Suppression of Atomic Radiative Collisions by Tuning the Ground State Scattering Length

Abstract

We investigate the radiative collision rate in an ultracold, optically trapped cesium gas near a magnetically tunable Feshbach resonance. The radiative trap loss is suppressed by a factor of up to 15 when the node of the ground state pair correlation function is tuned to the Condon point. This constitutes a direct measurement of both the sign and the magnitude of the $s$-wave scattering length. In addition, we observe several narrow, superimposed loss resonances. Their widths are determined by the gas temperature, and their positions are independent of external parameters to within 5 mG.