Lifetimes of superdeformed rotational states in 36^{36}Ar

Lifetimes have been measured in a superdeformed rotational band recently identified in the [Formula Presented] nucleus [Formula Presented] A large low-spin quadrupole deformation [Formula Presented] is confirmed and a decrease in the collectivity is observed as the high-spin band termination at [Formula Presented] is approached. Detailed comparisons of the experimental [Formula Presented] values with the results of cranked Nilsson-Strutinsky and large-scale [Formula Presented] spherical shell model calculations indicate the need for a more refined treatment of transition matrix elements close to termination in the former, and the inclusion of the complete [Formula Presented] model space in the latter description of this highly-collective rotational band

Dipole and quadrupole moments of 73−78^{73-78}Cu as a test of the robustness of the Z=28Z=28 shell closure near 78^{78}Ni

International audienceNuclear spins and precise values of the magnetic dipole and electric quadrupole moments of the ground states of neutron-rich Cu73–78 isotopes were measured using the Collinear Resonance Ionization Spectroscopy (CRIS) experiment at the CERN On-Line Isotope Mass Separator (ISOLDE) facility. The nuclear moments of the less exotic Cu73,75 isotopes were remeasured with similar precision, yielding values that are consistent with earlier measurements. The moments of the odd-odd isotopes, and 2978Cu (N=49) in particular, are used to investigate excitations of the assumed doubly magic Ni78 core through comparisons with large-scale shell-model calculations. Despite the narrowing of the Z=28 shell gap between N∼45 and N=50, the magicity of Z=28 and N=50 is restored toward Ni78. This is due to weakened dynamical correlations, as clearly probed by the present moment measurements