The muon system of the Run II DO detector

We describe the design, construction, and performance of the upgraded D phi muon system for Run II of the Fermilab Tevatron collider. Significant improvements have been made to the major subsystems of the D phi muon detector: trigger scintillation counters, tracking detectors, and electronics. The Run II central muon detector has a new scintillation counter system inside the iron toroid and an improved scintillation counter system outside the iron toroid. In the forward region, new scintillation counter and tracking systems have been installed. Extensive shielding has been added in the forward region. A large fraction of the muon system electronics is also new. (c) 2005 Elsevier B.V. All rights reserved.