No abstract

Neutron-scattering cross-section data between 0.1 and 3.0 MeVforU, Th,Bi, Pb, Au, W,and Ta have been fitted using a local, spherical, spin-dependent optical potential with a minimum number of parameters. Total cross sections and differential elastic angular distributions, corrected to include compound elastic scattering, are used. With the ''entrance-channel" parameters thus determined, the Hauser-Feshbach statistical model gives reasonable predictions of the cross sections for inelastic scattering of neutrons by U 238 , Th 232 , Bi 209 , Pb 208 , Au 197 , W 184 , and Ta 181 . The latitude in fitting entrance-channel data allowed by the optical-model parameters is sufficient to mask effects arising from nonlocality, deformation, and width distributions. To a very high degree, this relatively simple model is shown to be

Earlier work on the inelastic scattering of neutrons by heavy nuclei in the 1-4-MeV region is extended to the lighter elements Fe and Al. Calculations using a diffuse-edged optical-model potential defined by six parameters, including a spin-orbit term, are sufficient to describe the total and differential elastic scattering. When the Hauser-Feshbach formalism is applied, inelastic-scattering calculations consistent with the above model fit the experimental data reasonably well. The relationship to models requiring additional parameters is discussed.

Low-energy electron energy loss spectroscopy (LEELS) has been used to study the electronic structure of margarite. The results show that the electronic structure of margarite is determined principally by local atomic arrangement and also the usefulness of LEELS as a powerful technique to investigate the depth profiling of the electronic structure of a material.

No abstract