Speaker
Description
The evolution of shell structure in neutron-rich nuclei remains a central question in nuclear structure physics. In isotopes with N = 50, from 90Zr to 78Ni, specific excited states are predominantly associated with neutron excitations across the N = 50 shell gap. The systematic study of their excitation energies, particularly in 82Ge, provides direct insight into the evolution of the N = 50 gap. Moreover, spectroscopy of odd-mass Ge isotopes near N = 50 offers valuable information on the evolution of single-particle and collective configurations, and on the role of particle–hole excitations across the shell gap.
In this work, we investigate neutron-rich Ge and Zn isotopes located at the boundary of this key structural region. The experiment was performed at GANIL using the AGATA γ-ray tracking array coupled to the VAMOS++ spectrometer. Neutron-rich nuclei were produced via fusion–fission reactions induced by a 238U beam at 6.2 MeV/u impinging a 9Be target. Fission fragments were unambiguously identified in mass (A) and atomic number (Z) using VAMOS++, while prompt γ rays were detected in coincidence with the fragments by AGATA, composed of eight triple clusters.
Although these nuclei have previously been studied through β-decay, Coulomb excitation, and nucleon-transfer experiments, their high-spin structures remained unexplored using prompt γ-ray spectroscopy. A detailed analysis of the present data allows us, for the first time, to propose level schemes for several neutron-rich Ge isotopes (N = 47, 49, and 51) and Zn isotopes (N = 47 and 49), including the identification of high-spin states.
The experimental results will be presented and discussed in comparison with shell-model calculations employing the most advanced effective interactions developed for this region of the nuclear chart.