Direct Observation of Competing M1 and M3 Transitions in ^{10}B

Area of Science:

• Nuclear Physics
• Atomic and Molecular Physics

Background:

• Understanding nuclear structure and decay properties is crucial for nuclear physics.
• Boron-10 (¹⁰B) is a light nucleus with complex excitation spectra.
• Isobaric analog states (IAS) provide insights into nuclear structure and isospin symmetry.

Purpose of the Study:

• To investigate the gamma decay of excited states in Boron-10 (¹⁰B).
• To observe and characterize weak gamma-ray transitions, including M1 and M3 transitions from the IAS.
• To compare experimental findings with ab initio no-core shell model calculations.

Main Methods:

• Populating excited states in ¹⁰B via the ¹⁰B(p,p'γ)¹⁰B* reaction at 8.5 MeV.
• Utilizing coincidence gamma-ray spectroscopy with LaBr₃:Ce and CeBr₃ detectors in anti-Compton shields.
• Measuring branching ratios with high sensitivity (λ≥10⁻⁴).

Main Results:

• Observed weak gamma-ray transitions, including M3 and E2 transitions involving the IAS.
• For the first time in ¹⁰B, observed competing M1 and M3 transitions from the decay of the IAS.
• Experimental branching ratios and reduced transition probabilities were measured.

Conclusions:

• The study successfully observed previously unobserved gamma transitions in ¹⁰B.
• Experimental results show reasonable agreement with ab initio no-core shell model calculations.
• The findings contribute to a better understanding of nuclear structure and decay in light nuclei.