184 research outputs found
Volume element structure and roton-maxon-phonon excitations in superfluid helium beyond the Gross-Pitaevskii approximation
We propose a theory which deals with the structure and interactions of volume
elements in liquid helium II. The approach consists of two nested models linked
via parametric space. The short-wavelength part describes the interior
structure of the fluid element using a non-perturbative approach based on the
logarithmic wave equation; it suggests the Gaussian-like behaviour of the
element's interior density and interparticle interaction potential. The
long-wavelength part is the quantum many-body theory of such elements which
deals with their dynamics and interactions. Our approach leads to a unified
description of the phonon, maxon and roton excitations, and has noteworthy
agreement with experiment: with one essential parameter to fit we reproduce at
high accuracy not only the roton minimum but also the neighboring local maximum
as well as the sound velocity and structure factor.Comment: 9 pages, 6 figure
Measurements on the absorption of sound in O2-gas and in CO2 gas containing small quantities of H2O, D2O and Ne. Relaxation times for the vibrational energy
Bestimmung der inneren reibung von schwerem und leichtem methan zwischen 322° K und 90° K
Adsorption isotherms and heats of adsorption of helium gas on charcoal between 20°K and 6°K - new desorption experiments -
Measurements on the adsorption of different gases on copper at liquid oxygen and liquid hydrogen temperatures and at low pressures
Measurements on the adsorption of helium gas on active charcoal between 4.22 °K and 1.78 °K
Mesures sur l'absorption et la vitesse de propagation du son dans l'hydrogène léger et l'hydrogène lourd entre 300°K et 60°K
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