Superfluidity of 4He film adsorbed on 47 Angst pores

The superfluid of 4He films adsorbed on uniform straight pores 47 Angst in diameter has been studied using a torsional oscillator in order to investigate the nature of the superfluid transition of the film formed in several nanometer pores. The results show that the film in the pore is certainly superfluid above 1.5 layers. The temperature dependence of the superfluid density below the superfluid transition temperature is not so sharp compared with that expected by the Kosterlitz-Thouless transition. This behavior is qualitatively explained by the strong confinement of the vortex pair