Distorted wave calculations for the spin asymmetry in impact ionisation of polarised atoms by polarised electrons

We discuss impact ionisation of polarised atoms (Li, Na, K and metastable excited He) by polarised electrons. The consequences of the 'maximum interference approximation' in theoretical 'distorted wave' calculations for the total cross sections and the spin asymmetry are investigated. Numerical results obtained with the distorted wave born approximation (DWBA) method are compared with recent experimental data. The agreement between theory and experiment is only marginal. This indicates that more sophisticated methods are needed to enable correct theoretical predictions of the spin dependent ionisation asymmetry. (author)