The ATLAS RPC trigger chamber system

The ATLAS muon spectrometer has a dedicated detector to trigger on muons of transverse momentum larger than 6 GeV/c. The trigger detectors at pseudorapidity ∣η∣<1.0, consist of 1116 Resistive Plate Chambers (RPCs), for a total coverage of ∼3650 m2. They have been produced and tested with cosmic rays in Italy. The RPCs are currently being integrated at CERN with the precision chambers (Monitored Drift Tube (MDT)) to build the 380 muon stations required for the muon spectrometer. r issue regarding the RPCs is the understanding of the ageing process after 10 years of operation at the LHC Collider. Results of 2 years of ageing studies performed at CERNʹs Gamma Irradiation Facility on samples of production chambers will be presented.