  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.
