Measurement of the density of dilute solutions of /sup 3/He in /sup 4/He

Thesis/Dissertation · Wed Jan 01 04:00:00 EST 1986

OSTI ID:6772000

Nagurney, L S

The density of dilute solutions of /sup 3/He in /sup 4/He was measured using a superconducting resonant cavity for temperatures from .2 to .5 K and He/sub 3/ concentrations from 1.21 x 10/sup -4/ to 2.1 x 10/sup -3/. For these dilute solutions the thermal expansion due to the He/sub 3/ quasi particles is independent of the thermal expansion due to the /sup 4/He. The /sup 3/He quasi particles may be described as a Fermi gas with effective mass 2.34 times the bare mass. The experimental results were fit to three different excitation spectra, a free particle one, a free particle with a weak term quartic in the momenta, and one quadratic in the momenta with an effective mass that increases linearly with momenta. The normalized logarithmic pressure derivative of the effective mass was computed and found in agreement with one derived from second sound measurements at various pressures. The logarithmic pressure derivative of the coefficients of the nonparabolic terms were calculated. The signs of these derivatives indicate that at higher pressures the dispersion curve of the dilute solution becomes closer to a pure quadratic. The possible expansion due to the existence of a pure quadratic. The possible expansion due to the existence of a /sup 3/He Roton was calculated and found to have different temperature dependence but smaller magnitude than the phonon/quasi particle indicating its detection in this experiment highly unlikely.

• Research Organization: Brown Univ., Providence, RI (USA)
• OSTI ID: 6772000
• Country of Publication: United States
• Language: English

Related Subjects

640450* -- Fluid Physics-- Superfluidity
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
CAVITY RESONATORS
DENSITY
DISPERSIONS
EFFECTIVE MASS
ELECTRONIC EQUIPMENT
EQUIPMENT
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
FERMI GAS
FLUIDS
GASES
HELIUM 3
HELIUM 4
HELIUM ISOTOPES
ISOTOPES
LIGHT NUCLEI
MASS
MEASURING METHODS
MIXTURES
NUCLEI
PHYSICAL PROPERTIES
RESONATORS
STABLE ISOTOPES