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Low-Energy-Positron Scattering by Acetone.

Rafael O Lima1, Giseli M Moreira1, Márcio H F Bettega1

  • 1Departamento de Fı́sica, Universidade Federal do Paraná, Caixa Postal 19044, Curitiba, Paraná 81531-980, Brazil.

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Calculations show low-energy positron collisions with acetone molecules. Results align with recent experimental data, improving agreement below the positronium formation threshold.

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Area of Science:

  • Atomic and Molecular Physics
  • Quantum Scattering Theory
  • Computational Chemistry

Background:

  • Positron scattering by molecules is crucial for understanding matter-antimatter interactions.
  • Acetone (C3H6O) is a polar molecule with limited experimental data on low-energy positron collisions.
  • Discrepancies exist in existing experimental total cross-section data for positron-acetone interactions below 2 eV.

Purpose of the Study:

  • To perform theoretical calculations for elastic positron-acetone collisions.
  • To investigate positron scattering dynamics in the low-energy range (10^-4 to 10 eV).
  • To compare theoretical results with available experimental data for validation.

Main Methods:

  • Employed the Schwinger multichannel method in a static plus polarization approximation.
  • Incorporated the effect of long-range dipole interaction using the Born-closure scheme.
  • Calculated integral cross sections for positron-acetone elastic scattering.

Main Results:

  • Theoretical integral cross sections were computed for positron-acetone elastic collisions.
  • Results show qualitative agreement with the most recent experimental total cross sections across all energy ranges.
  • Quantitative agreement significantly improves below the positronium formation threshold upon correction for experimental angular resolution.

Conclusions:

  • The theoretical model provides a reliable description of low-energy positron scattering by acetone.
  • The study highlights the importance of accounting for molecular polarization and dipole interactions.
  • Improved agreement with corrected experimental data validates the computational approach.