Thermodynamic velocity and dispersion of first sound in liquid helium near the lambda transition

✍ Scribed by Fernanda Miguélez; Oscar Cabeza; Carolina Torrón; Luisa Segade; Alberto Pomar

• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 247 KB
• Volume: 34
• Category: Article
• ISSN: 0011-2275
• DOI: 10.1016/s0011-2275(05)80075-x

✦ Synopsis

We extend the functional form of thermodynamic velocity of first sound in liquid helium near X transition, at different pressures, by using the heat capacity (as proposed by Chase[l], Pippard[2] and G. Ahlers[3]) to reach the hydrodynamic region ( I t [ = [ T-T× [ > 10 mK). For heat capacity we use both descriptions, logarithmic and power-law. These results are compared with experimental data obtained in resonant cavities for 20/~K< ] t I < 1 mK and frequencies co, less than 7.5 KHz. In adition, these results are used to calculate the critical dispersion in the phenomenological theory of Ferrell and Bhattacharjee[4], based on dynamic scale theory. A strikingly good agreement with experimental results is found.