The velocity of second sound near the lambda transition in superfluid4He

✍ Scribed by M.J. Adriaans; D.R. Swanson; J.A. Lipa

• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 163 KB
• Volume: 194-196
• Category: Article
• ISSN: 0921-4526
• DOI: 10.1016/0921-4526(94)90696-3

✦ Synopsis

We report new high precision data on the velocity of second sound close to the lambda transition of 4He 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 < 10-1°K/v/-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.