ASA 127th Meeting M.I.T. 1994 June 6-10

5aUW2. The resonance scattering theory and acoustic transients.

Herbert Uberall

Dept. of Phys., Catholic Univ. of America, Washington, DC 20064

Larry Flax conceived the idea that provided the impetus for the development of what is now called the acoustic resonance scattering theory (RST), as described in Chap. 4 of Acoustic Resonance Scattering, edited by H. Uberall (Gordon and Breach, New York, 1992). The explicit development of this theory employed an approach used in the quantum mechanical theory of nuclear scattering, the so-called Breit--Wigner resonance theory. The interplay between target resonances and transient signals, hardly accessible to nuclear scattering experiments, is easily observed in acoustics and now forms the basis of experimental resonance studies that are most vigorously being carried out in France (see the above reference, or N. Gespa, La Diffusion Acoustique (CEDOCAR, Paris, 1987). Pulses of long duration generate surface waves that carry out multiple circumnavigations of the target, their overlap leading to final transients or ringing of individual resonances (Carbo-Fite, Veksler, Maze, Ripoche). Short pulses combine the ringing of many resonances, the corresponding circumferential waves synthesizing surface-wave pulses in the fashion of beats, as demonstrated by Werby. For the interpretation of time domain experiments, a methodology is developed that is based on RST for a unique interpretation of results with a variety of target. [Work supported by ONR.]