A High-Speed Ultrasonic Sing-Around System

An ultrasonic sing-around system has been developed that allows the measurement of the velocity of sound in a sample to an accuracy of a few parts in 104 in a period of 10 μs. A facility is also provided to store a succession of measured sing-around periods. This approach enables the continuous measurement of the velocity of sound in materials undergoing rapid changes of thermodynamic parameters such as temperature, magnetic field, or pressure to be achieved. As an example, the magnetic-field variations of the velocity of sound in a magnetic gadolinium-yttrium alloy are reported.