Interplay between nuclear shell evolution and shape deformation revealed by magnetic moment of 75Cu

Abstract

Exotic nuclei are characterized by a number of neutrons (or protons) in excess relative to stable nuclei. Their shell structure, which represents single-particle motion in a nucleus, may vary due to nuclear force and excess neutrons, in a phenomenon called shell evolution. This effect could be counterbalanced by collective modes causing deformations of the nuclear surface. Here, we study the interplay between shell evolution and shape deformation by focusing on the magnetic moment of an isomeric state of the neutron-rich nucleus 75Cu. We measure the magnetic moment using highly spin-controlled rare-isotope beams and achieving large spin alignment via a two-step reaction scheme that incorporates an angular-momentum-selecting nucleon removal. By combining our experiments with numerical simulations of many-fermion correlations, we find that the low-lying states in 75Cu are, to a large extent, of single-particle nature on top of a correlated 74Ni core. We elucidate the crucial role of shell evolution even in the presence of the collective mode, and within the same framework, we consider whether and how the double magicity of the 78Ni nucleus is restored, which is also of keen interest from the perspective of nucleosynthesis in explosive stellar processes.

10 pages, 4 figures

References in corpus (10)

• The Shell Model as Unified View of Nuclear Structure
• Novel features of nuclear forces and shell evolution in exotic nuclei
• New effective interaction for $pf$-shell nuclei and its implications for the stability of the $N$=$Z$=28 closed core
• Collapse of the N=28 shell closure in ${}^{42}$Si
• Novel shape evolution in exotic Ni isotopes and configuration-dependent shell structure
• Structure of ${}^{78}$Ni from first principles computations
• Shape Coexistence in 78 Ni and the new Island of Inversion
• The Sensitivity of Core-Collapse Supernovae to Nuclear Electron Capture
• Dipole and quadrupole moments of ${}^{73-78}$Cu as a test of the robustness of the $Z=28$ shell closure near ${}^{78}$Ni
• Production of spin-controlled rare isotope beams

Cited by in corpus (9)

• Toward the discovery of matter creation with neutrinoless double-beta decay
• The Neutron-Rich Edge of the Nuclear Landscape. Experiment and Theory
• Level Structures of ${}^{56,58}$Ca Cast Doubt on a doubly magic ${}^{60}$Ca
• Moments and Radii of exotic Na and Mg isotopes
• High-precision measurements of low-lying isomeric states in ${}^{120-124}$In with JYFLTRAP double Penning trap
• Magnetic moments of short-lived nuclei with part-per-million accuracy: Towards novel applications of $\beta$-detected NMR in physics, chemistry and biology
• Fast-timing study of ${}^{81}$Ga from the $\beta$ decay of ${}^{81}$Zn
• Pseudospin Symmetry: Microscopic origin of the ground-state inversion in neutron-rich odd-A Cu isotopes
• Extreme Shape Coexistence Observed in ${}^{70}$Co