A dual-stage laser ablation source for cold atoms?

A recent publication reports a low velocity, low divergence atomic beam generated by laser ablation [RSI 76, 113302 (2005)]. The reported velocities of 40 m/s and divergences of 20 mrad seem physically impossible for ablation sources. They were determined indirectly by measuring the index of refraction using a far-off-resonance laser. We report our efforts to reproduce this experiment and to measure the atomic density and velocity directly using laser induced fluorescence in an ablated calcium beam.