Studies of pear-shaped nuclei using accelerated radioactive beams

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  • Liam Paul Gaffney
  • Peter A Butler
  • Marcus Scheck
  • Adam B Hayes
  • Frederik Wenander
  • Michael Albers
  • Beyhan Bastin
  • Christopher Bauer
  • Andrey Blazhev
  • Sabine Bönig
  • Nick Bree
  • Joachim Cederkäll
  • T Chupp
  • Douglas Cline
  • Thomas Elias Cocolios
  • T Davinson
  • Hilde De Witte
  • Jan Diriken
  • Tuomas Grahn
  • A Herzan
  • Mark Huyse
  • David G Jenkins
  • David T Joss
  • Joonas Konki
  • M Kowalczyk
  • Thorsten Kröll
  • E Kwan
  • Rudi Lutter
  • Kevin Moschner
  • Pawel Napiorkowski
  • Janne Pakarinen
  • M Pfeiffer
  • D Radeck
  • Peter Reiter
  • Karel Reynders
  • SV Rigby
  • LM Robledo
  • M Rudigier
  • Sara Sambi
  • Michael Seidlitz
  • Burkhard Siebeck
  • Thierry Stora
  • P Thoele
  • Piet Van Duppen
  • MJ Vermeulen
  • Mirko von Schmid
  • Didier Voulot
  • Nigel Warr
  • Kathrin Wimmer
  • Kasia Wrzosek-Lipska
  • CY Wu
  • Magda Zielinska

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There is strong circumstantial evidence that certain heavy, unstable atomic nuclei are ‘octupole deformed’, that is, distorted into a pear shape. This contrasts with the more prevalent rugby-ball shape of nuclei with reflectionsymmetric, quadrupole deformations. The elusive octupole deformed nuclei are of importance for nuclear structure theory, and also in searches for physics beyond the standard model; any measurable electric-dipole moment (a signature of the latter) is expected to be amplified in such nuclei. Here we determine electric octupole transition strengths (a direct measure of octupole correlations) for short-lived isotopes of radon and radium. Coulomb excitation experiments were performed using accelerated beams of heavy, radioactive ions. Our data on 220Rn and 224Ra show clear evidence for stronger octupole deformation in the latter. The results enable discrimination between differing theoretical approaches to octupole correlations, and help to constrain suitable candidates for experimental studies of atomic electric-dipole moments that might reveal extensions to the standard model.


Original languageEnglish
Pages (from-to)199-204
Issue number7448
Publication statusPublished - 9 May 2013


  • Coulomb excitation, octupole, pear shape, REX Isolde, radium, radon

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