Shear acoustic response of the superfluid helium-3 Original Research Article

Transverse acoustic response in the B-phase of superfluid 3He was measured by using an AC-cut quartz transducer at a pressure of 17.0 bar. The measurements were performed by a CW bridge method at a frequency of about 9.6 MHz utilizing a quadrature hybrid and a high-frequency lock-in amplifier. By sweeping frequency around the resonance frequency of the transducer, in-phase and quadrature responses of the resonance were obtained from the output of the high-frequency lock-in amplifier. The change of the ΔQ−1 and the resonance frequency Δf0 which were proportional to the real and the imaginary part of the transverse acoustic impedance of superfluid 3He were obtained separately.