PhononRoton Excitations of Liquid Helium at Negative Pressures Henry Glyde, University of Delaware,

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Phonon-Roton Excitations of Liquid Helium at
Negative PressuresHenry Glyde, University of
Delaware, Oscar Vilches, University of
Washington,John Larese, University of Tennessee
Focused Research Group, Neutron Scattering
DMR-0115663
We have observed the fundamental phonon-roton
excitations of superfluid 4He held at negative
pressures using neutrons. By stretching liquid
4He between the walls of porous media, we have
reached equilibrium negative pressures to 5
bar. Liquids at negative pressures are of great
interest to reveal liquid binding, explore the
liquid/gas transition and to study cavitation
(bubble formation) and neutron scattering is
now a new tool in their study. Phys. Rev. Lett.
(in press) (2004)
Phonon-Roton Dispersion Curve
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Phonon-Roton Excitations of Liquid Helium at
Negative Pressures Henry Glyde, University of
Delaware, Oscar Vilches, University of
Washington, John Larese, University of Tennessee
Focused Research Group, Neutron Scattering
DMR-0115663

The FRG currently has two post doctoral
associates, one stationed at the Institut Laue
Langevin, Grenoble and the other at the ISIS
neutron Facility, UK, and eleven graduate
students. Educational goals are to train young
scientists in neutron scattering in preparation
for the Spallation Neutron Source (SNS) coming on
line at Oak Ridge National laboratory and to
provide an international research experience for
graduate students. Former post docs, Richard
Azuah, Olivier Plantevin and Francesco Albergamo
(opposite) are now at NIST, Gaithersburg and
ESRF, Grenoble and continue to collaborate with
the FRG.