Beyond the Point Ps Approximation

Abstract

In application to positron annihilation spectroscopy, Ps atom is considered not as a point particle, but as a finite size e+e- pair localized in a bubble-like state in a medium. It is shown that during transition from quasifree to localized state, variation of the internal Coulombic e+-e- attraction energy (several eV) plays an important role, which may govern Ps localization process.