Shape staggering of midshell mercury isotopes from in-source laser spectroscopy compared with density-functional-theory and Monte Carlo shell-model calculations

Research output: Contribution to journalArticle


  • Simon Sels
  • Thomas Day Goodacre
  • Bruce A Marsh
  • Alessandro Pastore
  • W. Ryssens
  • Yusuke Tsunoda
  • Numa A. Althubiti
  • B. Andel
  • Andrei N. Andreyev
  • Dimitar Atanasov
  • A. E. Barzakh
  • Michael Bender
  • Johathan Billowes
  • Klaus Blaum
  • Thomas Elias Cocolios
  • Cubiss James G.
  • Jacek Dobaczewski
  • Gregory James Farooq-Smith
  • Dmitry V. Fedorov
  • Valentin N. Fedosseev
  • Kieran T. Flanagan
  • Liam Paul Gaffney
  • Paul-Henri Heenen

Institutes & Expert groups

  • University of York
  • Tokyo University
  • Comenius University Bratislava
  • IPNL - Institut de Physique Nucléaire de Lyon
  • University of Manchester
  • ULB - Université Libre de Bruxelles
  • KUL - Katholieke Universiteit Leuven
  • CERN - Conseil Européen pour la Recherche Nucléaire
  • ASRC - Advanced Science Research Center - JAEA
  • IPP - Max-Planck-Institut für Plasmaphysik
  • PNPI - Petersburg Nuclear Physics Institute
  • NRCKI - National research Center Kurchatov Institute
  • University of Liverpool

Documents & links


Neutron-deficient 177−185Hg isotopes were studied using in-source laser resonance-ionization spectroscopy at the CERN-ISOLDE radioactive ion-beam facility in an experiment combining different detection methods tailored to the studied isotopes. These include either α-decay tagging or multireflection time-of-flight gating for isotope identification. The endpoint of the odd-even nuclear shape staggering in mercury was observed directly by measuring for the first time the isotope shifts and hyperfine structures of 177−180Hg. Changes in the meansquare charge radii for all mentioned isotopes, magnetic dipole, and electric quadrupole moments of the odd-A isotopes and arguments in favor of I = 7/2 spin assignment for 177,179Hg were deduced. Experimental results are compared with density functional theory (DFT) and Monte Carlo shell model (MCSM) calculations. DFT calculations using Skyrme parametrizations predict a jump in the charge radius around the neutron N = 104 midshell, with an odd-even staggering pattern related to the coexistence of nearly degenerate oblate and prolate minima. This near-degeneracy is highly sensitive to many aspects of the effective interaction, a fact that renders perfect agreement with experiments out of reach for current functionals. Despite this inherent difficulty, the SLy5s1 and a modified UNEDF1SO parametrization predict a qualitatively correct staggering that is off by two neutron numbers. MCSM calculations of states with the experimental spins and parities show good agreement for both electromagnetic moments and the observed charge radii. A clear mechanism for the origin of shape staggering within this context is identified: a substantial change in occupancy of the proton πh9/2 and neutron νi13/2 orbitals.


Original languageEnglish
Article number044306
Pages (from-to)1-17
Number of pages17
JournalPhysical Review C
Publication statusPublished - 12 Apr 2019


  • ISOLDE, laser spectroscopy, shell model, mercury

ID: 5102270