X-Ray Scattering from LiquidHe4

The liquid structure factor of ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ has been measured in the momentum transfer range from 0.133 to 1.125 ${\mathrm{\AA }}^{-1\mathrm{}}$ and a variety of temperatures from 0.38 to 4.6 K. At the lowest temperature, the structure factor demonstrates a gentle change of slope in the momentum transfer region near 0.4 ${\mathrm{\AA }}^{-1\mathrm{}}$. Values for the first and second moments of the pair correlation function are obtained at 1.45 and 3.30 K. We compare our results with recent neutron and x-ray work and also with recent theories.