Lifetime Measurements in (178)Hf.

Area of Science:

• Nuclear Physics
• Atomic and Molecular Physics

Background:

• Understanding nuclear structure and electromagnetic transitions is crucial in nuclear physics.
• The Hf-178 nucleus is a key subject for studying nuclear collective excitations and band structures.

Purpose of the Study:

• To measure nuclear level lifetimes in the 178Hf nucleus.
• To investigate collective transitions and band structures, particularly K(π)=2(+), K(π)=4(+), and K(π)=0(+) bands.
• To explore inter-band transitions and identify new collective phenomena.

Main Methods:

• Utilized the Gamma Ray Internal Conversion Electron (GRID) technique for precise lifetime measurements.
• Analyzed lifetimes of excited states within various K-bands.
• Calculated upper limits for absolute B(E2) values to assess transition strengths.

Main Results:

• Measured lifetimes for levels in K(π)=2(+), K(π)=4(+), and multiple K(π)=0(+) bands in 178Hf.
• Established a lower lifetime limit for the 4(+) level in the K(π)=4(+) band.
• Excluded collective transitions from the K(π)=4(+) band to the ground state band based on B(E2) values.
• Observed evidence for collective E2 transitions connecting two previously unobserved excited K(π)=0(+) bands.

Conclusions:

• The study provides new data on nuclear lifetimes and electromagnetic transitions in 178Hf.
• The findings constrain theoretical models of nuclear collective behavior.
• A novel instance of excited K(π)=0(+) bands linked by collective E2 transitions was identified, advancing the understanding of nuclear structure.