Differential electron emission for single and multiple ionization of argon by 500 eV positrons

Area of Science:

• Atomic and Molecular Physics
• Quantum Mechanics
• Plasma Physics

Background:

• Positron-atom collisions are crucial for understanding fundamental interactions.
• Previous studies have explored electron emission in such collisions, but detailed triply differential cross sections are less understood.
• Argon serves as a relevant target atom for studying ionization processes.

Purpose of the Study:

• To measure triply differential electron emission cross sections for single ionization of argon by 500 eV positrons.
• To compare experimental data with theoretical models, specifically cosine squared representations of binary and recoil scattering.
• To present singly differential electron emission data for double and triple ionization events.

Main Methods:

• Experimental measurement of electron emission cross sections using coincidence detection.
• Scattering of 500 eV positrons off argon atoms.
• Detection of scattered positrons at a specific angle (3 degrees) and emitted electrons within a defined energy range (<10 eV) and angular distribution (45-135 degrees).
• Convolution of theoretical models (cosine squared representations) with experimental parameters for comparison.

Main Results:

• Detailed triply differential electron emission cross sections were obtained for single ionization.
• Comparison with theoretical models revealed discrepancies, particularly in the distribution of emitted electrons.
• Singly differential cross sections for double and triple ionization were also determined.

Conclusions:

• The study provides valuable experimental data for single ionization of argon by positrons.
• The comparison highlights the need for refined theoretical models to accurately describe electron emission dynamics.
• The data contributes to a deeper understanding of positron-induced atomic ionization processes.