Estimation of the Sea Level Muon Spectra at Different Zenith Angles below 10 TeV Energy

Abstract

The moderate energy primary cosmic ray nucleon spectrum has been calculated from the direct measurements of Webber et al., Seo et al., and Menn et al. along with the other results surveyed by Swordy. Using these directly measured primary mass composition results all particle primary nucleon energy spectrum has been constructed using superposition model to estimate the energy spectra of muons from the decay of the cosmic ray non-prompt and prompt mesons in the atmosphere. The Z-factors have been estimated from the CERN LEBC-EHS 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, and duly corrected for A--A collisions. Using these Z-factors the meson energy spectra in the atmosphere have been calculated. The sea level muon energy spectra at zenith angles 0°, 45°, 72°, and 75° have been derived from the decay of non-prompt mesons by adopting standard diffusion equation of hadronic cascades. The contribution of charmed mesons to muon spectrum has also been accounted by adapting the conventional procedure. The derived differential sea level muon energy spectra for energies ≤10 TeV have been found to follow the power law fits of the form N μ(E)≈ const. E -γ. Our estimated muon energy spectra at zenith angles ≤75° have been found comparable with the global spectrograph muon flux results of MARS, DEIS, and MSU groups.