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 kia between87 Rb atoms and optically dark 87 Rb+ 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 kia of cold 87 Rb atoms with 87 Rb+ ions is deduced to 0.94(±0.24) × 10-13 m3/s with Ti =3770(±100) 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.