Measurements of the superfluid transition in helium by means of a vibrating reed

A relatively simple method is presented that has been used in an undergraduate experimental course for observing the superfluid transition in ⁴He. The experimental technique consists of submerging a vibrating reed in liquid helium and observing the changes in frequency and damping (energy dissipation) as the temperature is regulated above and below the superfluid transition. The results of the measurements are interpreted by means of a simplification of the acting hydrodynamic forces, and it is seen that most of the relevant physics is well described by the approximations.