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Our research involves studies of the solid/super fluid 4He interface for multilayer solid 4He on graphite using both fourth sound and heat capacity techniques. In the case of fourth sound the effects of small concentrations of 3He on the interface susceptibility have been measured. Heat capacity measurements determined an upper limit for the criticality of the layering transitions.

The acoustic-scattering corrections of several types of superleaks have been measured, providing information about inertial drag effects in the Row of superfluid He. The porous media which have been studied include A1203 packed powder, Grafoil, and Grafoil foam. The frequency dependence of the acoustic-scattering correction was measured for the Grafoil media.

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