Double Ionization of Helium by Fast Electron Impact

A central issue in modem atomic physics is the understanding of the role of static and dynamic electron-electron correlation in multi-electron transitions. In this respect the investigation of double ionization of helium induced in collisions with projectiles is fundamental since it presents the simplest particle impact induced three body break-up and it is the first step in order to understand multiple ionization processes. Experiments aim to obtain fully differential cross sections since they provide the most stringent tests for theory and to give an understanding of the mechanisms involved for a large range of incident energies and of the final state momentum space. For double ionization of helium by electron impact very few experimental results are available and besides the present study only one kinematically complete experiment using conventional electron spectrometry was performed by (1998).