Target-boundary scattering and resonant detection and classification

Several of the geometric and physical parameters of an elastic target may be determined from its resonance spectrum. Resonance scattering theory has shown that the form function for the resonance spectrum may be obtained by subtracting the form function for background scattering from the total form function. Although background form functions for free field scattering are well known, background form functions for scattering from targets near a planar boundary are not. In this paper, an interacting background form function is defined and a null field T-matrix formalism is used to calculate the resonance spectrum of fluid loaded elastic spherical shells near planar penetrable sediment boundaries. Results are compared with free field results to determine the ability of the interacting background to isolate free field resonances, to identify some of the effects of target-boundary scattering on the resonance spectrum, and the ability to determine target parameters