon System

The preliminary results of an aging test performed at the CERN Gamma Irradiation Facility on a single-gap RPC prototype developed for the LHCb Muon System are presented. The results are based on an accumulated charge density of 0:42 C=cm; corresponding to about 4 years of LHCb running at the highest background rate. We observe a rise in the dark current and noise measured with source off. The current drawn with source on steadily decreased, possibly indicating an increase of resistivity of the chamber plates. The performance of the chamber, studied with a muon beam under several photon flux values, is found to still fulfill the LHCb operation requirements. r 2003 Elsevier Science B.V. All rights reserved.