Coincident detection of electrons ejected at large angles and target recoil ions produced in multiply ionizing collisions for the 1-MeV/u Oq++Ar collision system.

Abstract

The angular distributions of energetic electrons ejected at angles between 45[degree] and 135[degree] with respect to the incident-beam direction have been measured in coincidence with the charge states of the target recoil ions produced in multiply ionizing collisions for the 1-MeV/u O[sup [ital q]+] ([ital q]=4,7)+Ar collision systems. These measurements have been made for [similar to]179-, [similar to]345-, and [similar to]505-eV electrons. Additionally, the energy distributions of electrons ejected into specific angular regions have been measured. Ar [ital LMM] satellite Auger electrons appear as a peak in the energy spectrum of electrons ejected at all large angles. The center of this peak is found at an electron energy of [similar to]179 eV. Electrons with [similar to]179 eV energy, ejected at large angles, are preferentially produced in coincidence with recoil ions of charge state 4+. Electrons with [similar to]345 eV energy and [similar to]505 eV energy ejected at large angles are preferentially produced in coincidence with recoil ions of charge state 3+. The angular distributions for these electrons are strongly peaked in the forward direction; essentially no electrons are observed at angles larger than 90[degree]. These results are consistent with the dominant production mechanism for energetic electrons ejected at large anglesmore » being a binary-encounter process. Differential cross sections have been calculated from these angular distributions. They are on the order of 10[sup [minus]21] cm[sup 2]/(eV sr).« less