Calculation of the atmospheric muon flux motivated by the ATIC-2 experiment

Abstract

We calculate the cosmic ray muon flux at ground level using directly the primary cosmic ray spectrum and composition measured in the ATIC-2 balloon experiment. In order to extend the calculations to high energies, up to 100 TeV, we use the data of the GAMMA experiment as well as Zatsepin and Sokolskaya model. This model, supported by the ATIC-2 data, comprises contributions to the cosmic ray flux of three classes of astrophysical sources - the shocks from exploding stars, nova and supernova of different types. The muon flux computation is based on the method for solution of atmospheric hadron cascade equations in which rising total inelastic cross-sections of hadron-nuclear interactions as well as non-power-law character of the primary cosmic ray spectrum are taken into account. The calculated muon spectrum agrees well with measurements of L3+Cosmic and BESS-TeV, CAPRICE, Frejus, MACRO, LVD as well as other experiments.