The low-energy positron scattering upon endohedrals

TL;DR

This paper studies how endohedral fullerenes affect positron scattering, revealing significant changes in scattering behavior due to polarization effects and virtual positronium formation, using new simplified computational approaches.

Contribution

It introduces novel simplified methods to incorporate fullerene polarizability and virtual positronium effects into positron scattering calculations on endohedrals.

Findings

Polarization of fullerene shells significantly alters scattering phases.

Virtual positronium formation impacts scattering cross-sections.

Endohedral effects cause strong variations in scattering characteristics.

Abstract

We investigate positron scattering upon endohedrals and compare it with electron-endohedral scattering. We show that the polarization of the fullerene shell considerably alters the polarization potential of an atom, stuffed inside a fullerene. This essentially affects both the positron and electron elastic scattering phases as well as corresponding cross-sections. Of great importance is also the interaction between the incoming positron and the target electrons that leads to formation the virtual positronium. We illustrate the general trend by concrete examples of positron and electron scattering upon endohedrals He@C60 and Ar@C60, and compare it to scattering upon fullerene C60. To obtain the presented results, we have employed new simplified approaches that permit to incorporate the effect of fullerenes polarizability into the He@C60 and Ar@C60 polarization potential and to take into account the virtual positronium formation. Using these approaches, we obtained numeric results that show strong variations in shape and magnitudes of scattering phases and cross-sections due to effect of endohedral polarization and virtual positronium formation.