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The breakdown of superfluidity in liquid 4He : an experimental test of Landau's theory.

Allum, D. R. and McClintock, Peter V. E. and Phillips, A. and Bowley, R. M. (1977) The breakdown of superfluidity in liquid 4He : an experimental test of Landau's theory. Philosophical Transactions of the Royal Society of London A, 284 (1320). pp. 179-224. ISSN 0264-3820

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Abstract

A single pulse time of flight technique has been used to determine the drift velocity v of the negative ions injected into liquid 4He from a field emission source. Measurements of v as a function of temperature T, pressure P and electric field E are presented within the range: 0.29 < T < 0.5 K; 21 x 10^5 < P < 25 x 10^5 Pa; 1 < E < 300 kV/m. The experimental results are in good agreement with Landau's theory of superfluidity. The data are used to demonstrate the inapplicability of two theories of super critical dissipation: by Takken, based on an assumption of coherent roton emission; and by Bowley and Sheard, based on the assumption of incoherent single-roton emission. The results are, however, shown to be in excellent agreement with Bowley and Sheard's incoherent two-roton theory, and the data are used to derive a numerical value of the matrix element. characterizing two-roton emission. The surprising absence of the single-roton emission process is discussed, and an upper bound is placed on the relevant matrix element.

Item Type: Article
Journal or Publication Title: Philosophical Transactions of the Royal Society of London A
Subjects: Q Science > QC Physics
Departments: Faculty of Science and Technology > Physics
ID Code: 32514
Deposited By: Professor P. V. E. McClintock
Deposited On: 12 Apr 2010 12:01
Refereed?: Yes
Published?: Published
Last Modified: 26 Jul 2012 17:11
Identification Number:
URI: http://eprints.lancs.ac.uk/id/eprint/32514

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