Precession of a single vortex line in superfluid B3

This paper reports the discovery of a new vortex phenomenon in superfluid B3. A single filament of quantized vortex line precesses as a solid body around a wire extending along the axis of a cylinder. The precession frequency equals the angular velocity of the apparatus at which the presence of a single quantum of circulation minimizes the systems free energy. The period of precession is related to the circulation quantum and the dimensions of the apparatus. Thus a measurement of the precession period is an accurate determination of the quantum unit. We find =(1.0200.03)h/2m3, where m3 is the mass of the He3 atom.