Transmission of High-Frequency Phonons through a Solid-Liquid-Helium Interface

Abstract

Heat-pulse experiments at 1.3 K show that the conversion of ballistic high-frequency phonons in a solid into second sound in superfluid helium can be used to study the transmission coefficient of the phonons through the interface. The transmission coefficients for longitudinal and transverse phonons in silicon are found to be equal for heater temperatures between 10 and 20 K.