Effect of disorder on the critical temperature of a dilute hard-sphere Gas

We have performed path integral Monte Carlo calculations to determine the effect of quenched disorder on the superfluid density of a dilute 3D hard-sphere gas. The disorder was introduced by locating hard cylinders randomly inside the simulation cell. Our results indicate that the disorder does not strongly affect the superfluid critical temperature. There is a reduction of rho(s)/rho with increasing disorder and with excluded volume for similar disorders and a possible change of universality class (as evidenced by the correlation length exponent) at high disorder. Comparison to experiments of helium in Vycor is made.