The Limit To the Uhe Extraterrestrial Neutrino Flux From the Observations of Horizontal Air Showers At Eas-top

Extensive Air Showers at large zenith angles theta > 70-degrees (Horizontal Air Showers, HAS) are observed at the EAS-TOP array at Campo Imperatore (Gran Sasso Laboratories). The rate of these events exceeds the one due to primary cosmic rays (at this angles) and therefore these showers have to be generated by penetrating particles. Assuming that they are produced by atmospheric muons we derived the muon flux as F(mu)(> 30 TeV) = 1.1 x 10(-11) cm-2 s-1 sr-1, in good agreement with the underground measurements. The upper limits for diffuse neutrino radiation from these measurements is I(nu)(> 10(5) GeV) < 1.5 x 10(-8) CM-2 S-1 sr-1 for ''all-flavour'' neutrinos and dI(nueBAR)(E0)/dE(nueBAR) < 7.6 x 10(-18) CM-2 s-1 sr-1 GeV-1, for the resonant (E0 = m(W)2/2m(e) = 6.4 x 10(6) GeV) neutrinos.