Observation of radiation trapping in a dense Cs magneto-optical trap

We present an experimental and theoretical investigation of the resonant radiation trapping phenomenon in a magnetooptical trap (MOT) for cesium atoms. We have resonantly excited the 6(2)S(1/2)(F = 4)-6(2)P(3/2)(F' = 5) transition with a probe laser and measured directly its effective radiative lifetime. We compare our experimental data with a model based on an approximate solution of the Holstein equation and with a Monte Carlo simulation of the process. The inadequacy of the standard theory for thermal atomic samples in reproducing the data is pointed out. (C) 1998 Elsevier Science B.V.