Eur. Phys. J. A (2015) 51: 23
https://doi.org/10.1140/epja/i2015-15023-2

Regular Article - Experimental Physics

Direct observation of an isomeric state in ⁹⁸Rb and nuclear properties of exotic rubidium isotopes measured by laser spectroscopy

¹ TRIUMF, V6T 2A3, Vancouver, British Columbia, Canada
² Department of Physics, University of British Columbia, V6T 1Z1, Vancouver, British Columbia, Canada
³ School of Physics and Astronomy, The University of Manchester, M13 9PL, Manchester, UK
⁴ Physics Department, McGill University, H3A 2T8, Montréal, Québec, Canada
⁵ Department of Physics, University of Liverpool, L69 7ZE, Liverpool, UK
⁶ Technische Universität Berlin, 10623, Berlin, Germany
⁷ Department of Physics, University of Jyväskylä, FIN-40014, Jyväskylä, Finland
⁸ Rio Bianco Institute, Ministry of External Relations, 70.170-90, Brasilia, Brazil

^* e-mail: tprocter@triumf.ca

Received: 8 October 2014
Revised: 10 February 2015
Accepted: 18 February 2015
Published online: 27 February 2015

Abstract

Fast-beam collinear laser spectroscopy experiments on rubidium have been performed at the ISAC radioactive ion beam facility at TRIUMF. Most recently, the neutron-rich ⁹⁸Rb isotope has been studied for the investigation of shape coexistence. Two long-lived nuclear states in ⁹⁸Rb have been clearly observed for the first time: a low-spin state, assigned a spin of I = 0, and a high-spin state. The high-spin state is tentatively assigned a spin of I = 3 based on this analysis in combination with gamma decay results. The measured nuclear properties of the two states are presented, alongside unpublished values of the neutron-deficient isotopes investigated previously. The mean-square charge radii of both states in ⁹⁸Rb are observed to continue along the isodeformation line present after the N = 60 onset of deformation.