Evolution of nuclear structure in neutron-rich odd-Zn isotopes and isomers

Abstract

Collinear laser spectroscopy was performed on Zn ( Z = 30 ) isotopes at ISOLDE, CERN. The study of hyperfine spectra of nuclei across the Zn isotopic chain, N = 33 – 49 , allowed the measurement of nuclear spins for the ground and isomeric states in odd- A neutron-rich nuclei up to N = 50 . Exactly one long-lived (>10 ms) isomeric state has been established in each 69 – 79 Zn isotope. The nuclear magnetic dipole moments and spectroscopic quadrupole moments are well reproduced by large-scale shell–model calculations in the f 5 pg 9 and fpg 9 d 5 model spaces, thus establishing the dominant term in their wave function. The magnetic moment of the intruder I π = 1 / 2 + isomer in 79 Zn is reproduced only if the ν s 1 / 2 orbital is added to the valence space, as realized in the recently developed PFSDG-U interaction. The spin and moments of the low-lying isomeric state in 73 Zn suggest a strong onset of deformation at N = 43 , while the progression towards 79 Zn points to the stability of the Z = 28 and N = 50 shell gaps, supporting the magicity of 78 Ni.