Interpretation of the Low-Energy Cosmic Ray Antiproton/Proton Ratio

Abstract

We examine the solar modulation of cosmic ray protons and antiprotons, and discuss the resulting effects on the low-energy antiproton/proton ratio at 1 AU. We find that the anitiproton/proton ratio at energies >3 GeV is a useful diagnostic of cosmic ray transport in the Galaxy. However, at energies <l GeV the expected ratio is much more uncertain because of variation in the relative modulation of protons and antiprotons and uncertainties in the interstellar spectra. As a result, it is recouunended that attention be given instead to interpretation of the cosmic ray antiproton energy spectrum measured rather than to the antiproton/proton ratio.