Neutron diffraction study of long-range interactions in gaseous krypton

The low-Q part of the static structure factor S(Q) of has been derived at five low densities and room temperature by a small-angle neutron diffraction measurement and a careful treatment of experimental corrections. From the data the small-Q dependence of the Fourier transform c(Q) of the direct correlation function c(r) has been obtained and has allowed the first accurate experimental determination of the long-range three-body Axilrod-Teller potential strength in a classical fluid.