Positron Scattering and Interaction Dynamics

Positron scattering and interaction dynamics encompass the processes by which positrons—antiparticles of electrons—encounter matter, exchange energy and momentum, form transient bound states, and ultimately annihilate. Key observables include differential and total scattering cross sections, positron binding energies to atoms or molecules, and annihilation rates, all of which depend sensitively on projectile energy, target structure and many-body correlation effects. At low impact energies, long-range polarisation and virtual positronium formation dominate, whereas at higher energies inelastic channels such as ionisation and excitation become important. Advances in theory and computation now allow for near-quantitative predictions of positron interaction parameters, facilitating the interpretation of experimental measurements in fields as diverse as materials characterisation, surface science, fundamental antimatter physics and medical imaging technologies such as positron emission tomography (PET). This synergy between theory and experiment drives both improved diagnostic techniques and deeper understanding of electron-positron correlations in molecular and condensed-matter systems.

Research from Nature Portfolio

Recent studies have harnessed machine-learning wavefunctions and many-body theory to achieve unprecedented accuracy in positron–molecule interactions. A neural network variational Monte Carlo approach has been shown to yield state-of-the-art ground-state energies and positron binding characteristics across a range of atoms and small molecules without reliance on conventional basis sets, reproducing experimental benzene binding energies and annihilation rates with high fidelity. Complementary many-body theoretical developments have provided a unified framework for polarisation, screening and virtual positronium formation that predicts binding energies to within one per cent of measured values, elucidates the enhanced annihilation rates in polar versus nonpolar molecules, and lays the groundwork for future extension to scattering cross-section and γ-ray spectrum calculations.

Research from all publishers

Ab initio many-body theory combined with shifted pseudostate methods has recently delivered accurate positron scattering and annihilation rates for diatomic and small polyatomic molecules such as H₂, N₂ and CH₄, highlighting the crucial role of positron-molecule correlations in achieving agreement with experimental data. In parallel, classical trajectory Monte Carlo simulations of positron impact on H₂ have mapped ionisation cross sections over 20–1000 eV, yielding total and single-differential cross sections in good accord with measurements and offering insight into angle- and energy-resolved ejecta distributions. These disparate approaches together underscore progress in bridging low-energy quantum effects and high-energy collision dynamics, informing both fundamental scattering theory and practical applications in material analysis and radiation transport modelling.

Positron Scattering and Interaction Dynamics publication trend

The graph below shows the total number of articles in positron scattering and interaction dynamics across all publications each year (not limited to Nature Index journals).

Technical terms

Scattering cross section: A quantitative measure of the probability that a positron will scatter from, ionise or excite a target particle under specified conditions.

Annihilation rate: The frequency at which positrons annihilate with electrons in a material, often inferred from the intensity of resulting γ-ray emission.

Many-body correlation: Interactions among multiple charged particles—including electrons and the positron—leading to collective polarisation, screening and virtual positronium formation that profoundly influence scattering and binding phenomena.

Virtual positronium formation: A transient process in which a molecular electron temporarily binds to the positron, enhancing interaction strength and annihilation likelihood.

References

1. Neural network variational Monte Carlo for positronic chemistry. Nature Communications (2024).
2. Many-body theory of positron binding to polyatomic molecules. Nature (2022).
3. Many-Body Theory Calculations of Positron Scattering and Annihilation in H2, N2, and CH4. Physical Review Letters (2023).
4. Ionization Cross Sections of Hydrogen Molecule by Electron and Positron Impact. International Journal of Molecular Sciences (2024).