Optical model analysis of 200 MeV p

Abstract

Differential cross sections and analyzing powers are presented for $^{16}$O(p\ensuremath{\rightarrow},p${)}^{16}$O elastic scattering at ${E}_{\mathrm{p}=200}$ MeV, extending over a large range of momentum transfer (up to q\ensuremath{\sim}6 ${\mathrm{fm}}^{\mathrm{\ensuremath{-}}1}$). The data were analyzed in the framework of the nonrelativistic optical model. In addition to standard Woods-Saxon potentials, nonstandard radial shapes for the central and the spin-orbit potentials were investigated. The data are not adequately described over the entire angular range using a Woods-Saxon real central potential, but two distinct parametrizations (not simply related by the usual discrete or continuous parameter ambiguities which maintain a rough phase-shift equivalence) were found which provide a far superior representation. The similarity in the angular distributions given by these two potentials can be attributed to the fact that the non-spin-flip partial-wave scattering amplitudes ${a}_{L}$ differ by only a simple rotation in the complex ${a}_{L}$ plane. This rotation has a negligible effect on the predicted cross section and the analyzing power angular distributions, but leads to sizable differences in the predicted spin-rotation function Q(\ensuremath{\theta}).