Relative Absorption of 10 Mc/sec Longitudinal Sound Waves in a Superconducting Polycrystalline Tin Rod

Abstract

The relative absorption of 10 Mc/sec sound pulses has been studied between 1.5°K and 3.73°K (the transition temperature) in superconducting polycrystalline tin and above 3.73°K to about 4.2°K in the normal metal. Above the transition the absorption was heavy, but below it, the absorption decreased considerably as the temperature was lowered. It was possible to estimate how the minimum value of the absorption coefficient (which differed from the true value by an undetermined constant equal to the absorption coefficient at the absolute zero of temperature) varied as a function of temperature but no success has yet been achieved in correlating this quantitatively with existing theories of superconductivity or of absorption of sound in metals at low temperatures.