Improved characterization of elastic scattering near a Feshbach resonance in Rb-85 - art. no. 024702

We report extensions and corrections to the measurement of the Feshbach res onance in Rb-85 cold atom collisions reported earlier [J. L. Roberts et al. , Phys. Rev. Lett. 81, 5109 (1998)]. In addition to a better determination of the position of the resonance peak [154.9(4) G] and its width [11.0(4) G ], improvements in our techniques now allow the measurement of the absolute size of the elastic-scattering rate. This provides a measure of the s-wave scattering length as a function of magnetic field near the Feshbach resona nce and constrains the Rb-Rb interaction potential.