Certification of the ATLAS Muon Barrel stations

The muon spectrometer of the ATLAS experiment, which is scheduled to start data taking at the Large Hadron Collider at CERN in autumn 2007, comprises more than a thousand muon stations. These detectors have the double purpose of triggering on muon tracks as well as providing precise trajectory reconstruction. Monitored drift tube chambers are used for track reconstruction in all of the muon spectrometer except for a region close to the beam pipe in forward direction. Resistive plate chambers are used for triggering in the barrel region, while thin gap chambers are used in the end-caps. Since the ATLAS geometry allows only limited accessibility after stations are installed in the detector, a thorough testing and certification prior to installation is therefore crucial. This paper reviews the test procedure and the results at CERN for barrel chambers of type BO and BM, i.e. of stations for which a drift chamber is coupled with one or two resistive plate chambers. The final certification criteria is the passing of a cosmic ray test, for which a special setup has been built at CERN.