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Second Born triple differential cross sections for the coplanar asymmetric ionisation of He(21S) and He(23S) by fast electrons and positrons

par Vučić, Svetlana;Potvliege, Robert ;Joachain, Charles
Référence Journal of Physics. B, Atomic Molecular and Optical Physics, 22, 21, page (3519-3527), 014
Publication Publié, 1989

Article révisé par les pairs

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Résumé :

Triple differential cross sections for the single ionisation of helium from the metastable states 21S and 23S by fast electrons and positrons are calculated in the second Born approximation for the case of an asymmetric coplanar geometry. Results are presented at an incident projectile energy of 250 eV and are qualitatively similar to those found for ionisation from the metastable 2s state of atomic hydrogen. The second-order effects are more important for incident positrons than for incident electrons. For both electron and positron impact, the second-order effects are more important for ionisation from the 21S state than from the 23S state, a feature which is related to the larger polarisability of the 21S state.