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

This paper reports on an experimental investigation of this structure chang ing collisions between cold and trapped Rb-85 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 lancer to detec t the atomic fragments in the 5P(1/2) state originating from these collisio ns. The Doppler effect plays all 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 impr oved, allowing us: to measure the intensity and frequency dependent of the loss rate due to FSC. A comparison of our results with the semiclassic Gall agher-Pritchard model revealed some disagreements, for which we propose sev eral arguments to attempt to explain these discrepancies. We believe that t hese results should stimulate theoretical work on this field.