New Insight into Antiproton Production and Reabsorption Using Proton-Nucleus Collisions at the AGS

Antiproton (p̄) yields are presented for proton-nucleus collisions, with targets Be, Cu, and Au, at beam momenta of 12.3 and 17.5 GeV/c. In addition to target size and beam momentum, the number of projectile collisions ν, as derived from the number of “grey” tracks (slow protons and deuterons), is used to disentangle the p̄ reabsorption from the production. By quantifying the amount of reabsorption of the p̄ within the nucleus as a function of ν, the annihilation within the nucleus is estimated and compared to the free annihilation cross section. Preliminary results on antilambda (Λ̄) production as a function of ν are also presented for comparison.