Suppression of trap loss collisions at low temperature

We report on measurements of the temperature dependence of trap loss collisions of laser-cooled rubidium atoms. A significant suppression of the rate of collisions between ground- and excited-state atoms is observed for temperatures below [similar to]70[mu]K. In such inelastic collisions, the atomic excitation takes place at long range and must survive against spontaneous decay to short range. Our results are consistent with recent predictions for the low temperature suppression of these collisions due to reduced survival of atomic excitation at low collision velocities.