Sea level muon spectrum below 1 TeV range derived from the latest primary spectrum

Muon energy spectrum in the vertical direction has been estimated from the recent primary cosmic ray nucleon spectrum expected from the direct measurements. We have found that the fit to the data of different primary elemental groups viz., p, He, CNO, Ne-S and Fe favoured different spectral indices. These directly measured primary mass composition results are precise and all particle primary nucleon spectrum has been constructed using superposition model for the calculation of the energy spectra of the cosmic ray secondaries in the atmosphere with the adoption of Feynman scaling hypothesis. Using such primary nucleon spectrum and the Z-factors from the CERN LEBC-EHS data on the Lorentz invariant cross section results on pp → π±X and pp → K±X inclusive reactions and FNAL data on π±p → π±X reactions for the estimation of hadronic energy moments duly corrected for A-A collisions the meson energy spectrum in the atmosphere have been calculated. The conventional meson atmospheric diffusion equation is employed here for the estimation of vertical muon energy spectrum from the conventional non-prompt meson decays. The derived differential sea level muon energy spectrum for energies ≤ 1 TeV has been found to follow the power law fit of the form Nμ (E) ∼ 0.55E-3.16. Our estimated vertical muon energy spectrum has been compared with the global muon flux data. We have also estimated the contribution of pions and kaons separately to the total muon flux and have found that ratio of the muon spectrum estimated from kaon decay to the muon spectrum from the pion decay increases with energy. (author)