We present measurements of the total elastic and resonant charge-exchange ion-atom collision rate coefficient $k_\mathrm{ ia}$ of cold sodium (\ce{ Na}) with optically-dark low energy \ce{ Na+} ions in a hybrid ion-neutral trap. To determine $k_\mathrm{ ia}$, we measured the trap loading and loss from both a \ce{ Na} magneto-optical trap (MOT) and a linear radio frequency quadrupole Paul trap. We found the total rate coefficient to be $7.4 \pm 1.9 \times 10^{ -8}$ cm$^3$/s for the type I \ce{ Na} MOT immersed within an $\approx 140$ K ion cloud and $1.10 \pm 0.25 \times 10^{ -7}$ cm$^3$/s for the type II \ce{ Na} MOT within an $\approx 1070$ K ion cloud. Our measurements show excellent agreement with previously reported theoretical fully quantal \textit{ ab initio} calculations. In the process of determining the total rate coefficient, we demonstrate that a MOT can be used to probe an optically dark ion cloud's spatial distribution within a hybrid trap.
Categories: physics.atom-ph