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Details of Grant 

EPSRC Reference: GR/S24855/01
Title: AnisotropicPhonon Systems (Visiting Fellowship for Professor I N Adamenko)
Principal Investigator: Wyatt, Professor A
Other Investigators:
Researcher Co-Investigators:
Project Partners:
Department: Physics
Organisation: University of Exeter
Scheme: Standard Research (Pre-FEC)
Starts: 12 February 2003 Ends: 11 June 2004 Value (£): 22,575
EPSRC Research Topic Classifications:
Quantum Fluids & Solids
EPSRC Industrial Sector Classifications:
No relevance to Underpinning Sectors
Related Grants:
Panel History:  
Summary on Grant Application Form
Anisotropic phonon systems in an isotropic medium behave in a remarkable way: high energy phonons can be created from low energy phonons. This astonishing result was discovered from experiments on quantum evaporation from liquid helium. In a collaboration with Professor Adamenko we have develc a model with which we can consider the various aspects of anisotropic phonon propagation. This new physics arises because we create excitations that only occupy a small solid angle in momentum space and this coupled with strongly anisotropic interactions makes it qualitatively different to the usual isotropic case. One of the more spectacular predictions is that suprathermal densities of high energy excitations are formed, densities more than 30 times those in isotropic systems. This application is for funds to continue the joint work with Professor Adamenko and his group. We will first make detailed calculations of the high energy phonon interaction rates. These will then be used to quantitatively evaluate the various predictions of the model. Our goal is to calculate how the spect of the phonons develops in space and time as the pulse propagates. We need to understand how high energy phonons are created so far in front of the heater < to calculate the spectrum of phonons that are involved in quantum evaporation. We also plan to analyse the interactions of rotons with interfaces using our new model of rotons in liquid helium.
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Organisation Website: http://www.ex.ac.uk