A New Automatic Method for Measuring Sound Velocity with High Resolution

Modification of the well known continous wave r esonator method for measuring sound velocity results in a further increased resolution and allows automation of the measurement. Because of very low input power requirements this system allows measurements at temperatures as low as 15 mK without heating the sample. Limits to resolution are imposed mainly by the quality f actor of the acoustic resonator and the glassy nature of the bonding agent by which the transducers are glued onto the sample. Examples of measurements performed on z-cut Quartz between 0.015 K and 5 K are given.