First Observation of Multiphonon γ-Vibrations in an Odd-Odd Nuclear System.

Area of Science:

• Nuclear Physics
• Nuclear Spectroscopy
• Nuclear Structure

Background:

• Studying exotic nuclei provides insights into nuclear forces and structure.
• Neutron-rich nuclei beyond N=60 are crucial for understanding shape transitions.
• High-spin states in odd-odd nuclei are challenging to access and interpret.

Purpose of the Study:

• To identify and characterize multiphonon gamma-vibrational bands in the odd-odd nucleus _{41}^{104}Nb_{63}.
• To investigate the coexistence of different nuclear shapes (triaxial and oblate) in this region.
• To test theoretical models against experimental data for high-spin states.

Main Methods:

• Utilized a spectrometer with isotopic resolution coupled to a gamma-ray tracking array.
• Performed high-fold gamma coincidence measurements.
• Employed triaxial projected shell model calculations.

Main Results:

• Successfully identified the first multiphonon gamma-vibrational bands in _{41}^{104}Nb_{63}.
• Observed good agreement between experimental data and theoretical calculations for yrast, one-phonon, and two-phonon bands.
• Investigated shape coexistence, suggesting both triaxial and oblate configurations.

Conclusions:

• Demonstrated the robustness of vibration excitations even with odd valence proton and neutron.
• Highlighted the possibility of coexisting shapes in nuclei beyond the N=60 transitional region.
• Advanced the understanding of nuclear structure in exotic, neutron-rich isotopes.