Liquid Structure Factor ofHe4by X-Ray Scattering at Small Momentum Transfer

Abstract

The liquid structure factor of helium-4 has been determined in the momentum-transfer range 0.2 to 0.8 ${\mathrm{\AA }}^{-1\mathrm{}}$. At 0.32 K the structure factor exhibits a gentle but decided change of slope near 0.4 ${\mathrm{\AA }}^{-1\mathrm{}}$ in qualitative agreement with certain theoretical predictions. Below 0.4 ${\mathrm{\AA }}^{-1\mathrm{}}$ the liquid structure factor agrees with that deduced from the Bijl-Feynman dispersion relation. At 4.99 K and 680 mm pressure we have shown that helium gas is distinctly nonideal.