Back-Angle Elastic Scattering of 14.6-Mev Neutrons from Aluminum, Copper, and Zirconium

Differential elastic scattering cross sections have been measured for 14.6-Mev neutrons on aluminum, copper, and zirconium in 5^∘{} steps from 85^∘{} to 155^∘{}. The copper and zirconium angular distributions are in good agreement with optical-model calculations by Bjorklund and Fernbach, who employ a spin-orbit coupling term in their potential. The aluminum differential cross sections are systematically higher than the predictions at the back angles, indicating that the Bjorklund-Fernbach optical-model parameters which fit the medium and heavy elements are not as successfully applied to an element as light as aluminum.