6533b858fe1ef96bd12b614e

RESEARCH PRODUCT

Experimental determination of anIπ=2−ground state inCu72,74

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This article reports on the ground-state spin and moments measured in $^{72,74}\mathrm{Cu}$ using collinear laser spectroscopy at the CERN On-Line Isotope Mass Separator (ISOLDE) facility. From the measured hyperfine coefficients, the nuclear observables $\ensuremath{\mu}$(${}^{72}\mathrm{Cu})=\ensuremath{-}1.3472(10){\ensuremath{\mu}}_{N}$, $\ensuremath{\mu}({}^{74}\mathrm{Cu})=\ensuremath{-}1.068(3){\ensuremath{\mu}}_{N}$, $Q({}^{72}\mathrm{Cu})=+8(2) {\mathrm{efm}}^{2}$, $Q({}^{74}\mathrm{Cu})=+26(3) {\mathrm{efm}}^{2}$, $I({}^{72}\mathrm{Cu})=2$, and $I({}^{74}\mathrm{Cu})=2$ have been determined. Through a comparison of the measured magnetic moments with different models, the negative moment reveals a strong $\ensuremath{\pi}{f}_{5/2}\ensuremath{\bigotimes}\ensuremath{\nu}{g}_{9/2}$ component in the ground-state wave function. Consequently, a negative parity has been assigned to the ground states of $^{72,74}\mathrm{Cu}$. Large-scale shell-model calculations illustrate the strong sensitivity of the nuclear moments to configuration mixing and to the effective interaction employed.