Viscoelastic behavior of helium at 39 K and 114 bar

The dynamic structure factor S(k,{ω}) of dense helium at 39.3 K ({}8Tc) and 114 bar is measured by inelastic neutron scattering for wave numbers 3{≤}k{≤}24 nm^-1. In contrast to dense noble-gas fluids at T2Tc, the present S(k,{ω}) can be described completely by the viscoelastic model, in which S(k,{ω}) is determined for each k by its zeroth, second, and fourth frequency moment and by one decay rate (that of the microscopic momentum flux).