Astroparticle Physics

146 7 Secondary Cosmic RaysFig. 7.10Intensities of cosmic-ray particleswith energies > 1 GeV in theatmosphereTheir flux increases monotonically because additional neutrinosare permanently produced by particle decays.Since the energy spectrum of primary particles is relativelysteep, the energy distribution of secondaries also hasto reflect this property.Figure 7.11 shows the proton and muon spectra for var-ious depths in the atmosphere. Clearly visible is the trendthat with increasing depth in the atmosphere muons start todominate over protons especially at high energies.proton and muon spectraFig. 7.11Momentum spectra of protons andmuons at various altitudes in theatmosphere