Lateral distribution of cosmic ray muons underground: results from the CosmoALEPH experiment

The CosmoALEPH experiment, located underground at the LEP e+e- storage ring at CERN at a depth of 320 m water equivalent, was used to study the chemical composition of primary cosmic rays up to 10 PeV energies from the measurement of high energy muons, created in extensive air showers by interactions of primary nuclei in the atmosphere. The Time Projection Chamber and the Hadron Calorimeter of the ALEPH detector and six scintillator stations located at distances up to 1 km from each other were used to analyse the decoherence curve, multiplicity and transverse momentum distributions of energetic cosmic muons. The experimental data were compared with predictions from different CORSIKA Monte Carlo models and mass composition approaches resulting in a dominant light composition in the energy range from about 100 GeV to 10 PeV. (orig.)