Ultracold Anions for High-Precision Antihydrogen Experiments.

Area of Science:

• Atomic and Molecular Physics
• Antimatter Physics
• Laser Spectroscopy

Background:

• Precise measurements of matter-antimatter symmetry and antimatter gravity necessitate ultracold antihydrogen.
• Laser-cooled anions offer a promising method for precooling antiprotons to achieve ultracold anti-atoms.
• Few anion candidates possess suitable transitions for effective laser cooling due to weak electron binding.

Purpose of the Study:

• To fully characterize the binding energies, transition rates, and branching ratios of lanthanum anions (La^{-}) as a laser cooling candidate.
• To experimentally and theoretically determine the suitability of La^{-} for precooling antiprotons.

Main Methods:

• Combined transverse and collinear laser spectroscopy were employed to measure the laser cooling transition frequency and rate.
• A novel high-precision theoretical treatment was utilized to calculate unmeasured energy levels, transition rates, branching ratios, and lifetimes.
• Experimental and theoretical data were integrated to provide a comprehensive understanding of the La^{-} laser cooling cycle.

Main Results:

• The resonant frequency of the La^{-} laser cooling transition was determined to be 96.592713(91) THz.
• The transition rate was measured at 4.90(50) × 10^4 s^{-1}, significantly stronger than previously predicted.
• Theoretical calculations provided complementary data on energy levels and transition properties, confirming experimental findings.

Conclusions:

• Lanthanum anions (La^{-}) are established as a suitable system for laser cooling.
• The strong laser cooling transition of La^{-} enhances its potential for producing ultracold antihydrogen.
• This research advances the development of techniques for high-precision antimatter experiments.