Experiments on the Scattering of Light by Liquid Helium
The Malvern-Birmingham groups have conducted light scattering experiments on liquid helium in a number of different regimes: Rayleigh and Brillouin scattering from superfluid mixtures of 3He-4He,1 from normal and superfluid 4He,2 second-order Raman scattering from 4He above the λ-point,3 and total intensity measurements close to the λ-line.4 This paper describes the spectroscopic equipment used in recent studies and the results of attenuation and velocity measurements of first sound close to the λ-line at elevated pressure and a frequency close to 1 GHz. These latter results relate well in their general form with previous measurements at SVP and show a velocity minimum and attenuation maximum several millidegrees below the λ-point.
KeywordsLiquid Helium Stimulate Brillouin Scattering Free Spectral Range Velocity Minimum Attenuation Maximum
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- E.R. Pike, J. Physique 33, C25 (1972).Google Scholar