Positron scattering and annihilation on noble gas atoms

Abstract

Positron scattering and annihilation on noble gas atoms below the positronium formation threshold is studied ab initio using many-body theory methods. The many-body theory provides a near-complete understanding of the positron-noble-gas-atom system at these energies and yields accurate numerical results. It accounts for positron-atom and electron-positron correlations, e.g., polarization of the atom by the incident positron and the non-perturbative process of virtual positronium formation. These correlations have a large effect on the scattering dynamics and result in a strong enhancement of the annihilation rates compared to the independent-particle mean-field description. Computed elastic scattering cross sections are found to be in good agreement with recent experimental results and Kohn variational and convergent close-coupling calculations. The calculated values of the annihilation rate parameter $Z_{\mathrm{eff}}$ (effective number of electrons participating in annihilation) rise steeply along the sequence of noble gas atoms due to the increasing strength of the correlation effects, and agree well with experimental data.

24 pages, 17 figures

References in corpus (3)

• Positron-molecule interactions: resonant attachment, annihilation, and bound states
• Many-body theory of positron-atom interactions
• Positron-atom scattering using pseudo-state energy shifts

Cited by in corpus (9)

• Recent progress in the description of positron scattering from atoms using the Convergent Close-Coupling Theory
• Model-potential calculations of positron binding, scattering, and annihilation for atoms and small molecules, using a Gaussian basis
• Mode coupling and multiquantum vibrational excitations in Feshbach-resonant positron annihilation in molecules
• Calculations of positronium-atom scattering using a spherical cavity
• Positron cooling and annihilation in noble gases
• Effective radius of ground- and excited-state positronium in collisions with hard walls
• Probing positron cooling in noble gases via annihilation $\gamma$ spectra
• Comment on "Gamma-ray spectra from low-energy positron annihilation processes in molecules"
• Ground-state energy of quasi-free positrons in non-polar fluids