Measurement of the low-energy Na+-Na total collision rate in an ion-neutral hybrid trap

We present measurements of the total elastic and resonant charge-exchange ion-atom collision rate coefficient kia of cold sodium (Na) with optically dark low-energy Na+ ions in a hybrid ion-neutral trap. To determine kia, we measured the trap loading and loss rates from both a Na magneto-optical trap (MOT) and a linear radio-frequency quadrupole Paul trap. We found the total rate coefficient to be 7.4 +/- 1.9 x 10(-8) cm(3)/s for the type-I Na MOT immersed within an approximate to 140-K ion cloud and 1.10 +/- 0.25 x 10(-7) cm(3)/s for the type-II Na MOT within an approximate to 1070-K ion cloud. Our measurements show excellent agreement with previously reported theoretical fully quantal 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.