The dynamic pair distribution function of superfluid $^{4}$He

We present precision neutron scattering measurements of the spatial and time correlations between atoms in liquid $^{4}$He using dynamic pair distribution methods. As the Bose-Einstein condensate (BEC) sets in below the superfluid transition temperature $T_{\lambda}$, we observe clear changes in the local environment of the atoms. These local changes are investigated beyond the first coordination shell. We also test our observations against recent classical and ab-initio molecular dynamics simulations in which the local configurational excitations in the atomic connectivity network was found to be the elementary excitation in some liquid metals.