The forward muon detector of the CMS experiment

We describe the forward muon detector of the CMS experiment at the LHC accelerator. The CMS forward muon detector is composed of 4 independent stations, each station being made of a mosaic of six-layer cathode strip chambers. Cathode strip chambers are multiwire proportional chambers with a cathode segmented in strips to provide a precise measurement of the coordinate across the strip direction. The forward muon detector has to be able to measure hits along muon tracks with a precision of 75–150 μm per station as well as providing an accurate time tag to be used by the first level trigger. The forward muon detector will cover an area of more than 1000 m2 representing one of the largest system of proportional chambers ever built. We also present some results obtained using muon test beams with some cathode strip chamber prototypes.