Cosmic Ray Antiprotons

Interstellar (IS) cosmic rays consist mainly of protons with a smaller admixture of heavier nuclei. Antiprotons (p’s) occur at an abundance of 10 of p’s. These energetic particles, kinetic energy K > 10 MeV, are Galactic in origin, not to be confused with the much denser solar wind plasma, with much lower K. The relative element abundances in cosmic rays (CRs) indicate that CR primaries are ionized and accelerated in the IS medium, probably by supernova shocks. 1,2 Once accelerated to high energies, the primaries induce the production of further CRs, the secondaries (e’s, p’s, certain isotopes), in the IS medium and at local sites in the Galaxy.