Propagation of nonlinear waves of first sound in liquid helium
Sibel'din N.N., Stopachinskii V. B., Tsvetkov V. A., Etien B.
It was determined that the pulses of first sound, [Kabetskaya etal. Sov. Phys. Dokl. 24, 37 (1979)] which was excited in liquid helium by optical pumping of germanium, are low-intensity shock waves. The velocity of the sound pulse as a function of its amplitude was measured.