Speaker
Description
The germanium nuclei have been of recent interest for several reasons. First, $^{76}$Ge is one of the leading candidates for the observation of neutrinoless double-beta decay. Thus, detailed understanding of the structure is important for improving the nuclear matrix element calculation for the process in order for the half-life to be extracted. Knowledge of the entire isotopic chain is beneficial in this respect. In addition, the structure of the Ge nuclei has many interesting features. Open questions of triaxiality and shape coexistence remain.
In order to better understand the structures of these nuclei, we have undertaken studies of $^{76,74,72}$Ge using inelastic neutron scattering (INS) at the University of Kentucky Accelerator Laboratory. INS provides non-selective, statistical population of the low-lying, low-spin states, including non-yrast states, allowing characterization of the comprehensive level scheme. Moreover, the Doppler-shift attenuation method following INS is utilized to measure level lifetimes in the femtosecond regime. Overall, the method allows the extraction of gamma-ray energies, level energies, level lifetimes, $a_2$ and $a_4$ angular distribution coefficients, branching ratios, and multipole mixing ratios. These data can then be used to calculate reduced transition probabilities which can be compared to theoretical calculations to further our understanding.
The focus of this presentation will be $^{72,74}$Ge. A number of new structural features have been identified and characterized in each nucleus, including the first observation of shape coexistence in the Ge nuclei in $^{74}$Ge. Large-scale shell-model calculations have also been performed and show remarkable agreement with experimental data.
This material is based upon work supported by the U. S. National Science Foundation under Grant No. PHY-2209178, 2514845, and 2110365.
| Contribution category | Experiment |
|---|---|
| Presenter status | Faculty/Staff |