Measurement of the proton-air inelastic cross section at root s approximate to 2 Tev from the EAS-TOP experiment

The proton-air inelastic cross section (sigma(inel)(p-air)) is measured at root s approximate to 2 TeV at the EAS-TOP extensive air shower experiment by studying the absorption length of cosmic ray proton primaries cascades reaching the maximum development at the observation level. Primary energies, in the region E-0 = (1.5 divided by 2.5) 10(15) eV, are selected through the EAS muon number (N-mu), and proton originated cascades at maximum development are selected by means of the shower size (N-e). The observed absorption length (lambda(obs)) is a convolution of the proton-air interaction length (lambda(p-air)) and of the shower and detector fluctuations. The conversion factor k = lambda(obs)/lambda(int) is obtained by means of simulations performed with the CORSIKA code and the QGSJET II and SIBYLL interaction models. The obtained value of the p-air inelastic cross section at root s approximate to 2 TeV is sigma(inel)(p-air) = 338 +/- 21(stat) +/- 19(syst) - 28(syst) mb. The statistical and systematic uncertainties, as well as the relationships with the pp ((p) over barp) total cross section measurements are discussed.