D0 forward-angle muon tracking detector and its gas system

The design of the new D0 forward angle muon tracking detector and its gas system are described in this paper. The new D0 forward muon tracking detector is based on a minidrift tube technology. The minidrift tubes are operated in proportional mode using a fast nonflammable gas mixture. The basic operational characteristics of this gas mixture and the effects of impurities are presented. Special requirements of the gas system that lead to our design choices are discussed. The gas distribution, recirculation, control, and monitoring system are described.