Key
Questions We Want to Answer:
Boundaries
confine a material. For example, the shoreline acts as a
boundary separating the ocean and land. Of course, a child
digging the sand in Malibu does not affect the properties
of seawater in the Central Pacific. However, if the confinement
of a system is reduced in size it is possible to view unusual
interactions between the atoms. The Boundary Effects on
the Superfluid Transition (BEST) experiment studies molecular-level
boundary issues using liquid helium during a phase transition
between fluid and superfluid states. Helium is used for
this experiment because of its high purity in liquid form
and the long history of data describing its superfluid transition
in great detail. BEST adds dynamic boundary effects data
to that understanding.
What We Hope to Find Out:
By studying the dynamic behavior of a material when confined
in different geometries, BEST will advance knowledge of
the fundamental nature of materials when limited to only
one or two dimensions. Because BEST conducts measurements
at a phase transition, it provides information about a much
broader range of phase transitions in other materials, which
helps us understand on a fundamental level how molecules
act together rather than individually.
How We'll Conduct Our Experiment:
The
experiment is constructed with three parallel sample cells
mounted inside a thermally shielding can the size of a coffee
can. The one-dimensional and two-dimensional cell interiors
are divided respectively into cylindrical and pancake-shaped
channels. Simultaneous measurement on all three cells provides
several boundary types for comparison. While heating one
end of the sample, high-resolution thermometers are used
to measure thermal resistance to the heat flow. With various
sizes of confinement channels and a broad pressure range,
BEST provides extensive data for study.
|
