Neutron reflection from the surface of normal and superfluid 4He

T. R. Charlton; R. M. Dalgliesh; A. Ganshin; O. Kirichek; S. Langridge; P. V. E. McClintock

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arXiv · 0712.0745

Neutron reflection from the surface of normal and superfluid 4He

T. R. Charlton·R. M. Dalgliesh·A. Ganshin·O. Kirichek·S. Langridge·P. V. E. McClintock

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Abstract

The reflection of neutrons from a helium surface has been observed for the first time. The 4He surface is smoother in the superfluid state at 1.54 K than in the case of the normal liquid at 2.3 K. In the superfluid state we also observe a surface layer ~200 Angstroms thick which has a subtly different neutron scattering cross-section, which may be explained by an enhanced Bose-Einstein condensate fraction close to the helium surface.

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T. R. Charlton, R. M. Dalgliesh, A. Ganshin, O. Kirichek, S. Langridge, P. V. E. McClintock. 2007-12-05. Neutron reflection from the surface of normal and superfluid 4He. https://arxiv.org/abs/0712.0745

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