Binding Energy of 79Cu: Probing the Structure of the Doubly Magic 78Ni from Only One Proton Away

High-precision masses of ⁷⁵⁻⁷⁹Cu, giving the first accurate look at the mass surface one proton away from ⁷⁸Ni and supporting a doubly magic character for that nucleus.

Copper ions were produced at ISOLDE, cleaned in ISOLTRAP’s MR-ToF spectrometer, and measured in the Penning trap with ToF-ICR. The new masses are between 5 and 100 times more precise than earlier magnetic-dipole values and are compared with large-scale shell-model calculations (PFSDG-U).

⁷⁸Ni is a benchmark for how magic numbers survive far from stability. The ⁷⁹Cu binding energy, together with a companion spectroscopy paper, is the result CERN Courier later covered as copper revealing nickel’s doubly magic nature.