Rydberg tagging time-of-flight imaging to study ultracold collisions*

We have further developed Rydberg tagging time-of-flight and imaging techniques so that they can effectively be used to study ultracold collisions. We have realized a velocity resolution of $\sim2.5$ cm/s with our apparatus. This resolution enables Rydberg tagging time-of-flight and imaging spectroscopy to determine the exit channel of an ultracold collision. Results and prospects for applying these methods to measure differential cross-sections for Rydberg atom collisions, photoassociative collisions, and three-body recombination will be presented.