Third sound resonance studies of /sup 3/He-/sup 4/He mixture films

Thesis/Dissertation · Tue Jan 01 04:00:00 EST 1985

OSTI ID:5572248

Heinrichs, R M

Third sound velocity and dissipation measurements were performed on /sup 3/He-/sup 4/He mixture films of 3.6 and 5.3 layers /sup 4/He and up to 3 added layers /sup 3/He in the temperature range 0.05-0.3 K using third sound resonance techniques. The /sup 3/He concentration dependence of the velocity was in excellent agreement with a simple layered film model down to the lowest concentrations studied. At the higher /sup 3/He concentrations, the velocity began to deviate from the model, rising above it. The concentration dependence of the dissipation showed some unique structure with a maximum at 0.3-0.5 layers added /sup 3/He for both /sup 4/He coverages. The third sound velocity in the low concentration mixture films had very little temperature dependence in the range studied. The dissipation, however, had some definite temperature dependent structure that evolved with concentration. This evolution was most pronounced at concentrations near the dissipation maximum and eventually became exponential at the higher coverages. Fitting these exponentials produced estimates of the difference in binding energy for the /sup 3/He states in and on the film. In this higher /sup 3/He concentration regime, a temperature dependence of the velocity was observed that began as a small peak at about 0.15 K and eventually became a step at the highest concentrations studied. The exponential nature of the dissipation became clouded when the velocity evolved into this last behavior.

• Research Organization: Massachusetts Univ., Amherst (USA)
• OSTI ID: 5572248
• Country of Publication: United States
• Language: English

Related Subjects

640450* -- Fluid Physics-- Superfluidity
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
DISPERSIONS
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
FILMS
HELIUM 3
HELIUM 4
HELIUM ISOTOPES
ISOTOPES
LIGHT NUCLEI
MIXTURES
NUCLEI
QUANTITY RATIO
RESONANCE
STABLE ISOTOPES
TEMPERATURE DEPENDENCE
THIRD SOUND
ULTRALOW TEMPERATURE
VELOCITY