München 2004 – wissenschaftliches Programm

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SYDV: Multifragmentimaging-Dynamik in Vielteilchensystemen

SYDV 1: Sitzung 1

SYDV 1.1: Hauptvortrag

Montag, 22. März 2004, 14:00–14:30, HS 133

Three-Dimensional Imaging of Ionization Processes — •Michael Schulz — University of Missouri Rolla, Missouri, USA

Atomic collisions represent particularly suitable testground to study the few-body problem, which is still one of the fundamentally important, unsolved problems in Physics. For ionization of He by charged particle impact kinematically complete experiments have been performed since the pioneering work of Ehrhardt et al. [1]. It was thought that a profound knowledge of the basic features observed in the fully differential cross sections had emerged, at least for single ionization at large collision energies. These conclusions are, however, almost exclusively based on studies which were performed for restricted electron-emission geometries. Here, we present complete measured and calculated three-dimensional images of the fully differential electron emission patterns for single ionization by ion impact [2]. Nearly fully differential cross sections were obtained for double ionization. In the data we observe unexpected features which so far were not predicted by any published theoretical model. We propose a higher-order ionization mechanism involving the projectile * target nucleus interaction to explain these features. Work supported by NSF and DFG.

[1] H. Ehrhardt et al., Phys. Rev. Lett. 22, 89 (1969) [2] M. Schulz et al., Nature 422, 48 (2003)