Detection of Vortices in Superfluid He in the T=0 Limit Using Charged Vortex Rings

We describe the experiment to study the dynamics of quantized vortex lines in superfluid at temperatures down to 40 mK, i.e., without any normal component. This was achieved by monitoring the trapping of small charged vortex rings by an array of rectilinear vortex lines produced by rotating the cryostat. The design of the experimental cell is described. Our first observations of the response of the superfluid in the T =0 limit to starting and stopping rotation are presented.