Fully Correlated Electronic Dynamics for Antiproton Impact Ionization of Helium

TL;DR

This study uses a non-perturbative method to calculate helium ionization cross sections due to antiproton impact, revealing new insights into electron correlations and confirming experimental anomalies at high energies.

Contribution

The paper introduces a fully correlated, non-perturbative time-dependent approach to accurately model electron dynamics in helium ionization by antiprotons, especially at high energies.

Findings

Excellent agreement with experimental data at high energies

Discrepancies observed at lower impact energies

Double-to-single ionization ratio is twice as large for antiprotons at 1 MeV

Abstract

We present total cross sections for single and double ionization of helium by antiproton impact over a wide range of impact energies from 10 keV/amu to 1 MeV/amu. A non-perturbative time-dependent close-coupling method (TDCC) is applied to fully treat the correlated dynamics of the ionized electrons. Excellent agreement is obtained between our calculations and experimental measurements of total single and double ionization cross sections at high impact energies, whereas for lower impact energies, some discrepancies with experiment are found. At an impact energy of 1 MeV we also find that the double-to-single ionization ratio is twice as large for antiproton impact as for proton impact, confirming a long-standing unexpected experimental measurement.