Cosmic ray antiprotons and modified closed galaxy model

Abstract

Observations suggest that a small flux of secondary antiprotons (p), created in the interaction of cosmic ray nuclei with interstellar gas, should also be present in the primary cosmic radiation. Calculations based on accelerator data for the production of p and existing models for the propagation of cosmic rays, predict too small a flux of p compared with the finite flux observed recently1. Although the observed excess could be attributed to the existence of primary cosmic ray antimatter, the experimental upper limits2,3 of the ratio of antinuclei to nuclei of charge |Z| ≥ 2 seem to contradict this. Here we use a ‘modified closed galaxy’ model to attribute this excess to secondary antiprotons. In this model, ∼50% of the observed cosmic ray nucleons are of recent origin and they propagate according to the ‘nested leaky box’ model, while the rest propagate according to ‘closed galaxy’ model. This model explains the observations on p and e+, and predicts more D and 3He than do the existing models.