${}^{78}$Ni revealed as a doubly magic stronghold against nuclear deformation

Abstract

Nuclear magic numbers, which emerge from the strong nuclear force based on quantum chromodynamics, correspond to fully occupied energy shells of protons, or neutrons inside atomic nuclei. Doubly magic nuclei, with magic numbers for both protons and neutrons, are spherical and extremely rare across the nuclear landscape. While the sequence of magic numbers is well established for stable nuclei, evidence reveals modifications for nuclei with a large proton-to-neutron asymmetry. Here, we provide the first spectroscopic study of the doubly magic nucleus ${}^{78}$Ni, fourteen neutrons beyond the last stable nickel isotope. We provide direct evidence for its doubly magic nature, which is also predicted by ab initio calculations based on chiral effective field theory interactions and the quasi-particle random-phase approximation. However, our results also provide the first indication of the breakdown of the neutron magic number 50 and proton magic number 28 beyond this stronghold, caused by a competing deformed structure. State-of-the-art phenomenological shell-model calculations reproduce this shape coexistence, predicting further a rapid transition from spherical to deformed ground states with ${}^{78}$Ni as turning point.

References in corpus (30)

• Modern Theory of Nuclear Forces
• The Shell Model as Unified View of Nuclear Structure
• Improved nuclear matter calculations from chiral low-momentum interactions
• Novel features of nuclear forces and shell evolution in exotic nuclei
• Three-body forces and the limit of oxygen isotopes
• The In-Medium Similarity Renormalization Group: A Novel Ab Initio Method for Nuclei
• Three-body forces: From cold atoms to nuclei
• Collapse of the N=28 shell closure in ${}^{42}$Si
• A nucleus-dependent valence-space approach to nuclear structure
• In-Medium Similarity Renormalization Group for Nuclei
• Identification and Separation of Radioactive Isotope Beams by the BigRIPS Separator at the RIKEN RI Beam Factory
• Structure of the lightest tin isotopes
• Nonperturbative shell-model interactions from the in-medium similarity renormalization group
• Saturation with chiral interactions and consequences for finite nuclei
• Novel shape evolution in exotic Ni isotopes and configuration-dependent shell structure
• DALI2: A NaI(Tl) detector array for measurements of $\gamma$ rays from fast nuclei
• In-Medium Similarity Renormalization Group for Open-Shell Nuclei
• Half Life of the Doubly-magic r-Process Nucleus 78Ni
• Evolution of the N=50 shell gap energy towards ${}^{78}$Ni
• Role of deformation on giant resonances within the QRPA approach and the Gogny force
• The Magnus expansion and the in-medium similarity renormalization group
• High-precision mass measurements of nickel, copper, and gallium isotopes and the purported shell closure at N=40
• Structure of ${}^{78}$Ni from first principles computations
• Shape Coexistence in 78 Ni and the new Island of Inversion
• Ground and excited states of doubly open-shell nuclei from ab initio valence-space Hamiltonians
• The N = 16 spherical shell closure in 24O
• How magic is the magic 68Ni nucleus?
• Coulomb exchange and pairing contributions in nuclear Hartree-Fock-Bogoliubov calculations with the Gogny force
• Isomer shift and magnetic moment of the long-lived 1/2${}^{+}$ isomer in ${}_{30}^{79}$Zn${}_{49}$: signature of shape coexistence near ${}^{78}$Ni
• Dipole and quadrupole moments of ${}^{73-78}$Cu as a test of the robustness of the $Z=28$ shell closure near ${}^{78}$Ni

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• Pseudospin Symmetry: Microscopic origin of the ground-state inversion in neutron-rich odd-A Cu isotopes
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