Production of ultracold NH molecules by sympathetic cooling with Mg.

We show that sympathetic cooling of NH molecules by Mg atoms has a good prospect of success. We carry out calculations on M-changing collisions of NH (3Sigma-) molecules in magnetically trappable states with Mg, using a recently calculated potential energy surface. We show that elastic collision rates are much faster than inelastic rates for a wide range of fields at temperatures up to 10 mK and that the ratio increases for lower temperatures and magnetic fields.