Energy partitioning between ejected electrons following electron impact valence double ionization of argon

The electron impact outer-shell double ionization of argon has been investigated at 5.5 keV incident energy. (e, (3-1)e) experiments in which two of the three electrons present in the continuum are detected in coincidence have been performed, yielding fourfold differential cross sections. The energy distribution of the two ejected electrons is reported. The observed non-symmetric shape may be attributed to the different angular distribution of the fast and slow ejected electrons.