Information about TS-1 and TS-2 double ionization mechanisms for positron and electron impact ionization of argon

Ejected electron angular distributions are measured for single and double ionization of argon by 500 eV positron and electron impact. Double to single ionization ratios show marked differences as a function of projectile charge. Combinations of the positron and electron data and a simple double ionization model are used to obtain differential information about the TS-1 and TS-2 mechanisms. Our analysis suggests that both mechanisms contribute roughly equally to the emission of two electrons and that interference between the two mechanisms significantly alters the ejected electron spectra.