Testing Strong-Field QED to Second Order in the Highly Correlated Atomic System Berylliumlike Pb^{78+} by...

Area of Science:

• Atomic, Molecular, and Optical Physics
• Quantum Electrodynamics (QED)
• Heavy-Ion Physics

Background:

• Studying electron-ion recombination is crucial for understanding atomic structure and fundamental physics.
• Few-electron heavy ions provide unique testing grounds for QED effects due to high nuclear charge.

Purpose of the Study:

• To perform high-resolution electron-ion collision spectroscopy on heavy, few-electron ions.
• To precisely measure the resonant electron-ion recombination of berylliumlike Pb^{78+} ions.
• To determine the excitation energy of Pb^{78+} and compare it with theoretical predictions.

Main Methods:

• Coupling a low-energy storage ring with an ultracold electron cooler and a heavy-ion accelerator.
• Measuring resonant electron-ion recombination in the collision-energy range of 9.3-16.5 eV.
• Utilizing high-resolution spectroscopy techniques for precise measurements.

Main Results:

• Precisely determined the excitation energy of berylliumlike Pb^{78+} (2s^{2} S_{0}-2s2p P_{1}) to be 244.937(30) eV.
• Achieved agreement with the most recent theoretical value calculated with rigorous strong-field QED up to the second order.
• Demonstrated the capability of the experimental setup for high-precision atomic structure measurements.

Conclusions:

• The experimental results validate advanced theoretical calculations in QED for highly charged ions.
• The study highlights the potential for achieving even higher experimental accuracy (an order of magnitude) with further technical improvements.
• This work advances the field of electron-ion collision spectroscopy for the heaviest few-electron ions.