Measurement of the antiproton/proton ratio at few-tev energies with the argo-ybj experiment

Cosmic rays are hampered by the Moon, therefore a deficit of cosmic rays in its direction is expected (the so-called Moon shadow). The Earth-Moon system acts as a magnetic spectrometer and the paths of primary protons and antiprotons are deflected in an opposite sense in their way to the Earth. This effect allows, in principle, the search of antiparticles in the opposite direction of the observed Moon shadow. Cosmic ray antiprotons provide an important probe for the study of cosmic-ray propagation in the interstellar space and to investigate the existence of Galactic dark matter. With the data of the ARGO-YBJ experiment, an upper limit of the p̄/p fluxes ratio in the few-TeV energy region is set to a few percent with a confidence level of 90%. Copyright © 2009 by INFN.