Dynamics of liquid He-4 in Vycor

Using inelastic neutron scattering, we have observed well-defined phonon-ro ton (p-r) excitations in superfluid He-4 in Vycor over a wide wave-vector r ange, 0.3 less than or equal to Q less than or equal to 2.15 Angstrom(-1). The p-r energies and lifetimes at all temperatures an the same as in bull; liquid He-4. However, the weight of the single p-r component does not scale with the superfluid fraction rho(S)(T)/rho as it does in the bulk, In part icular, we observe a p-r excitation above T-c = 1.952 K, where p(S)(T) = 0 in Vycor. This suggests, if the p-r excitation intensity scales with the Bo se condensate, that there is a separation of the Bose-Einstein condensation temperature and the superfluid transition temperature T-c of He-4 in Vycor .