Trap-depth measurements using ultracold collisions

We measure the depth of an optical atom trap using repulsive trap-loss collisions. These collisions involve excitation by a laser tuned to a frequency above the atomic resonance. Simple conservation of energy considerations give direct quantitative measurements of the trap depth. Further analysis allows measurement of the escape probability as a function of energy. We apply the methods to Rb traps, and use the results to form conclusions about ground-state hyperfine-changing collisions.