Observation of a Profile on a Superfluid Helium Film on a Rotating Substrate

Simultaneous measurements of the thickness at two locations of a He II film adsorbed on a rotating substrate have been made. From the thickness difference we deduce that for $T>\mathrm{}2.1\mathrm{}$ K the film has a solid-body velocity field, whereas for $T=1.23\mathrm{}$ K the velocity is zero until the linear velocity of the substrate exceeds the translational critical velocity of the film.