Experiments with Supersonic Beams as a Source of Cold Atoms

Chapter 1
Introduction
General control of atomic motion is a long standing goal of atomic physics,
which is motivated by a desire for increased precision in spectroscopy, tests of fun-
damental symmetries, studies of entanglement, many-body physics, and even solid
state physics. The ultimate goal is the ability to cool and trap any atom or molecule
to quantum degeneracy. Laser cooling, for example, has been extremely successful,
but has been limited to a few atomic species. While degenerate gases of alkali atoms
has provided a rich field of study, the lack of generality have limited studies of other
atoms, which may be hiding interesting physics.
The starting point for many atomic physics experiments is an atomic beam. A
simple effusive beam can be created from almost any species, simply by allowing gas to
escape from an aperture into vacuum. This may be done with a gas reservoir, an oven,
or any number of other configurations, making the effusive beam an extremely general
technique. While they are simple to create, effusive beams do have several drawbacks.
Most notably, the temperature of the atoms in an effusive beam is the same as the
temperature in the gas reservoir. This disadvantage is particularly problematic when
an experiment requires cold atoms for greater precision. Effusive beams also generally
have somewhat low brightness, which can limit the number of atoms available for an
experiment.
To address these problems, there are two approaches one can take. One so-
lution is to start with a hot beam of atoms and to subsequently cool it, thereby
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