The Kapitza Resistance Between Copper and He-3

The Kapitza resistance R-K between copper and He-3 has been measured at low pressure in a guarded cell in the temperature range 0.05-0.5 K. An extreme sensitivity to surface damage was observed. For an annealed, electropolished surface R-K agreed within a factor of two with the acoustic mismatch theory below approximate to 0.1 K. It was also noted that R-K between copper and liquid He-3 was identical to RK between copper and an adsorbed He-3 film. The data are compared with several mechanisms proposed theoretically to account for R-K.