Anisotropic magneto-optical trapping of atoms: capture efficiency and induced drift velocities

An anisotropic magneto-optical trap is studied as the potential source of a continuous beam of laser-cooled atoms. Capture efficiency and cloud temperature are measured experimentally and found to be lower than in an isotropic situation with the same cooling parameters. Intensity imbalance and static magnetic field are investigated as possible extraction mechanisms. While only small drift velocities are induced by means of intensity imbalance, velocities of tens of cm s^-1 are observed with a static magnetic field; the shape of the observed two-peaked velocity distributions is related to the average depth of local light-shift-induced potential wells.