Intensity and detuning dependence of fine structure changing collisions in a 85Rb magneto-optical trap

This paper reports on an experimental investigation of fine structure changing collisions between cold and trapped 85Rb atoms. Our previous work [Eur. Phys. J. D 7, 317 (1999)] reported on our assessment of the contribution of FSC to the total trap loss using photoionization by a cw laser to detect the atomic fragments in the 5P1/2 state originating from these collisions. The Doppler effect plays an important role in the detection scheme and had a limiting effect on our previous experiment. To overcome this problem, we have used a pulsed laser in this work. The signal/noise ratio was improved, allowing us to measure the intensity and frequency dependence of the loss rate due to FSC. A comparison of our results with the semiclassic Gallagher-Pritchard model revealed some disagreements, for which we propose several arguments to attempt to explain these discrepancies. We believe that these results should stimulate theoretical work on this field. (orig.)