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Kinetic energy of He atoms in liquid $^4$He-$^3$He mixtures

R. Senesi·C. Andreani·A. L. Fielding·J. Mayers·W. G. Stirling
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Abstract

Deep Inelastic Neutron Scattering measurements on liquid $^3$He-$^4$He mixtures in the normal phase have been performed on the VESUVIO spectrometer at the ISIS pulsed neutron source at exchanged wavevectors of about $q \simeq 120.0$ Å$^{-1}$. The neutron Compton profiles J(y) of the mixtures were measured along the $T=1.96$ K isotherm for $^3$He concentrations, $x$, ranging from 0.1 to 1.0 at saturated vapour pressures. Values of kinetic energies, $ $, of $^3$He and $^4$He atoms as a function of $x$, $ (x)$, were extracted from the second moment of J(y). The present determinations of $ (x)$ confirm previous experimental findings for both isotopes and, in the case of $^3$He, a substantial disagreement with theory is found. In particular $ (x)$ for the $^3$He atoms is found to be independent of concentration yielding a value $ _3(x=0.1)\simeq 12 K $, much lower than the value suggested by the most recent theoretical estimates of approximately 19 K .

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R. Senesi, C. Andreani, A. L. Fielding, J. Mayers, W. G. Stirling. 2003-10-24. Kinetic energy of He atoms in liquid $^4$He-$^3$He mixtures. https://doi.org/10.1103/physrevb.68.214522

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