THE ANTI-NUCLEI PRODUCTION OF OUR GALAXY

The discovery of a single anti-helium nucleus in the cosmic ray flux w ould definitely point toward the existence of stars and even of entire galaxies made of anti-matter. The presence of anti-nuclei in cosmic r ays has actually profound implications on the fundamental question of the baryon asymmetry of the universe. It is therefore crucial to deter mine the amount of anti-matter which our own galaxy already produces t hrough the spallation of high-energy protons on the interstellar gas o f the galactic disk. We have used [1] here a coalescence model to asse ss the amount of anti-deuterium and anti-helium (3)(H) over bar e pres ent in cosmic rays together with anti-protons. The propagation of cosm ic rays in the galaxy is described through a two-zone diffusion model which correctly describes the observed abundances. We find that the (D ) over bar/p ratio exceeds 10(-9) above a momentum per anti-nucleon of similar to 4 GeV/c. Would the universe be purply made of matter, the AMS collaboration should be able to detect a few anti-deuterons during the space station stage of the experiment. However, the (3)(H) over b ar e/p abundance does not exceed similar to 4 x 10(-13). Heavier anti- nuclei are even further suppressed.