Answers are grounded in this paper and cite their sources.
We report new high precision data on the velocity of second sound close to the lambda transition of 4 He at the saturated vapor pressure. The second sound wave is detected by a powdered salt pill of copper ammonium bromide in direct contact with the liquid helium. With a thermometer noise of ≤10 -10 K/√Hz we are able to make measurements in the linear regime to within 20 nanokelvin of the lambda point. We have obtained reasonable agreement with renormalization group theory predictions after allowance for the effect of gravity. The results are also compared with previous experiments.
No takes yet. Share an insight, caveat, or question.
Adriaans et al. (1994) studied this question.
Synapse has enriched 10 related papers. Consider them for comparative context: