A muon identification and combined reconstruction procedure for the ATLAS detector at the LHC at CERN

Muon identification and high momentum measurement accuracy is crucial to fully exploit the physics potential that will be accessible with ATLAS experiment at the LHC. The muon energy of physics interest ranges in a large interval from few GeV, where the b-physics studies dominate the physics program, up to the highest values that could indicate the presence of new physics. The muon detection system of the ATLAS detector is characterized by two high precision tracking systems, namely the Inner Detector and the Muon Spectrometer plus a thick calorimeter that ensures a safe hadron absorption filtering with high purity muons with energy above 3 GeV. In order to combine the muon tracks reconstructed in the Inner Detector and the Muon Spectrometer the Muon Identification (MUID) Object-Oriented software package has been developed. The purpose of the MUID procedure is to associate tracks found in the Muon Spectrometer with the corresponding Inner Detector track and calorimeter information in order to identify muons at their production vertex with optimum parameter resolution. The performance of these two combined systems has been evaluated with single muons of fixed transverse momentum and with full physics events.