Bose-Einstein condensation in a stiff TOP trap with adjustable geometry

We report on the realization of a stiff magnetic trap with independently ad justable trap frequencies, omega (z) and omega (r), in the axial and radial directions, respectively. This has been achieved by applying an axial modu lation to a time-averaged orbiting potential (TOP) trap. The frequency rati o of the trap, omega (z)/omega (r), can be decreased continuously from the original TOP trap value of 2.83 down to 1.6. We have transferred a Bose-Ein stein condensate (BEC) into this trap and obtained very good agreement betw een its observed anisotropic expansion and the hydrodynamic predictions. Ou r method can be extended to obtain a spherical trapping potential, which ha s a geometry of particular theoretical interest.