Eur. Phys. J. A (2019) 55: 130
https://doi.org/10.1140/epja/i2019-12815-2

Regular Article - Experimental Physics

Electromagnetic properties of low-lying states in neutron-deficient Hg isotopes: Coulomb excitation of ¹⁸²Hg, ¹⁸⁴Hg, ¹⁸⁶Hg and ¹⁸⁸Hg

¹ Heavy Ion Laboratory, University of Warsaw, PL-02-093, Warsaw, Poland
² Instituut voor Kern- en Stralingsfysica, KU Leuven, BE-3001, Leuven, Belgium
³ Université de Strasbourg, CNRS, IPHC UMR7178, F-67000, Strasbourg, France
⁴ IRFU CEA, Université Paris-Saclay, F-91191, Gif-sur-Yvette, France
⁵ Oliver Lodge Laboratory, University of Liverpool, L69 7ZE, Liverpool, UK
⁶ ISOLDE, CERN, CH-1211, Geneva 23, Switzerland
⁷ School of Engineering, Computing and Physical Sciences, University of the West of Scotland, PA1 2BE, Paisley, UK
⁸ Department of Physics, University of York, YO10 5DD, York, UK
⁹ GANIL CEA/DSM-CNRS/IN2P3, Boulevard H. Becquerel, F-14076, Caen, France
¹⁰ IPNL, Université de Lyon, Université Lyon 1, CNRS/IN2P3, F-69622, Villeurbanne Cedex, France
¹¹ Institut für Kernphysik, Universität zu Köln, DE-50937, Köln, Germany
¹² Physics Division, Argonne National Laboratory, 60439, Argonne, Illinois, USA
¹³ Physics Department, University of Lund, Box 118, SE-221 00, Lund, Sweden
¹⁴ School of Physics and Astronomy, University of Manchester, M13 9PL, Manchester, UK
¹⁵ Belgian Nuclear Research Centre SCK CEN, B-2400, Mol, Belgium
¹⁶ Grupo de Física Nuclear, Universidad Complutense de Madrid, 28040, Madrid, Spain
¹⁷ Departamento de Ciencias Integradas y Centro de Estudios Avanzados en Fısica, Matemáticas y Computación, Universidad de Huelva, 21071, Huelva, Spain
¹⁸ Physics Department E12, Technische Universität München, D-85748, Garching, Germany
¹⁹ University of Jyväskylä, Department of Physics, P.O. Box 35, FI-40014, Jyvaskyla, Finland
²⁰ Helsinki Institute of Physics, University of Helsinki, P.O. Box 64, FIN-00014, Helsinki, Finland
²¹ Department of Physics, University of Oslo, N-0316, Oslo, Norway
²² Department of Physics, University of Guelph, N1G 2W1, Guelph, Ontario, Canada
²³ Department of Particle Physics, Weizmann Institute of Science, 76100, Rehovot, Israel
²⁴ Physique Nucléaire Théorique, Université Libre de Bruxelles, B-1050, Bruxelles, Belgium
²⁵ Department of Physics and Astronomy, Ghent University, B-9000, Gent, Belgium
²⁶ Institut für Kernphysik, Technische Universität Darmstadt, D-64289, Darmstadt, Germany
²⁷ Department of Physics, Ludwig Maximilian Universität München, 85748, Garching, Germany
²⁸ Department of Physics, The University of Ioannina, GR-45110, Ioannina, Greece
²⁹ Paul Scherrer Institut, 5232, Villigen PSI, Switzerland
³⁰ National Physical Laboratory, Hampton Road, TW11 0LW, Teddington, UK
³¹ School of Physics, Georgia Institute of Technology, 30332-0430, Atlanta, Georgia, USA

^* e-mail: wrzosek@slcj.uw.edu.pl

Received: 27 February 2019
Accepted: 28 June 2019
Published online: 22 August 2019

Abstract

The neutron-deficient mercury isotopes serve as a classical example of shape coexistence, whereby at low energy near-degenerate nuclear states characterized by different shapes appear. The electromagnetic structure of even-mass ^182-188 Hg isotopes was studied using safe-energy Coulomb excitation of neutron-deficient mercury beams delivered by the REX-ISOLDE facility at CERN. The population of , and states was observed in all nuclei under study. Reduced E2 matrix elements coupling populated yrast and non-yrast states were extracted, including their relative signs. These are a sensitive probe of shape coexistence and may be used to validate nuclear models. The experimental results are discussed in terms of mixing of two different configurations and are compared with three different model calculations: the Beyond Mean Field model, the Interacting Boson Model with configuration mixing and the General Bohr Hamiltonian. Partial agreement with experiment was observed, hinting to missing ingredients in the theoretical descriptions.