Unified optical-model approach to low-energy antiproton annihilation on nuclei and to antiprotonic atoms
✍ Scribed by C.J. Batty; E. Friedman; A. Gal
- Publisher
- Elsevier Science
- Year
- 2001
- Tongue
- English
- Weight
- 182 KB
- Volume
- 689
- Category
- Article
- ISSN
- 0375-9474
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✦ Synopsis
A successful unified description of p nuclear interactions near E = 0 is achieved using a p optical potential within a folding model, V opt ∼ v * ρ, where a pp potential v is folded with the nuclear density ρ. The potential v fits very well the measured pp-annihilation cross sections at low energies (p L < 200 MeV/c) and the 1s and 2p spin-averaged level shifts and widths for the pH atom. The density-folded optical potential V opt reproduces satisfactorily the strong-interaction level shifts and widths over the entire periodic table, for A > 10, as well as the few low-energy p-annihilation cross sections measured on Ne. Both v and V opt are found to be highly absorptive, which leads to a saturation of reaction cross sections in hydrogen and on nuclei. Predictions are made for pannihilation 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 p-4 He observables for E < 0 as well as for E > 0 are used to assess the reliability of extracting Coulomb modified p nuclear scattering lengths directly from the data. The relationship between different kinds of scattering lengths is discussed and previously published systematics of the p nuclear scattering lengths is updated.