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Mass spectrometry, Nuclear many-body theory, Radioactive beams, Shell model, 59 ≤ A ≤ 89, Binding energy & masses, Nuclear structure & decays, Nucleon-nucleon interactions
Abstract:
Isomers close to doubly magic 2878Ni50 provide essential information on the shell evolution and shape coexistence near the Z=28 and N=50 double shell closure. We report the excitation energy measurement of the 1/2+ isomer in 3079Zn49 through independent high-precision mass measurements with the JYFLTRAP double Penning trap and with the ISOLTRAP multi-reflection time-of-flight mass spectrometer. We unambiguously place the 1/2+ isomer at 942(10) keV, slightly below the 5/2+ state at 983(3) keV. With the use of state-of-the-art shell-model diagonalizations, complemented with discrete nonorthogonal shell-model calculations which are used here for the first time to interpret shape coexistence, we find low-lying deformed intruder states, similar to other N=49 isotones. The 1/2+ isomer is interpreted as the bandhead of a low-lying deformed structure akin to a predicted low-lying deformed band in 80Zn, and points to shape coexistence in 79,80Zn similar to the one observed in 78Ni. The results make a strong case for confirming the claim of shape coexistence in this key region of the nuclear chart.
