Quadrupole collectivity in neutron-rich Cd isotopes

¹ Institut für Kernphysik, Technische Universität Darmstadt, Darmstadt, Germany
² INRNE, Bulgarian Academy of Sciences, Sofia, Bulgaria
³ Institut für Kernphysik, Universität zu Köln, Köln, Germany
⁴ Horia Hulubei National Institute for Physics and Nuclear Engineering, Bucharest, Romania
⁵ Instituut voor Kern- en Stralingsfysica, KU Leuven, Leuven, Belgium
⁶ Belgian Nuclear Research Centre SCK CEN, Mol, Belgium
⁷ CERN, Geneva, Switzerland
⁸ Technische Universität München, München, Germany
⁹ Faculty of Physics, University of Warsaw, Warsaw, Poland
¹⁰ Instituto de Estructura de la Materia, Consejo Superior de Investigaciones Científicas, Madrid, Spain
¹¹ Fakultät für Physik, Ludwig-Maximilians-Universität, München, Germany
¹² Faculty of Physics, St.Kliment Ohridski University of Sofia, Sofia, Bulgaria
¹³ Laboratoire de Physique Subatomique et de Cosmologie, Grenoble, France
¹⁴ Department of Physics, University of York, York, United Kingdom

^a e-mail: sboenig@ikp.tu-darmstadt.de

Published online: 20 March 2014

Abstract

The investigation of the excitation energies of the 2₁⁺ –states in the neutron-rich Cd isotopes shows an irregular behaviour when approaching the neutron shell-closure at N = 82. The energy of the 2₁⁺–state in ¹²⁸Cd is lower than the one in ¹²⁶Cd. The transition strength B(E2, 0_gs⁺ → 2₁⁺) in the even isotopes ^122−128Cd was measured in Coulomb excitation experiments with the high-purity germanium detector array MINIBALL at REXISOLDE (CERN). The values for ^122,124Cd coincide with beyond-mean-field calculations with a resultant prolate deformation, whereas ^126,128Cd are better described by shell-model calculations.