Isomer shift and magnetic moment of the long-lived 1/2$^{+}$ isomer in $^{79}_{30}$Zn$_{49}$: signature of shape coexistence near $^{78}$Ni

Abstract : Collinear laser spectroscopy has been performed on the $^{79}_{30}$Zn$_{49}$ isotope at ISOLDE-CERN. The existence of a long-lived isomer with a few hundred milliseconds half-life was confirmed, and the nuclear spins and moments of the ground and isomeric states in $^{79}$Zn as well as the isomer shift were measured. From the observed hyperfine structures, spins $I = 9/2$ and $I = 1/2$ are firmly assigned to the ground and isomeric states. The magnetic moment $\mu$ ($^{79}$Zn) = $-$1.1866(10) $\mu_{\rm{N}}$, confirms the spin-parity $9/2^{+}$ with a $\nu g_{9/2}^{-1}$ shell-model configuration, in excellent agreement with the prediction from large scale shell-model theories. The magnetic moment $\mu$ ($^{79m}$Zn) = $-$1.0180(12) $\mu_{\rm{N}}$ supports a positive parity for the isomer, with a wave function dominated by a 2h-1p neutron excitation across the $N = 50$ shell gap. The large isomer shift reveals an increase of the intruder isomer mean square charge radius with respect to that of the ground state: $\delta \langle r^{2}_{c}\rangle^{79,79m}$ = +0.204(6) fm$^{2}$, providing first evidence of shape coexistence.
Type de document :
Pré-publication, Document de travail
5 pages, 4 figures, 1 table, Accepeted by Phys. Rev. Lett. (2016). 2016
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http://hal.in2p3.fr/in2p3-01336062
Contributeur : Sophie Heurteau <>
Soumis le : mercredi 22 juin 2016 - 15:49:41
Dernière modification le : jeudi 11 janvier 2018 - 06:12:41

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  • HAL Id : in2p3-01336062, version 1
  • ARXIV : 1604.03316

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X. F. Yang, C. Wraith, L. Xie, C. Babcock, J. Billowes, et al.. Isomer shift and magnetic moment of the long-lived 1/2$^{+}$ isomer in $^{79}_{30}$Zn$_{49}$: signature of shape coexistence near $^{78}$Ni. 5 pages, 4 figures, 1 table, Accepeted by Phys. Rev. Lett. (2016). 2016. 〈in2p3-01336062〉

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