Transitions between stable spatial distributions of atoms in a magneto-optical trap

We report on controlled changes between stable spatial distributions of ato ms in a magneto-optical trap. As the misalignment between the trapping lase r beams is increased, the cloud of atoms evolves from a spherical distribut ion to a ring with a central core and finally to a ring without a core. The changes are explained according to previous work done by our group [Opt. C ommun., 15, 85 (1995), Phys. Rev. A, 48, 3771 (1993)] where we theoreticall y predicted such transitions.