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

Antiproton ($\bar{p}$) 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 $\nu$, as derived from the number of ``grey’’ tracks (slow protons and deuterons), is used to disentangle the $\bar{p}$ reabsorption from the production. By quantifying the amount of reabsorption of the $\bar{p}$ within the nucleus as a function of $\nu$, the annihilation within the nucleus is estimated and compared to the free annihilation cross section. Preliminary results on antilambda ($\bar{\mathrm{\Lambda }}$) production as a function of $\nu$ are also presented for comparison.