Anti-matter production in shocked ism clouds

The efficiency of the anti-proton (pBAR) production in interstellar clouds is increased by a factor 50 when the engendering cosmic-ray protons (CRs) experience diffusive acceleration by shocks. One can represent the pBAR/p observations by a conventional multi-phase model of the interstellar medium in which the volume-filling factor for shocked clouds is 1 % of that for all clouds. The pBAR/p ratio will reach a maximum value at an energy which depends upon a typical cloud size; the present observations give this size to be 1 pc. if individual cloud sizes do not get very much larger then thepBAR/p value may peak at a low energy, slightly above 10 GeV. The porosity factor of Cox and Smith (1974) is limited (Q0.2). Standard CR confinement models are examined using a diffusion equation approach. Most of the production ofpBAR's by any old CR population will occur in shocked clouds near the galactic plane. One does not need to assume an old CR population exists in order to explain thepBAR observations.