Abstract
The size of a excitation strength has been determined for the first time in a predominantly axially deformed even-even nucleus. It has been obtained from the observation of a rare -mixing situation between two close-lying states of the nucleus with components characterized by intrinsic projection quantum numbers and . Nuclear resonance fluorescence induced by quasimonochromatic linearly polarized -ray beams provided evidence for mixing of the states at 3159.1(3) and 3173.6(3) keV in excitation energy from their -decay branching ratios into the ground-state band. The transition strength of was inferred from a mixing analysis of their transition rates into the ground-state band. It is in agreement with predictions from the quasiparticle phonon nuclear model. This determination represents first experimental information on the excitation strength of a nuclear quantum state with a negative -symmetry quantum number.
- Received 27 April 2020
- Accepted 30 July 2020
DOI:https://doi.org/10.1103/PhysRevLett.125.092501
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