Test, integration, commissioning and installation of large drift tube chambers of the ATLAS barrel muon spectrometer

The ATLAS experiment at the Large Hadron CoIlider (LHC) at CERN is currently being assembled and to be ready to take data in 2007. In the barrel part of the muon spectrometer a toroidal air-core magnet is instrumented with three layers of monitored drift tube (MDT) chambers as precision tracking detectors. The installation of the muon detectors has started in January 2005. At the Max-Planck-Institut fur Physik and the Ludwig-Maximilians-University in Munich, 88 MDT chambers, each covering an area of 8 m², are being built for the outermost barrel region. The MDT chambers have to pass a series of stringent tests before installation to ensure their proper operation in the experiment. At the production site in Munich, these tests include gas tightness, high voltage stability and measurements of the noise rate, and the response to cosmic muons. In addition, the individual wire positions and electronic time offsets of the drift tubes are determined from the cosmic ray data. At CERN, a subset of the tests is repeated and the MDT chambers are integrated on a common support frame with resistive plate chambers (RPCs) of the trigger system. The results of the tests are stored in the ATLAS commissioning database and form an important basis for LHC data taking. We present the test methods and results, an overview on the integration work of the muon detectors and report on the experience with their installation in the ATLAS experiment.