Measurement of the Low-Energy Rb+–Rb Total Collision Rate in an Ion-Neutral Hybrid Trap**Supported by the National Natural Science Foundation of China under Grant Nos 11604334, 61227807 and 61575108, and the Tsinghua Initiative Scientific Research Program under Grant No 2013THZ02-3, and the Beijing Natural Science Foundation under Grant No 1164016.

Abstract

An ion–neutral hybrid trap is built to study low-energy ion–atom collisions. The ion–neutral hybrid trap is combined with two spatially concentric traps: a linear Paul trap for the ionic species and a magneto-optical trap (MOT) for the neutral species. The total ion–atom collision rate coefficient between87Rb atoms and optically dark 87Rb+ ions is measured by monitoring the reduction of the steady-state MOT atoms by sequentially introducing various mechanisms, namely photoionization and ion–atom collisions. In contrast to other experiments, a concise experimental procedure is devised to obtain the loss rates of the MOT atoms due to photoionization and ion–atom collisions in one experimental cycle, and then the collision rate of cold 87Rb atoms with 87Rb+ ions is deduced to m3/s with K measured by the time of flight of the ion signal. The measurements show good agreement with the collision rate derived from the Langevin model.