A STATIC MEAN-FIELD MODEL FOR INCLUSIVE CROSS-SECTIONS INVOLVING COLLISION OF IONS EACH BEARING AN ELECTRON

We introduce a simple static mean field model for calculations of cros s sections involving the collision of ions each bearing an electron. T he model is designed for calculating a specific excitation cross secti on of a target for which no information is available as to the final s tate of the projectile. We believe the approach will be most accurate when the target nuclear charge is large compared to the charge of the projectile nucleus. The model is perhaps counterintuitive: the prescri ption is to calculate the mean field screening produced by averaging t he projectile electron over its initial state density and then to set to zero the matrix elements of the screening potential that connect th e initial and final states of the target. An application to the 1s-2s excitation of He+ by H is made; the model largely reproduces the exper iments of Shah and Gilbody. We also present results for excitation of Li2+ by H.