“Dark-spot” atomic-beam slowing for on-axis loading of traps

We have performed continuous slowing of an atomic beam to load a magneto-optical trap (MOT) on axis. To avoid the undesirable effects of the strong slowing laser on the performance of the MOT, a dark spot in the center of the slowing laser beam is used. We varied the spot size and the slowing-laser frequency and intensity to optimize the number of trapped atoms. Our ``dark-spot'' slowing increased the number of trapped atoms by a factor of 30, allowing us to trap ~10⁹ atoms in the MOT.