Monte Carlo simulation of the cosmic muon charge ratio
The muonic component of air showers is sensitive to the mass and energy of the primary cosmic ray and is the most abundant component of charged particles arriving at the surface, and able to penetrate deeply underground. The muon charge ratio, defined as the number of positive over negative charged muons, is a very interesting quantity for the study of hadronic interactions at high energies and the nature of cosmic ray primaries. Furthermore, Earth's atmosphere is the development medium of cosmic air showers before they arrive at the ground. Therefore, variations in the density of the atmosphere between seasons must be studied. It is also very important to account for the zenith angular dependence of atmospheric muons, in particular for showers penetrating the atmosphere at high zenith angles.
We present a study of the muon charge ratio using Monte Carlo simulations of two cosmic primaries, proton and iron, of 100 TeV and 1 PeV energies, and with a zenith angle of 0o to 60o. The dependence on the direction of extensive air showers EAS and their radial distance appears to be very pronounced. In addition, the muon density is discussed assuming the Central European Atmosphere in June and December.