Fluid-structure-factor measurements inHe4for5.5<~T<~7.0K

We report precise measurements of the structure factor $S\left(k\right)\mathrm{}$ as a function of the momentum transfer $k$ for ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ at $T=5.5\mathrm{} \mathrm{and} 6.5$ K in the density range $10\lesssim \rho \lesssim 155$ kg/${\mathrm{m}}^3$. No theoretical predictions that can be tested against the data are available. The recent theoretical work by Bruch et al. at $T=7.0\mathrm{}$ K, $\rho =69.6\mathrm{}$ kg/${\mathrm{m}}^3$ is in only limited agreement with our experimental data at $T=7.0\mathrm{}$ K, $\rho =69.0\mathrm{}$ kg/${\mathrm{m}}^3$.