Microscopic distorted-wave approximation study of low-energy nucleon scattering from 89Y.

Abstract

New differential cross section data for inelastic neutron scattering to the first three excited states of $^{89}\mathrm{Y}$ at ${E}_{\mathrm{n}=11}$ MeV are studied using a microscopic folding model and three energy- and density-dependent effective interactions. Results are also presented for the corresponding transitions in inelastic proton scattering at 14.7, 24.5, and 61.2 MeV. Transition densities were obtained from a combination of available inelastic electron-scattering data and theoretical considerations. The calculated angular distributions provide a reasonable description of the experimental data for the predominantly quadrupole (\ensuremath{\Delta}J=2), ${(1/2}^{\mathrm{\ensuremath{-}}}$\ensuremath{\rightarrow}${(3/2}^{\mathrm{\ensuremath{-}}}$ (${E}_{x}$=1.509 MeV) and ${(1/2}^{\mathrm{\ensuremath{-}}}$\ensuremath{\rightarrow}${(5/2}^{\mathrm{\ensuremath{-}}}$ (${E}_{x}$=1.745 MeV) transitions in the target. It is shown that the neutron scattering data for these two transitions are sensitive to the shape differences in the transition densities suggested by theory and electron scattering. The theoretical results for the predominantly \ensuremath{\Delta}J=5, ${(1/2}^{\mathrm{\ensuremath{-}}}$\ensuremath{\rightarrow}${(9/2}^{+}$ (${E}_{x}$=0.909 MeV) transition significantly underestimate the proton and neutron scattering cross sections at ${E}_{\mathrm{p}<25}$ MeV and ${E}_{\mathrm{n}=11}$ MeV, but provide a reasonable description of the proton scattering data for this transition at ${E}_{\mathrm{p}=61.2}$ MeV.