Total and Inelastic Positron Scattering Cross Sections

Abstract

Values are presented of the total cross sections (TCS) for positrons and electrons colliding with the hydrocarbons CH4, C2H2, C2H4, C2H6 and C6H6, the polar molecules H2O and NH3 and also CF4, CC14, SiH4 and O2,which have recently been measured in our laboratory. A simple method for measuring the cross section for positronium (Ps) formation is demonstrated for these molecules. In the next subsection a brief comment on TCS is added. Considerable interest is nowadays concentrated on inelastic collision studies. We treat experimentally the inelastic cross section for the Schumann-Runge excitation in O2 by positron and electron impact, and inelastic collisions with other molecules. Methods for narrowing the beam energy were tried and demonstrations were performed for several inelastic collisions. Theoretical calculations of total cross sections (elastic and absorption) for CH4, SiH4, H2O and NH3 have been made by Jainl and are reported elsewhere in these Proceedings.