Cosmic ray physics with the ARGO-YBJ experiment

Cosmic ray physics in the 1012–1015 eV primary energy range is among the main scientific goals of the ARGO-YBJ experiment. The detector, located at the Cosmic Ray Observatory of Yangbajing (Tibet, P.R. China) at 4300 m a.s.l., is a full coverage Extensive Air Shower array consisting of a carpet of Resistive Plate Chambers of about 6000 m2. The apparatus layout, performance and location offer a unique possibility to make a deep study of several characteristics of the hadronic component of the cosmic ray flux in an energy window marked by the transition from direct to indirect measurements. In this work we will focus on the experimental results concerning the measurements of the primary cosmic ray energy spectrum and of the proton-air cross-section. The all-particle spectrum has been measured, by using a bayesian unfolding technique, in the 1–100 TeV energy region. The proton-air cross-section has been measured at the same energies, by exploiting the cosmic ray flux attenuation for different atmospheric depths (i.e. zenith angles). The total proton–proton cross-section has then been estimated at center of mass energies between 70 and 500 GeV, where no accelerator data are currently available.