Speaker
Description
Neutron-rich nuclei around A$\sim$100 present intriguing cases in nuclear structure due to their significant deformation and complex shapes, including predicted triaxiality as well as rare oblate-deformed ground states. These features pose challenges for theoretical models, especially in describing the abrupt shape transitions observed between N = 58 and 60. Even-even nuclei in this region exhibit low-lying excited states characteristic of collective rotational behavior, where both axial symmetry and triaxiality are essential to understanding their structural evolution. For example, Coulomb-excitation studies on 110Ru indicate pronounced triaxiality, whereas decay spectroscopy on 106,108Mo suggests a more axially symmetric shape.
In contrast, odd-odd nuclei remain less well understood due to limited experimental data on spin and parity. The Gallagher–Moszkowski (GM) rule is relevant for describing energetically favoured nucleon spin couplings; however, many nuclei have uncertain or inconsistent assignments. For example, recent work on 106Nb has revised long-standing ground-state properties, with unpublished data suggesting similar cases are widespread.
To address these uncertainties, detailed $\gamma$-ray and conversion-electron coincidence measurements are essential for establishing level schemes and constraining spin-parity assignments. An experiment was conducted in June 2025 at the LOHENGRIN recoil mass spectrometer at the Institut Laue–Langevin, Grenoble, using neutron-induced fission of 241Pu. Fission fragments were detected with Clover HPGe and silicon detectors, enabling high-resolution spectroscopy well suited to these studies.
Preliminary results from this experiment will be presented, including newly identified transitions and updated level schemes for nuclei in the A = 100–104 mass region. These data provide new insights into nuclear structure and proton–neutron coupling in deformed, odd-odd systems in this region.
