Atmospheric muon-neutrino / electron-neutrino ratio in the multiGeV energy range

Abstract Data from the Kamiokande detector were used to study the atmospheric (v μ + v μ ) (v e + v e ) ratio in the multi-GeV energy range. The observed ratio of μ-like to e-like events relative to the calculated ratio, ( μ /e) data /( μ /e) MC = 0.57 -0.07 +0.08 ± 0.07, suggests that the atmospheric (v μ + v μ ) (v e + v e ) ratio is smaller than expected for these neutrino energies. Also studied was the zenith-angle dependence of the above ratio. Results of an analysis of neutrino oscillations are presented.