Low-Energy Antinucleon-Nucleus Interaction Revisited

TL;DR

This paper revisits antinucleon-nucleus interactions, analyzing annihilation cross sections of antiprotons and antineutrons, revealing Coulomb effects and proposing future experimental measurements for better understanding.

Contribution

It provides new insights into Coulomb interactions in antinucleon annihilations and suggests experimental approaches to compare proton and neutron interactions on the same targets.

Findings

Coulomb focusing observed below 200 MeV/c for antiprotons

Almost no charge dependence above 200 MeV/c

Optical potential helps interpolate and compare antiproton and antineutron interactions

Abstract

Annihilation cross sections of antiprotons and antineutrons on the proton between 50 and 400 MeV/c show Coulomb focusing below 200 MeV/c and almost no charge-dependence above 200 MeV/c. Similar comparisons for heavier targets are not possible for lack of overlap between nuclear targets studied with $\bar p$ and $\bar n$ beams. Interpolating between $\bar p$-nucleus annihilation cross sections with the help of an optical potential to compare with $\bar n$-nucleus annihilation cross sections reveal unexpected features of Coulomb interactions in the latter. Direct comparisons between $\bar n$-nucleus and $\bar p$-nucleus annihilations at very low energies could be possible if $\bar p$ cross sections are measured on the same targets and at the same energies as the available cross sections for $\bar n$. Such measurements may be feasible in the foreseeable future.