Differential ionization of Ar by positron and electron impact

Abstract

Coincidences between recoil ions–ejected electrons, and recoil ions–scattered projectiles were used to study the kinematics of electron and positron impact ionization. Differential studies, recently performed at the University of Missouri-Rolla, for 500eV electron and positron impact on Ar are presented. The positron and electron beams are produced by means of a 22Na source and an electron gun respectively. The target is a simple gas jet. An electrostatic energy analyzer and a position sensitive detector measure the post-collision projectile energies and scattering angles. A channeltron counts recoil ions which are extracted by means of an electric field. In the opposite direction, a channelplate detector records low energy electrons emerging from the collision volume.