Ultrasonic measurements as a probe of {sup 3}He-{sup 4}He phase separation in aerogels

Journal Article · Wed Nov 01 04:00:00 EST 1995 · Journal of Low Temperature Physics

DOI:https://doi.org/10.1007/BF00753326· OSTI ID:183396

Paetkau, M; Beamish, J ^[1]

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1. Univ. of Alberta, Edmonton (Canada)

We have used ultrasonic velocity and attenuation measurements to study the phase separation of {sup 3}He/{sup 4}He mixtures confined in a silica aerogel with a porosity of 87%. We used both shear and longitudinal sound and varied the frequency between 4 and 20 MHz. The superfluid transition is accompanied by a velocity increase due to decoupling and by a critical attenuation peak which increases with frequency. At the phase separation there are changes in the velocity and attenuation, and hysteresis on thermal cycling. We show some recent results and discuss how they relate to the phase diagram inferred from torsional oscillator and heat capacity measurements on helium mixtures in aerogels.

• Sponsoring Organization: USDOE
• OSTI ID: 183396
• Report Number(s): CONF-950676--
• Journal Information: Journal of Low Temperature Physics, Journal Name: Journal of Low Temperature Physics Journal Issue: 3-4 Vol. 101; ISSN JLTPAC; ISSN 0022-2291
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
66 PHYSICS
HELIUM 3
HELIUM 4
HYSTERESIS
MIXTURES
PHASE DIAGRAMS
PHASE TRANSFORMATIONS
SILICA GEL
SPECIFIC HEAT
SUPERFLUIDITY
TEMPERATURE DEPENDENCE
ULTRASONIC TESTING