= Abel-Anderson-Wheatley zero-sound experiment
{c}
In 1966, <William Russell Abel>, <Ansel Cochran Anderson> and <John Charles Wheatley> sent <acoustic waves> through bulk liquid <helium-3> at $0.32\ \mathrm{atm}$ and frequencies $15.4$ and $45.5\ \mathrm{MHz}$. A <quartz> delay line and receiving <acoustic transducer> bounded a $0.138\ \mathrm{mm}$ liquid gap; shielding reduced electrical pickup. Powdered <cerium magnesium nitrate> provided magnetic thermometry during a slow warm-up. Pulse amplitudes measured <acoustic attenuation>; <phase difference> comparison measured velocity. Calibration pulses checked gain; early received cycles avoided multiple reflections. On cooling through a maximum, <acoustic attenuation> changed from $\alpha\propto\omega^2/T^{*2}$ to $\alpha\propto T^{*2}$ with a velocity shift supporting <zero sound>; $T^*$ is their magnetic <temperature> scale. Weak <acoustic attenuation> was harder to resolve.<Propagation of Zero Sound in Liquid He3 at Low Temperatures by William Russell Abel and others>[pp.74–75, Fig.1 and readout/control paragraphs]{ref}
This 1966 test followed <Lev Landau>'s 1962 <Nobel Prize in Physics>.<The Nobel Prize in Physics 1962 by Nobel Prize Outreach>[1962 award to Landau for condensed-matter theory]{ref}
The experiment concerned normal liquid <helium-3>, distinct from the later discovery of <superfluid> <helium-3>.<John C. Wheatley by Robert E. Ecke and others>[pp.3–4, normal-liquid sound and later superfluid work]{ref} Landau's original papers are theoretical calculations, not reports of an apparatus.
Back to article page
