Performance study of a MWPC prototype for the LHCb muon system with the ASDQ chip

We report results from a beam test evaluating the front­end electronics for Multi­Wire­Proportional­Chambers (MWPCs) for the LHCb Muon System. The ASDQ chip with an adaption fulfils the requirements for the detectors in the entire Muon System. A time resolution of 3.2 ns at an operating voltage 3.15 kV was achieved with the gas mixture Ar(40%)CO 2 (50%)CF 4 (10%), translating into an efficiency of 99.5% for a 20 ns time window. An efficiency of more than 95% in a 20 ns time window is obtained for voltages above 2.95kV for all types of pads studied. Hence, the efficiency plateau is about 500 Volts.