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

The proton-air inelastic cross section measurement at s ≈ 2 TeV from the EAS-TOP Extensive Air Shower experiment is reported. The technique exploits cosmic ray proton primaries, in the energy region E 0 = ( 1.5 ÷ 2.5 ) ⋅ 10 15 eV , studying the absorption length of their cascades when detected at maximum development. Primary energies are selected through the EAS muon number ( N e ), and proton originated cascades at maximum development by means of the shower size ( N e ). 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 = λ o b s / λ i n t ), from the observed absorption length ( λ o b s e x p ) to the interaction length ( λ p − air ). The obtained value of the p-air inelastic cross section at s ≈ 2 TeV is σ p − air i n e l = 338 ± 21 ( s t a t ) ± 19 ( s y s t ) − 28 ( s y s t ) mb . The relevant issue of systematic uncertainties have been studied. The connections with the pp ( p ¯ p ) total cross section measurements are discussed.