Analysis of total neutron-nucleus cross sections using relativistic impulse approximation.

Abstract

We have used the relativistic impulse approximation (RIA) to study the newly measured neutron total cross section data for [sup 208]Pb, [sup 90]Zr, and [sup 40]Ca. In particular, we are interested in what we can learn from the RIA in order to build up a phenomenological optical potential. A complete set of scattering observables would be required in order to study the details of the neutron-nucleus interaction. In the absence of any such data at intermediate energy, the present study of total cross sections provides useful preliminary information on the isovector part of a generalized nucleon-nucleus interaction. We used the [ital NN] amplitude calculated by McNeil, Ray, and Wallace (MRW) and the relativistic Love-Frany [ital NN] amplitude developed by Murdock and Horowitz (MH). We found that the use of MH's amplitude in the RIA gives a good description to the neutron total cross section from 200 to 400 MeV, while the use of MRW's amplitude provides a good description from 500 MeV and above. The energy dependence of the volume integrals of the total optical potential is consistent from both calculations, but there is a large difference in the energy dependence of the volume integral of the isovector part ofmore » the potential.« less