Phase-shift analysis of neutron-209Bi scattering and its comparison to neutron-208Pb scattering.

Abstract

Published n${\mathrm{\ensuremath{-}}}^{209}$Bi elastic differential cross-section, analyzing power, and total cross-section data in the energy range from 1.5 to 14 MeV were analyzed via a phase-shift analysis in order to find out whether these data show similar, unexplained resonance structures as observed recently for n${\mathrm{\ensuremath{-}}}^{208}$Pb scattering. Although the n${\mathrm{\ensuremath{-}}}^{209}$Bi and n${\mathrm{\ensuremath{-}}}^{208}$Pb data are very similar, some of the phase shifts are quite different for the two systems. Only one resonancelike structure was observed for n${\mathrm{\ensuremath{-}}}^{209}$Bi scattering in the excitation energy range from 9 to 18 MeV compared to eleven in the n${\mathrm{\ensuremath{-}}}^{208}$Pb system, implying that n${\mathrm{\ensuremath{-}}}^{209}$Bi data are probably more suitable than the classical n${\mathrm{\ensuremath{-}}}^{208}$Pb system for detailed mean-field analyses approached through dispersion-relation optical models.