Calculating the Annihilation Parameters for the Interaction of

Abstract

One of the most important events happens when positrons interact with atoms is the annihilation process of the positronium (e-+e+) atom, which is a probable structure, forming during the interaction. We have extended our previous work on the partial wave approximation, to the treatment of annihilation process for positron-atom system in the elastic scattering region. We have use a formula of annihilation parameter (Zeff) proposed by Gribakin (Phys.Rev.A,61,22720(200)) depending in it’s general formula on Phase shift, which in turn had calculated using the Polarized Orbital method, whereas our method in calculating that factor was the Partial Wave method. Good agreement is obtained between our results and those of Gribakin concerning (Zeff), also we calculate the annihilation rate ( ), and the annihilation cross section ( ), where both depends on (Zeff) in explicit mathematical formulas.