Cavitation Density Of Superfluid Helium-4 Around 1 K

Using an optical interferometric method, the cavitation density of bulk superfluid helium at T = 0.96 K is measured and found to rho(cav) = 0.1338 +/- 0.0002 g cm(-3). A well-established equation of state for liquid helium at negative pressures converts this to the cavitation pressure P-cav = -5.1 +/- 0.1 bars. This cavitation pressure is consistent with a model taking into account the presence of quantized vortices, but disagrees with previously published experimental values of P-cav.