Accession Number : AD0680670

Title :   COLLECTIVE OSCILLATIONS IN He3-He4 MIXTURES.

Descriptive Note : Research Communication no. 69,

Corporate Author : DOUGLAS AIRCRAFT CO INC HUNTINGTON BEACH CALIF ADVANCED RESEARCH LABS

Personal Author(s) : Etters,Richard D. ; Raich,John C.

Report Date : AUG 1968

Pagination or Media Count : 33

Abstract : The existence of 'collisionless' phonons in He(3)-He(4) mixtures is predicted on the basis of a self-consistent field calculation. The phonon velocity is calculated for all temperatures over the region 0 < 0 < 1.5K and for all molar concentrations of He(3). The velocity is found to increase monotonically with increasing temperature for all molar concentrations. Significantly, the behavior of these excitations is not overtly sensitive to the state of the superfluid. It is argued that the phonon excitation of pure He(4) and the zero-sound mode of pure He(3) belong to the same branch and evolve continuously into one another as the fractional concentration of He(3) in the mixture changes from zero to unity. The differential inelastic X-ray scattering cross section is also calculated for the mixture. (Author)

Descriptors :   (*HELIUM, *SUPERFLUIDITY), ISOTOPES, MIXTURES, LIQUEFIED GASES, PHONONS, X RAYS, SOUND

Subject Categories : Thermodynamics

Distribution Statement : APPROVED FOR PUBLIC RELEASE