New Measurement of the Flux of Atmospheric Muons

We report a new measurement of the momentum spectra of both positive and negative muons as a function of atmospheric depth in the momentum range 0.3–2 and $0.3–40\mathrm{GeV}/c$, respectively. The measured flux values have been compared with the spectra obtained from simulations, which were carried out to interpret the atmospheric neutrino data. We find that our data disagree with the results from the simulations. The ratio of the flux of muons derived from simulations to that measured is at largest 1.8 and varies with atmospheric depth and muon momentum.