Kinetics of Collisions Involving Laser Cooled Atoms in an Ultra-High Vacuum Environment

摘要

Collision kinetics of laser-cooled cesium (Cs) atoms is investigated in an ultra high vacuum (UHV) environment of a magneto-optical trap (MOT). The process of capture and loss of atoms into and out of the MOT are studied by following the time-dependent fluorescence emanating from the laser cooled atoms when the cooling laser beam is modulated to generate bright and dark periods of unequal intervals. The kinetics of the atom capture is analysed in terms of the linear and quadratic trap loss rates, which are governed respectively by the densities of the background gas and the cold atoms. The linear trap loss is related to the number of background atoms, thereby giving an independent measurement of vacuum in the MOT chamber.