Atomic motion in a time-dependent standing wave of light provides an almost ideal experimental
system for the study of quantum chaos, due to the nonlinearity of the potential combined with negligible dissipation.
In our first experiments with sodium atoms we observed dynamical localization, a quantum suppression
of chaotic diffusion. To go beyond this work we have constructed an experiment with cold cesium atoms, and
report our first results from this system. The larger mass and longer wavelength push out the momentum boundary
in phase space that arises from the nonzero duration of the pulses. This feature should enable the study of
effects leading to delocalization.