Latest results on cosmic ray physics from the ARGO-YBJ experiment

Cosmic ray physics in the 10^12–10^15 eV primary energy range is among the main scientific goals of the ARGO-YBJ experiment. The detector, located in the Cosmic Ray Observatory of Yangbajing (Tibet, China) at 4300 m a.s.l., is a full coverage extensive air shower array consisting of a carpet of Resistive Plate Chambers (RPCs) distributed over an area of more than 10 000 m2. The apparatus layout, performance and location offer a unique opportunity for a detailed 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. Moreover, the analog readout of the RPC signals indeed provides a powerful tool to study, with unprecedented resolution and without saturation, the extensive air shower space–time structure down to few meters from its axis. Latest results concerning the study of cosmic ray energy spectrum, mass composition and arrival directions will be given together with the search for an antiproton signal, the proton–air cross-section measurement, the study of the interplanetary magnetic field, and the effects of the geomagnetic field on secondary particles. Furthermore, particle distributions close to the shower axis are being extensively studied, also giving new inputs, in the very forward region, to the hadronic interaction models currently used for understanding particle physics and cosmic rays up to the highest energies