Reduction of the Superfluid Fraction of 3He in Sintered Silver

We have measured the superfluid density of 3He liquid confined within the pores of a silver sinter plug. The silver was of nominal 70 nm size, and was packed to 54% of solid density. The mean pore size as measured was ?200 nm. The plug was mounted on a torsional oscillator, and the superfluid density can be measured by studying the decrease of the resonant period. We have measured the pressure and temperature dependence of the period shift and find that the superfluid density is suppressed to ?14% at 0 bar and is ?53% of its bulk value at 29 bar. There is substantial temperature dependence even at the lowest values of T/Tc(?0.25) achieved in these experiments.