Structure-factor measurements in He4 as a function of density

Measurements of the structure factor $S(k)$ for $^{4}\mathrm{He}$ are reported as a function of pressure at 1.67, 2.20, and 4.24 K from saturated vapor pressure to 25 atm. The liquid structure factor is seen to sharpen and increase in amplitude with an increase in pressure at each of the temperatures studied. Comparison is made to previous results obtained by the technique of neutron scattering as well as to the theoretical predictions of Chang and Campbell and of Whitlock et al. The pair correlation function $g(r)$ is obtained from the liquid structure factor by means of a Fourier transform, and comparison is made to theoretical predictions.