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$_{1/2}$.