Measurement of the Proton Maximum Acceleration Energy in Galactic Cosmic Rays

Cosmic rays represent one of the most important energy transformation processes of the universe. They bring information about the surrounding universe, our galaxy, and very probably also the extragalactic space, at least at the highest observed energies. More than one century after their discovery, we have no definitive models yet about the origin, acceleration and propagation processes of the radiation. The main reason is that there are still significant discrepancies among the results obtained by different experiments, probably due to some still unknown systematic uncertainties affecting the measurements. In this paper, we will focus on the detection of galactic cosmic rays in the 10${}^{15}$ eV energy range, where the so-called \emph{`knee’} in the all-particle energy spectrum is observed. The measurement of the (p+He) energy spectrum is presented and discussed.