Zobrazeno 1 - 10
of 162
pro vyhledávání: '"A. F. G. Wyatt"'
Publikováno v:
Low Temperature Physics. 44:1062-1065
The angular distribution of the energy density of an anisotropic “phonon sheet” was studied during its propagation in superfluid 4He at pulse duration up to 300 ns. The presence of a flat segment on the angular dependencies of phonon signal is ex
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::5ac37b68f147dff51e671e1de169f2ec
https://doi.org/10.1063/1.5055848
https://doi.org/10.1063/1.5055848
Publikováno v:
Journal of Low Temperature Physics. 159:549-575
We solve the problem of beams of phonons and rotons incident on, and interacting with, solid surfaces. Phonons and rotons are the quasiparticles of superfluid helium and have a unique dispersion curve. The dispersion curve controls the transmission,
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::cbb3311dff5443d9761db614e8073671
https://doi.org/10.1007/s10909-010-0165-8
https://doi.org/10.1007/s10909-010-0165-8
Publikováno v:
Journal of Low Temperature Physics. 157:509-526
We show that a thin film gold heater, on polished sapphire, radiates phonons into liquid helium by both the acoustic and background channels. To analyse the measured angular distributions of phonons, at a pressure of 24 bar, we derive an expression f
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::b60b37f1b3bf277f997c1fce25cdbff7
https://doi.org/10.1007/s10909-009-0011-z
https://doi.org/10.1007/s10909-009-0011-z
Publikováno v:
Low Temperature Physics. 33:767-773
We discuss a number of unusual phenomena discovered recently in anisotropic quasiparticle systems in superfluid He4. These include the creation of high-energy phonons by a pulse of low-energy phonons, the suprathermal distribution of high-energy phon
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::3d553aebaeb44609585a5bef67c5193a
https://doi.org/10.1063/1.2780172
https://doi.org/10.1063/1.2780172
Publikováno v:
Journal of Low Temperature Physics. 148:547-552
In this paper we consider the problem of second sound propagation in a quasiparticle system which has a high level of anisotropy. The main aim of the research is to derive an exact expression for the second sound velocity in such a system, which is v
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::0b5bc6bc7f81035e74d8babe8301d7bd
https://doi.org/10.1007/s10909-007-9479-6
https://doi.org/10.1007/s10909-007-9479-6
Publikováno v:
Low Temperature Physics. 33:387-400
The problem of the creation of high-energy phonons (h-phonons) by a pulse of low-energy phonons (l-phonons) moving from a heater to a detector in superfluid helium is solved. The rate of h-phonon creation is obtained, and it is shown that the h-phono
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::12664a5fa66b2af6553776f56074c9f1
https://doi.org/10.1063/1.2737546
https://doi.org/10.1063/1.2737546
Publikováno v:
Journal of Low Temperature Physics. 145:387-407
We investigate the relaxation of boundless and anisotropic quasiparticle systems, in liquid 4He, with given initial values of momentum and energy densities. The evolution is governed by the dispersion curve which determines the interactions between q
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::cb11e40ca16c247a3512527ec550ef23
https://doi.org/10.1007/s10909-006-9250-4
https://doi.org/10.1007/s10909-006-9250-4
Publikováno v:
Journal of Physics: Condensed Matter. 18:10179-10191
The rate of one phonon decaying into three is calculated in the momentum range where one phonon decaying into two is forbidden in liquid 4He. Exact and useful approximate expressions for the rate are obtained. Its dependence on all parameters, and th
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::5c15ab204498c54b504176ad1c03e5dd
https://doi.org/10.1088/0953-8984/18/45/006
https://doi.org/10.1088/0953-8984/18/45/006
Publikováno v:
Journal of Physics: Condensed Matter. 18:2805-2816
The thermodynamic functions of anisotropic phonon systems in superfluid helium are calculated for all levels of anisotropy. The results show that the thermodynamic functions of strongly anisotropic phonon systems are essentially different from isotro
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::28b99be03be993005eadf4ca6fc71a4b
https://doi.org/10.1088/0953-8984/18/10/006
https://doi.org/10.1088/0953-8984/18/10/006
Publikováno v:
Journal of Physics: Condensed Matter. 17:2859-2871
The longitudinal evolution of a low energy phonon pulse in superfluid helium 4He is analysed theoretically. The phonons are considered to be strongly interacting and are described by the exact local equilibrium distribution function. The theory descr
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::016fd768ae8279fe8a2caa4853ee3a3e
https://doi.org/10.1088/0953-8984/17/19/004
https://doi.org/10.1088/0953-8984/17/19/004