Unified optical-model approach to low-energy antiproton annihilation on nuclei and to antiprotonic atoms Original Research Article

A successful unified description of View the MathML source nuclear interactions near E=0 is achieved using a View the MathML source optical potential within a folding model, View the MathML source, where a View the MathML source potential View the MathML source is folded with the nuclear density ρ. The potential View the MathML source fits very well the measured View the MathML source-annihilation cross sections at low energies (View the MathML source MeV/c) and the 1s and 2p spin-averaged level shifts and widths for the View the MathML sourceH atom. The density-folded optical potential View the MathML source reproduces satisfactorily the strong-interaction level shifts and widths over the entire periodic table, for A>10, as well as the few low-energy View the MathML source-annihilation cross sections measured on Ne. Both View the MathML source and View the MathML source are found to be highly absorptive, which leads to a saturation of reaction cross sections in hydrogen and on nuclei. Predictions are made for View the MathML source-annihilation cross sections over the entire periodic table at these very low energies and the systematics of the calculated cross sections as function of A, Z and E is discussed and explained in terms of a Coulomb-modified strong-absorption model. Finally, optical potentials which fit simultaneously low-energy View the MathML sourceHe observables for E<0 as well as for E>0 are used to assess the reliability of extracting Coulomb modified View the MathML source nuclear scattering lengths directly from the data. The relationship between different kinds of scattering lengths is discussed and previously published systematics of the View the MathML source nuclear scattering lengths is updated.