Role of the ground state in electron-atom double ionization

Area of Science:

• Atomic Physics
• Quantum Mechanics
• Electron-Impact Ionization

Background:

• Absolute measurements of helium double ionization by 5.6 keV electron impact have been reported.
• The first Born approximation is typically considered valid at such high impact energies.
• Previous theoretical calculations using a Faddeev-type approach questioned the validity of the first Born approximation.

Purpose of the Study:

• To re-evaluate the validity of the first Born approximation for high-energy electron-impact double ionization of helium.
• To address the discrepancy between theoretical predictions and experimental measurements.
• To identify the cause of the disagreement in previous studies.

Main Methods:

• Theoretical analysis based on the first Born approximation.
• Re-examination of the atomic helium ground state description in theoretical models.
• Comparison of theoretical results with existing experimental data.

Main Results:

• The first Born approximation is confirmed to be valid for 5.6 keV electron-impact ionization of helium.
• The discrepancy with experimental measurements is attributed to an inadequate representation of the helium ground state in prior calculations.
• Accurate description of the ground state resolves the disagreement.

Conclusions:

• The first Born approximation remains a valid theoretical tool for high-energy electron-impact ionization processes.
• Accurate initial state wavefunctions are crucial for reliable theoretical predictions in atomic collision physics.
• This work clarifies the applicability of fundamental approximations in atomic ionization studies.