Construction and test of the precision drift chambers for the ATLAS muon spectrometer

The Monitored drift tube (MDT) chambers for the union spectrometer of the A TLAS detector at the large hadron collider (LHC) consist of three or four l ayers of pressurised drift tub es on either side of a space frame carrying an optical deformation monitoring system. The chambers have to provide a tr ack position resolution of 40 mum with a single-tube resolution of at least 80 mum and a sense wire positioning accuracy of 20 mum (rms). The feasibil ity was demonstrated with the full-scale prototype of one of the largest MD T chambers with 432 drift tubes of 3.8 in length. For the ATLAS union spect rometer, 88 chambers of this type have to be built. The first chamber has b een completed with a mire positioning accuracy of 14 mum (rms).