Trigger detectors for the LHCb muon system VCI 2001

The muon detector of LHCb consists of five tracking stations which are placed along the beam axis and separated by iron filters. A muon trigger requires the coincidence of hits in all stations which demands a time resolution better than 3 ns and an efficiency of >99% for each station. Resistive plate chambers and multi wire proportional chambers with wire and cathode readout are used for this purpose. The general signal formation and timing characteristics of RPCs and MWPCs for this application are discussed and compared. Test results of chamber prototypes are presented.