Inner-shell Annihilation of Positrons in Argon, Iron and Copper Atoms

TL;DR

This paper presents ab initio calculations of positron annihilation parameters in Argon, Iron, and Copper atoms, focusing on shell-specific interactions below positronium formation thresholds.

Contribution

It introduces a combined computational approach using Cowan code and LSVM to accurately model positron-atom interactions and scattering cross sections.

Findings

Calculated annihilation parameters for different shells.

Comparison of effective charge with experimental data.

Computed s-wave scattering cross sections for Iron and Copper.

Abstract

The annihilation parameters of positrons with electrons in different shells of Argon, Iron and Copper atoms are calculated below the positronium (Ps) formation thresholds. Quite accurate ab initio calculations of the bound state wavefunctions of Argon, Iron and Copper orbitals are obtained from Cowan computer code. A least-squares variational method (LSVM) is used for determining the wavefunction of the positrons. The program is employed for calculating the s-wave partial cross sections of positrons scattered by Iron and Copper atoms. Our results of the effective charge are compared with available experimental and theoretical ones. --