| Abstract
| - We present neutron scattering measurements of the phonon-roton (P-R) and layer modes of liquid 4He confined in MCM-41 under pressure up to 38 bar. The data shows unambiguously that the P-R mode exists at low temperature only. As temperature is increased, there is a gradual transfer of intensity from the P-R mode to the normal liquid response, which lies at a lower energy at higher pressure. The transfer takes place with no observable mode broadening. The loss of P-R modes is identified with the loss of Bose-Einstein condensation (BEC). The mode giving rise to the specific heat, cV, of liquid 4He in porous media ( e.g., gelsil) at higher temperature is the layer mode since the energy of the mode extracted from cV and the layer mode energy are the same.
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