Precision velocimetry in a thermal atomic beam by stimulated optical Compton scattering

We have demonstrated that Raman transitions between adjacent momentum states of ground-state atoms can be used for velocimetry. We report measurements of the transverse velocity distribution of atoms in a beam with a thermal longitudinal velocity. The atomic density was 100 times lower than atoms released from a magneto-optical trap, and the resolution was a few recoils, under conditions where the usual geometric measurement would have been 100 times worse.