Complete break-up of the helium atom by proton and antiproton impact

TL;DR

This paper introduces a comprehensive ab initio, non-perturbative method to analyze helium ionization caused by proton and antiproton impacts, achieving accurate results across a wide energy spectrum and providing detailed electron ejection data.

Contribution

It presents a novel time-dependent approach with a finite-element discretization to accurately model helium ionization by charged particle impact, validated against experimental data.

Findings

Good agreement with experimental cross sections over 3 keV to 6 MeV

Predicted angle-differential cross sections at 6 MeV proton impact

Visualized electron density evolution during ionization process

Abstract

We present a fully {\it ab initio}, non-perturbative, time-dependent approach to describe single and double ionization of helium by proton and antiproton impact. A flexible and accurate finite-element discrete-variable-representation is applied to discretize the problem on the radial grid in spherical coordinates. Good agreement with the most recent experimental data for absolute angle-integrated cross sections is obtained over a wide range of incident projectile energies between 3 keV and 6 MeV. Furthermore, angle-differential cross sections for two-electron ejection are predicted for a proton impact energy of 6 MeV. Finally, the time evaluation of the ionization process is portrayed by displaying the electron density as a function of the projectile location.