Absolute doubly differential cross sections for electron emission in collisions of 3.5-MeV/u Fe17+ and Fe22+ ions with He and Ar gas targets.

Abstract

Absolute doubly differential cross sections have been measured as a function of electron energy and angle of observation for electron emission in collisions of 3.5-MeV/u ${\mathrm{Fe}}^{17+}$ and ${\mathrm{Fe}}^{22+}$ ions with He and Ar gas targets under single-collision conditions. The measured electron emission cross sections are compared to theoretical and scaled cross sections based on the Born approximation. The results using intermediate-mass ions are discussed with reference to previously reported cross sections from collisions with highly charged lighter- and heavier-ion species at MeV/u projectile energies. The continuum--distorted-wave--eikonal-initial-state approximation shows good agreement with experiments except in the ``binary-encounter peak'' where the interaction between projectile electrons and target electrons could play an important role.