Optical Model Evidence for Surface Absorption of Neutrons

Abstract

Data-matching with the complex square well model for neutron scattering suggests that the imaginary part of the potential should be largest at the nuclear surface; such an effect is also in accord with present physical pictures of the interaction. However, when a diffuse edge is attached to the model and the other parameters are changed to provide experimental agreement, the need for surface absorption appears diminished. To investigate further, cross sections resulting from a surface-absorbing and a uniformly absorbing potential, both with a diffuse edge, are calculated and compared. The results differ considerably less from each other than from the data, but the strength of absorption is more nearly independent of mass number when it is concentrated near the surface.