Abstract

J. Low Temp. Physics (2002) 126 (1-2) 591-596.

Narrow-Angle Beams of Strongly Interacting Phonons

C.D.H. Williams, A.A. Zakharenko, and A.F.G. Wyatt

School of Physics, University of Exeter, Exeter, EX4 4QL (UK).

(Submitted 30 June 2001)

We demonstrate that narrow-angle phonon pulses of low energy phonons in liquid ⁴He are strongly interacting and rapidly come into equilibrium within a narrow cone in momentum space. The effect of collimation on such a system is to strongly reduce the axial phonon flux. This gives a method of separating high and low energy phonons.

Keywords: liquid helium, phonons.
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