DIRECT MEASUREMENT OF FINE STRUCTURE CHANGING COLLISION IN COLD Rb: INTENSITY DEPENDENCE M. Mancini, K. M. F. Magalh\~aes, A.L. Oliveira and L.G. Marcassa Instituto de F\'{\i}sica de S\~ao Carlos Universidade de S\~ao Paulo Cx. Postal 369 - S\~ao Carlos -SP - Brasil 13.560 - 970 In this work we present the intensity dependence of Fine Structure Changing Collision in a sample of cold trapped Rb. The atoms in P$_{1/2}$, after the collision, are photoionized by a pulsed dye laser using the transition 5P$_{1/2}\Rightarrow $ 8S$_{1/2}$.