We report new measurements of the muon spectra and the muon charge ratio at ground level in the momentum range from $200\mathrm{MeV}/c$ to $120\mathrm{GeV}/c$ for two different geomagnetic locations. Above $0.9\mathrm{GeV}/c$ the absolute spectra measured in the two locations are in good agreement and are about $10\%$ to $15\%$ lower than previous experimental results. At lower momenta the data show latitude dependent geomagnetic effects. These observations are important for the understanding of the observed neutrino anomaly.

• Received 23 July 1999

DOI:https://doi.org/10.1103/PhysRevLett.83.4241