Unusual doppler shift of fourth sound in3He-4He mixture.

✍ Scribed by N. Gov; A. Mann; Y.A. Nepomnyashchy; M. Revzen

• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 141 KB
• Volume: 194-196
• Category: Article
• ISSN: 0921-4526
• DOI: 10.1016/0921-4526(94)90612-2

✦ Synopsis

Independent macroscopic motions and several sounds in a superfluid liquid implies unusual effects in the Doppler shift which becomes a nonkinematic phenomenon. As it was recently shown [2] the Doppler shift of fourth and first sounds is characterized by a nontrivial temperature dependence. Moreover there appears a special outstripping effect: the center of the spreading sound moves faster than the flowing superfluid part of the liquid itself. Here we investigate the anomaly of the Doppler shift of the fourth sound in the mixture aHe-4He. We show that in the presence of the admixture 3He the outstripping effect substentialy increases, so that it becomes more accessible to experimental observation. We analyse also the physical origin of the phenomenon which is different in the case of pure 4He and of mixture 3He-4He.