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

• Published in: arXiv.org 2016-04
• Main Authors: Yang, X F, Wraith, C, Xie, L, Babcock, C, Billowes, J, Bissell, M L, Blaum, K, Cheal, B, Flanagan, K T, Garcia Ruiz, R F, Gins, W, Gorges, C, Grob, L K, Heylen, H, Kaufmann, S, Kowalska, M, Kraemer, J, Malbrunot-Ettenauer, S, Neugart, R, Neyens, G, Nörtershäuser, W, Papuga, J, Sánchez, R, Yordanov, D T
• Format: Article
• Language: English
• Subjects: Hyperfine structure; Magnetic fields; Magnetic moments; Mossbauer spectroscopy; Parity
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.1604.03316

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.