Fragmentation of Positronium (Ps) in collision with Li ion

TL;DR

This study investigates the fragmentation of ground state ortho Positronium during collision with Li+ ions using a Coulomb distorted eikonal approximation, revealing energy spectrum shifts and e-e+ asymmetry influenced by two-center effects.

Contribution

It introduces a detailed model accounting for two-center effects in Ps fragmentation during Li+ collisions, analyzing differential cross sections at various energies.

Findings

Observation of a broad electron loss peak around v_e ~ v_p

Shift of the DDCS peak towards higher ejection energy

Strong e-e+ energy spectrum asymmetry

Abstract

Fragmentation of ground state ortho Positronium (Ps) in collision with Li ion (Li+) is studied in the framework of post collisional Coulomb distorted eikonal approximation (CDEA) for the target elastic case . The present model takes account of the two center effect on the ejected e which is crucial for a proper description of the projectile ionization involving an ionic target. Both the fully differential (TDCS) and the doubly differential (DDCS) cross sections (energy spectra) are investigated at intermediate and high incident energies. A broad distinct Electron loss peak (ELP) centered around v_e ~ v_p is noted in the e energy spectrum in contrast to the sharp ELP for a heavy projectile. Two salient features are noted in the present study: i) the shift of the e DDCS peak (summed over e+ angles) towards higher ejection energy with respect to half the residual energy of the system, ii) comparison of the e& e+ energy spectra reflect a strong e - e+ asymmetry with respect to the ratio v_e/v_p =1 >. Both these features could be attributed to the post collisional two center effect on the e due to its parent nucleus (e+) and the screened target ion . Two different wave functions of the Li ion are chosen in order to test the sensitivity of the present results with respect to the choice of the wave function.