Theoretical study of the optimal conditions for the measurement of the differential cross section of the double ionization of helium by fast electrons

The optimal values of the scattering and the ejection angles and energies are studied in the case of the double ionization of the helium atom by fast-electron impact (5 keV) using a recently developed procedure based on the first Born approximation. This calculation includes several correlated initial-bound-state wave functions and the correlated-double-continuum wave function satisfying the exact asymptotic boundary conditions. Besides its interest for (e-3e) measurements which are in preparation in Orsay, and its utility for supplying immediate results needed for the verification of the different hypotheses of the ionization mechanisms, this work collects information which is potentially important for future calculations of the total cross section for the double ionization of helium.