Eur. Phys. J. A (2017) 53: 50
https://doi.org/10.1140/epja/i2017-12224-7

Regular Article - Experimental Physics

Shell evolution of stable N = 50-56 Zr and Mo nuclei with respect to low-lying octupole excitations

¹ School of Engineering and Computing, University of the West of Scotland, PA1 2BE, Paisley, UK
² SUPA, Scottish Universities Physics Alliance, G12 8QQ, Glasgow, UK
³ Institut für Kernphysik, Technische Universität Darmstadt, D-64289, Darmstadt, Germany

^* e-mail: marcus.scheck@uws.ac.uk

Received: 22 November 2016
Accepted: 1 February 2017
Published online: 15 March 2017

Abstract

For the N = 50-56 zirconium (Z = 40) and molybdenum (Z = 42) isotopes, the evolution of subshells is evaluated by extracting the effective single-particle energies from available particle-transfer data. The extracted systematic evolution of neutron subshells and the systematics of the excitation energy of the octupole phonons provide evidence for type-II shape coexistence in the Zr isotopes. Employing a simplistic approach, the relative effective single-particle energies are used to estimate whether the formation of low-lying octupole-isovector excitations is possible at the proposed energies. The results raise doubts about this assignment.