Cosmic-ray muon spectrum up to 1 TeV at 75° zenith angle

The spectrum of about 6 ×{} 10⁵ muons in the zenith angle range θ=68^∘-82^∘ and the energy range E=1-1000 GeV has been measured by a Kiel-Desy collaboration at Hamburg. The data are represented by a simple form fit which goes as E^-2.57sec θ for the integral spectrum at very high energies. indicating that the galactic cosmic-ray nucleon spectrum is flatter than E^-2.75 beyond 1000 GeV.