Low-temperature superfluid density in a restricted geometry

The temperature dependence of the superfluid density for liquid helium contained in a restricted geometry has been studied using fourth-sound, persistent-current, and oscillating U-tube techniques. Particular emphasis is given to the temperature range below 1 K. At the lowest temperatures the effective superfluid density becomes a linear function of temperature; this behavior is in contrast to bulk helium where a small T4 temperature dependence is expected.