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Abstract:

This work presents the nuclear spins, magnetic moments, quadrupole momentsand differences in mean square radii of the Cu isotopes 58−75Cu.The collinear laser spectroscopy technique was used. The experimentswere performed at the collinear laser spectroscopy setup COLLAPS atISOLDE, CERN. A detailed overview of the setup and the analysis procedureof laser spectroscopy data is given in this work. A recent technicalimprovement was the installation of the RFQ beam cooler, which allowedto extend the measurements toward more exotic isotopes. The groundstatespin inversion for the odd-A Cu isotopes from spin 3/2 to 5/2 isestablished to occur at 75Cu. This result presents a breakthrough in experimentaland theoretical investigations in this region. The spin-parityof the odd-odd Cu isotopes 72−74Cu is determined to be 2−. The resultingmagnetic moments and quadrupole moments are compared withtheoretical calculations in a f5/2pg9/2 model space and a pf shell modelspace.The magnetic moments of the odd-A Cu isotopes clearly show that excitationsacross the Z = 28 and N = 28 shell gaps need to be includedin the model space to reproduce the experimental trend, providing anotherevidence of the softness of the 56Ni core. The odd-A as well as theodd-odd A Cu isotopes illustrate the sensitivity of the magnetic momentto the detailed composition of the wave function, which makes magneticmoments crucial parameters to evaluate shell model calculations.The quadrupole moments show a minimum in collectivity at N = 40.However, this is not entirely related to the magnitude of the N = 40subshell gap but largely induced by the opposite parity of the g9/2 orbitcompared to the pf shell orbits, which blocks single-particle excitationsacross N = 40. The experimental quadrupole trend does not support anincrease of collectivity beyond N = 40. Theoretical calculations in a pfmodel space appear to underestimate the experimental core polarizationfor the neutron-deficient Cu nuclei.The procedure of extracting the differences in mean square charge radiifrom the measured isotope shifts is given in detail. Comparison of themean square charge radii with the droplet model prediction suggests asignificant collectivity in the Cu isotope chain. A small structural effectat N = 40 is observed.