High-rate performance of the MWPCs for the LHCb muon system

The high-rate performance of a multiwire proportional chamber of the LHCb muon detector was tested. The chamber, equipped with the final front-end electronics, was tested using a ∼100GeV muon beam superimposed on a 662 keV γ flux of variable intensity produced by the 137Cs radioactive source of the CERN Gamma Irradiation Facility (GIF). No significant variation in the muon detection efficiency or in the time response of the chamber was observed at the highest gamma rate.