  The ALEPH detector at LEP has been used to measure the momentum spectrum and
charge ratio of vertical cosmic ray muons underground. The sea-level cosmic ray
muon spectrum for momenta up to 2.5 TeV/c has been obtained by correcting for
the overburden of 320 meter water equivalent (mwe). The results are compared
with Monte Carlo models for air shower development in the atmosphere. From the
analysis of the spectrum the total flux and the spectral index of the cosmic
ray primaries is inferred. The charge ratio suggests a dominantly light
composition of cosmic ray primaries with energies up to 10^15 eV.
