Measuring the capture velocity of atoms in a magneto-optical trap as a function of laser intensity

Using the dark-spot Zeeman-tuned slowing technique, we have measured the capture velocity of a magnetooptical trap as a function of the trap laser intensity. The values obtained are in reasonable agreement with calculations based on a simple model. Nevertheless, the dependence of capture velocity in the low-intensity regime seems to be slightly different from the predictions. The measurement of this type of trap parameter is of interest in the analysis of exoergic cold collisions, where the knowledge of such values is important for the interpretation of experimental results.