Detection of atmospheric muons using ALICE detectors

A large number of atmospheric muon events were recorded during 2009 for the calibration, alignment and commissioning of most of the ALICE (A Large Ion Collider Experiment at the CERN LHC) detectors. Specific triggers, not used during the LHC collisions, were implemented to take these data. Some triggers select atmospheric muons, with zenith angle between 0° and 60°, crossing the central barrel of ALICE and reconstructed with the TPC (Time Projection Chamber). The muon multiplicity of the event, and for each muon the momentum, the sign, the direction and the spatial coordinates are measured. We present a first analysis of these events with correlations between some observables. Another trigger selects horizontal muons with zenith angle between 65° and 85°. These muons are detected and reconstructed with the Forward Muon Spectrometer. The angular distribution and some characteristics of these rare events are discussed.