High-precision, large-volume, particle tracking

Muon measurement in the ATLAS detector at the Large Hadron Collider (LHC) to be built at the European Center for Particle Physics, CERN, requires a tracking precision of 50 mu m along particle trajectories of typical path lengths of $9 5-20 m. The overall active area to be covered by the tracking devices, so-called Monitored Drift Tube Chambers, is 5,500 m/sup 2/. Requirements on fabrication, chamber alignment and operation are, in many respects, unprecedented and $9 can only be met by a combination of novel optical monitoring devices and a high-precision chamber construction technique. (1 refs).