Excitations in superfluid 4He beyond the roton

sigh-energy resolution inelastic neutron scattering data on excitations in superfluid and normal He-4 at SVP at wave vectors Q beyond the roton, 2.0 less than or equal to Q less than or equal to 4.0 Angstrom(-1), are presented. The narrow energy resolution of these measurements reveals that the energy of the elementary excitation comes up to twice the roton energy, 2 Delta, at Q = 2.8 Angstrom(-1) and the energy remains constant at 2 Delta between Q 3.0 Angstrom(-1) and the end point of the dispersion curve at Q = 3.6 Angstrom(-1) The width of the peal; is also unobservably small from Q = 2.8 Angstrom(-1) out to the end point, W = 2 Gamma < 20 mu eV.