Octupole correlations in positive-parity states of rare-earth and actinide nuclei

¹ Institut für Kernphysik, Universität zu Köln, D-50937 Köln, Germany
² Horia Hulubei National Institute of Physics and Nuclear Engineering, Bucharest, Romania
³ Physik Department, Technische Universität München, München, Germany
⁴ Fakultät für Physik, Ludwig-Maximilians Universität München, München, Germany

^a e-mail: spieker@ikp.uni-koeln.de

Published online: 28 May 2015

Abstract

In this contribution, further evidence of the importance of multiphonon-octupole excitations to describe experimental data in the rare earths and actinides will be presented. First, new results of a (p, t) experiment at the Q3D magnetic spectrograph in Munich will be discussed, which was performed to selectively excite J^π = 0⁺ states in ²⁴⁰Pu. spdf interacting boson model (IBM) calculations suggest that the previously proposed double-octupole phonon nature of the J^π = 0⁺₂ state is not in conflict with its strong (p, t) population. Second, the framework of the IBM has been adopted for the description of experimental observables related to octupole excitations in the rare earths. Here, the IBM is able to describe the signature splitting for positiveand negative-parity states when multi-dipole and multi-octupole bosons are included. The present study might support the idea of octupole-phonon condensation at intermediate spin (J^π = 10⁺) leading to the change in yrast structure observed in ¹⁴⁶Nd.