The electron loss process at backward observation angles in collision systems He+(2 MeV)-He, Ne, Ar

The electron loss peak was investigated at backward observation angles (95-170') for 2 MeV (0.5 MeV amu -1 ) He + projectiles and three different targets (He, Ne, Ar). The single differential cross section (SDCS), the peak position and the full width at half maximum were determined as functions of the observation angle. The experimental SDCS values show significant target dependence and they are similar to those for elastically scattered electrons with equal velocity. Data calculated in the electron impact approximation show better agreement with the experimental ones than those calculated with the plane-wave (or first) Born approximation.