Antiproton-Nucleon Annihilation Process (Antiproton Collaboration Experiment)

Abstract

Thirty-five antiproton stars have been found in an emulsion stack exposed to a 700-Mev/c negative particle beam. Of these antiprotons, 21 annihilate in flight and three give large-angle scatters ($\theta >15\mathrm{}°$, $T_{\overline{p}}>50\mathrm{}$ Mev), while 14 annihilate at rest. From the interactions in flight we obtain the total cross section for antiproton interaction: $\frac{{\sigma }_{\overline{p}}}{{\sigma }_0}=2.9\mathrm{}\pm 0.7$, where ${\sigma }_0=\pi {R_0}^2$ and $R_0=1.2\mathrm{}\times {10}^{-13\mathrm{}}{A}^{\frac{1}{3}}$ cm. This cross section was measured at an average antiproton energy of ${\overline{T}}_{\overline{p}}=140\mathrm{}$ Mev.