A method has been developed for making ultrasonic attenuation measurements in a large sample by means of a solid buffer rod temporarily bonded to the sample. A piezoelectric transducer is permanently bonded to the other end of the buffer rod. The ratios of the amplitudes of certain echoes are used to find the ultrasonic attenuation in the sample and the reflection coefficient at the buffer-sample interface at various frequencies across the band of the transducer. The echo-amplitude ratios are not affected by operating the transducer away from its resonant frequency, because none of the echoes considered arise from reflections at the buffer-transducer interface. A numerical analysis of the echo amplitudes is presented in which the reflection coefficient is assumed constant and the ultrasonic attenuation is taken as a power of the frequency. Experimental data are given on shear waves in a glass buffer rod on a fused-silica sample. The reflection coefficient varies little while the ultrasonic attenuation increases with frequency, fluctuating near 30 MHz.
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Emmanuel P. Papadakis (1968) studied this question.