EAS-TOP: The proton-air inelastic cross-section at

The proton-air inelastic cross section measurement at from the EAS-TOP Extensive Air Shower experiment is reported. The technique exploits cosmic ray proton primaries, in the energy region , studying the absorption length of their cascades when detected at maximum development. Primary energies are selected through the EAS muon number (Ne), and proton originated cascades at maximum development by means of the shower size (Ne). The shower and detector fluctuations are obtained with simulations performed using the CORSIKA code and the QGSJET II and SIBYLL interaction models. The simulations provide the conversion factor (k=λobs/λint), from the observed absorption length () to the interaction length (λp−air). The obtained value of the p-air inelastic cross section at is . The relevant issue of systematic uncertainties have been studied. The connections with the pp () total cross section measurements are discussed.