We are grateful to Prof. H. Medwin for useful discussions in our earlier attempts at building resonators and his continued interest in our efforts to move on to an improved implementation; to Dr. K. Commander for valuable input on the bubble calculation algorithm; to Nick Hall-Patch for developing the resonator electronics; and to undergraduate co-op students Shinya Matsueda and Norman Laman as well as high school students Grant Foster and Adam Sera for their assistance in the implementation and data processing. This work received support from the U.S. Office of Naval Research.
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