The neutron dispersive optical model potential that was developed previously from an analysis of extensive data on the neutron${\mathrm{-}}^{40}$Ca system is adapted to the neutron${\mathrm{-}}^{40}$Ar system by adjusting the central depth of the local equivalent of the Hartree-Fock-type potential. The n${\mathrm{-}}^{40}$Ar data for this adjustment are the total cross section for 11<E<40 MeV and the centroid energy for the observed single-particle and single-hole states of the valence shells. The resulting potential for n${\mathrm{-}}^{40}$Ar yields good predictions for the particle-hole gap for the valence shells and for the energy-averaged s-wave and p-wave scattering functions in the resonance region. However, it gives a poor prediction for the total cross section from 2 to 11 MeV. A similar discrepancy was observed earlier for ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$. A parity dependence in the surface imaginary potential is suggested from a more careful examination of the s-wave and p-wave scattering functions for ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ar}$; that parity dependence gives a good prediction of the total cross section for 2 to 11 MeV.

• Received 27 August 1990

DOI:https://doi.org/10.1103/PhysRevC.44.657