Nickel-56 not so doubly magic?

The magnetic dipole moment of Copper-57 was deduced in an experiment employing the Nuclear Magnetic Resonance (NMR) technique, which is similar-but superior in sensitivity-to Magnetic Resonance Imaging (MRI) employed in medicine.In this experiment, led by Kei Minamisono, Paul Mantica and collaborators, polarized Copper-57 ions were produced in the collision of a Nickel-58 primary beam and a Beryllium-9 target (at an angle of 2 degrees). The Copper-57 nuclei were magnetically separated from other species formed in the collision and subsequently delivered to the NMR apparatus. The magnetic dipole moment of this Copper isotope, which has just one proton more than doubly-magic N=Z=28 Nickel-56, was found to be only two nuclear magnetons, almost twice as small as predicted by theory under the assumption that Nickel-56 holds as an inert core. The result indicates a significant breaking of the N=Z=28 doubly closed-shell structure for Nickel-56.

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