Charge Radii of Zn and Ni Isotopes Measured by Collinear Laser Spectroscopy

The hyperne structures and isotopes shifts have been measured for isotope chains of zinc (Z=30) and nickel (Z=28) using collinear laser spectroscopy on atom beams provided by the on-line isotope separator facility, ISOLDE, at CERN. The isotopes 62-80Zn were measured on the 481 nm transition from a metastable 3P2 state at 32,890.35 cm-1 to a 3S1 state at 53,672.28 cm-1. One isomer was also observed for each of the odd isotopes 69-79Zn. The ground states of 58-68;70Ni where measured on the 352 nm transition from a metastable 3D3 state at 204.79 cm-1 to a 3P2 state at 28,569.20 cm-1. The mean square charge radii of these Zn and Ni isotopes were deduced using atomic factors extracted from King plots. The results, together with previous data of Cu (Z=29) and Ga (Z=31), depict the evolution of the debated N=40 sub-shell as the proton number moves away from the Z=28 closed shell. Eects of the proton occupation number of orbitals above Z=28 and nuclear deformation were also explored on the Zn isotopes showing the charge radii of nuclei are determined by various factors in a complicated combination.