Two-electron capture by He2+, Li3+, and B5+ in the independent-event model

We apply a single-channel distorted-wave approximation in conjunction with the independent-event model to calculate the double-capture cross sections by He2+, Li3+, and B5+ from neutral He. The capture probabilities of the two electrons in two successive independent events are calculated by a single-channel distorted-wave approximation with realistic screening charge parameters. Our T matrix has been evaluated analytically and therefore the present method is much simpler than other available rigorous calculations. Our results are compared with the measurements and other calculations. It is found that the present method gives fairly good agreement with the measurements. copyright 1996 The American Physical Society