High-Precision Spectroscopy of ^{20}O Benchmarking Ab Initio Calculations in Light Nuclei

Area of Science:

• Nuclear Physics
• Spectroscopy
• Quantum Chemistry

Background:

• Investigating the properties of unstable nuclei is crucial for understanding nuclear structure.
• Oxygen-20 (20O) is an unstable isotope whose excited states provide insights into nuclear forces.

Purpose of the Study:

• To investigate the excited states of unstable Oxygen-20.
• To determine lifetimes, B(E2) and B(M1) values for specific states.
• To compare experimental data with ab initio calculations from chiral effective field theory.

Main Methods:

• Gamma-ray spectroscopy following the 19O(d,p)20O reaction.
• Doppler shift attenuation method for lifetime measurements.
• Determination of branching ratios and E2/M1 mixing ratios.

Main Results:

• Lifetimes of the 2+ and 3+ excited states in 20O were precisely measured.
• Reduced transition probabilities B(E2) and B(M1) were determined.
• Ab initio calculations using chiral effective field theory Hamiltonians were compared with experimental data.

Conclusions:

• Ab initio approaches based on chiral effective field theory are challenged by high-precision spectroscopic properties of nuclei.
• Reduced transition probabilities serve as a stringent test for the performance of ab initio models.
• This study represents the first comparison of detailed spectroscopic properties with ab initio calculations for a nucleus far from stability.