Three-Phonon Processes in Second Sound, Poiseuille Flow, and Thermal Conduction in Solid 4He
Poiseuille flow and second sound have provided for solid 4He a body of evidence concerning τN-1, the N-process scattering rate, τN-1 has also been inferred from the thermal resistivity of isotopic point defects. However, the various estimates of τN-1 differ both as regards temperature dependence and the absolute magnitude . Recent Poiseuille flow experiments of Golub et al  point to differences in dislocation concentration in the helium crystals as a source for these disparities. In their analysis, allowing for dislocations increases the overall estimate of τN-1 and changes its apparent temperature dependence from (T/θ)3 to (T/θ)5. We have looked again at the pulse propagation of second sound in solid 4He to see what evidence there might be for the effects of dislocations.
KeywordsPoiseuille Flow Pulse Profile Primary Pulse Phonon Wave Vector Helium Crystal
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