Spatial diffusion of atoms cooled in a speckle field

Spatial diffusion of atoms in a disordered molasses created by a specific f ield is studied both numerically and experimentally. It is shown that the r atio T/D-s (kinetic temperature divided hs spatial diffusion coefficient) c an he expressed as a simple function of the light-shift, the frequency detu ning from resonance and che speckle size. We find that the transition from the jumping to the oscillating regime of laser cooling is clearly reflected in the behaviour of this ratio.