Atmospheric or Cosmic Ray Neutrinos

TABLE V Summary of Recent Measured and Calculated Solar Neutrino Fluxes 

TABLE VI Summary of the Ratio of Ratios = Measured Ratio (/x/e)/Expected Ratio [pJe) from atmospheric neutrinos 

FIGURE 8 Calculated atmospheric neutrino flux, + v ), as a function of . 

The three-body decay of muons includes a charged electron and a neutrino and antineutrino, each of the type or flavor to conserve a separate lepton number, i.e one muon type and one electron type, while the meson (pion or kaon) decay produces almost exclusively muon type neutrinos or antineutrinos (see Table I). As a consequence, atmospheric neutrinos interacting in a detector such as K-II or SuperK would be expected to produce, on average, twice as many muons as electrons. The double ratio / meas (no. of muons/no. of electrons) divided by / caic (no. of muons/ no. of electrons) was explored in K-II and subsequently in Super K, and the results are shown in Table VI, where it is seen that apart from one experiment (Frejus less than three standard deviations from the average of the other experiments), the double ratio / meas// caic is significantly different from the expected value of unity. 

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