An analysis of partial wave scattering coefficients and the interpretation of resonances and background in scattering from elastic targets

Abstract

Bistatic angular distributions and backscattered form functions can be, represented as a partial wave series where the angular contribution can be. written in terms of spherical harmonics or some other suitable angular function. It is possible to represent elastic, rigid, and solid targets in such a representation. The appropriate background (in partial wave space) can be subtracted from some elastic target and a resonance can be isolated. This is usually done by assuming a rigid or a soft background for elastic: solids or thin shells and leads to a residual response that, under appropriate conditions, can manifest a resonance. Often, however, neither a rigid nor a soft background is suitable. This can be established by examining the residual partial wave coefficients, which, in the event of a poor choice of background, will lead to a mix of several partial waves at resonance. On the other hand, for a good background choice, a predictable mix of partial wave coefficients will be observed. When a suitable background has been chosen, then the partial wave analysis allows one to characterize the resonance.