[en] A total of 110 drift chambers, each containing two 60 cm wide drift cells with anode wires up to 10.4 m long, have been installed on the OPAL detector at the LEP electron-positron collider in CERN, Geneva. The chambers allow measurement of space points on the trajectory of a charged particle: Coordinates transverse to the wire direction are reconstructed to an accuracy of 2 mm using conventional drift-time measurements, while a novel arrangement of diamond shaped cathode pads allows location of the track along the wire to an accuracy of 1.5 mm. This is achieved by three measurements of increasing ambiguity but also increasing accuracy. The techniques developed to analyse the signals from the cathode pads are described in some detail. (orig.)

[en] The barrel part of the OPAL muon detector consists of 110 drift chambers forming four layers outside the hadron absorber. Each chamber covers an area of 1.2 m by up to 10.4 m and has two cells with wires parallel to the beam and a drift distance of 297 mm. A detailed description of the design, construction, operation and performance of the sub-detector is given. The system has been operating successfully since the start of LEP in 1989. ((orig.))