Superfluidity in a Dilute Bose Gas

Superfluid ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ films adsorbed on porous Vycor glass have been studied in the low-density limit where the superfluid interparticle spacing is more than an order of magnitude greater than the atomic hard-core diameter. For the lowest transition temperatures observed, the influence of critical fluctuations near $T_c$ is much reduced and a range of crossover to behavior more characteristic of the dilute Bose gas is observed.