J. Phys. IV France
Volume 09, Numéro PR6, June 1999
International Conference on Coincidence Spectroscopy
Page(s) Pr6-89 - Pr6-92
International Conference on Coincidence Spectroscopy

J. Phys. IV France 09 (1999) Pr6-89-Pr6-92

DOI: 10.1051/jp4:1999620

Double ionization of helium by fast electron impact

A. Dorn1, R. Moshammer1, C.D. Schröter1, T.J.M. Zouros2, W. Schmitt3, H. Kollmus1, R. Mann3 and J. Ullrich1

1  Universität Freiburg, Hermann-Herder-Str. 3, 79104 Freiburg, Germany
2  Department of Physics, University of Crete, 71003 Heraklion, Greece
3  Gesellschaft für Schwerionenforschung, 64220 Darmstadt, Germany

We report on a kinematically complete investigation of He double ionization by 3 keV electron impact. A new experimental approach for experiments on electron impact ionization is applied : in a multi-electron recoil-ion coincidence the momentum vectors of the recoiling ion and of two slowly ejected electrons (Eb,c < 20 eV) are determined. The momentum of the fast scattered electron follows from momentum conservation. By examining the double ionization process as a function of the momentum transferred to the target by the scattered projectile different kinematical regimes are separated. For small values of the momentum transfer the angular correlation and the energy partitioning of the slowly ejected electrons exhibit the characteristics of double photoionization. For Bethe ridge kinematics signatures of the TS 1 ionization mechanism are observed.

© EDP Sciences 1999