Cosmic ray light component (p+He) energy spectrum measured by the ARGO–YBJ experiment in the 3–3000 TeV energy range

The energy spectrum and composition of Cosmic Rays (CR) play an important role in the understanding of the acceleration and propagation mechanisms of high-energy particles. The ARGO–YBJ experiment (Yanbajing, Tibet, P. R. China, 4300 m a.s.l.) is a ground-based air shower detector designed in order to detect showers produced by primaries in the 1–104 TeV energy range. The high spacetime resolution of the detector allows a precise measurement of the lateral particle distribution. This information can be exploited in order to discriminate showers produced by primaries of different mass. In this work the measurement of the Proton plus Helium energy spectrum is presented in the 1–3000TeV energy range. A deviation from a single power law is clearly evident at energies less than 1PeV