New measurement of the flux of atmospheric muons

We report a new measurement of the momentum spectra of both positive and ne gative muons as a function of atmospheric depth in the momentum range 0.3-2 and 0.3-40 GeV/c, respectively. The measured flux values have been compare d with the spectra obtained from simulations, which were carried out to int erpret the atmospheric neutrino data. We find that our data disagree with t he results from the simulations. The ratio of the flux of muons derived fro m simulations to that measured is at largest 1.8 and varies with atmospheri c depth and muon momentum.