Three-body Coulomb problem probed by mapping the Bethe surface in ionizing ion-atom collisions

Area of Science:

• Atomic and Molecular Physics
• Quantum Mechanics
• Collision Physics

Background:

• The three-body Coulomb problem is fundamental in atomic physics.
• Understanding single ionization of atoms like helium is crucial for various applications.
• Previous theoretical models have limitations in describing complex collision dynamics.

Purpose of the Study:

• To experimentally investigate the kinematically complete single ionization of helium.
• To map low-energy electron emission as a function of projectile deflection.
• To compare experimental results with state-of-the-art theoretical predictions.

Main Methods:

• Utilizing kinematically complete experiments for helium ionization.
• Employing 100 MeV/u C(6+) and 3.6 MeV/u Au(53+) ion impact.
• Mapping low-energy electron emission (E(e)<150 eV) with high angular resolution (Δθ(p)±25 nrad).

Main Results:

• Detailed mapping of the Bethe surface for electron emission.
• Observation of ionization at extremely large impact parameters (≈10x He K-shell radius) for Au(53+) impact.
• Significant disagreement between experimental data and continuum distorted wave-eikonal initial state (CDW-EIS) theory.

Conclusions:

• Current theoretical models, including CDW-EIS, are insufficient to accurately describe the observed electron emission in the three-body Coulomb problem.
• The study highlights the need for refined theoretical approaches to handle high-perturbation ionization scenarios.
• Experimental data provide critical benchmarks for future theoretical developments in atomic collision physics.