Eur. Phys. J. A (2010) 43: 313-321
https://doi.org/10.1140/epja/i2010-10933-y

Regular Article - Theoretical Physics

The low-energy dipole structure of ²³²Th , ²³⁶U and ²³⁸U actinide nuclei

¹ Physics Department, Faculty of Arts and Sciences, Sakarya University, 54100, Serdivan, Adapazari, Turkey
² Institute of Physics, Academy of Sciences, H. Cavid Avenue 33, Baku, Azerbaijan
³ Institut fur Kernphysik, Technische Universitat Darmstadt, Darmstadt, Germany

^* e-mail: ertugral@sakarya.edu.tr

Received: 17 December 2008
Revised: 27 December 2009
Accepted: 7 January 2010
Published online: 5 February 2010

Abstract

In this study, and dipole mode excitations are systematically investigated within the rotational and translational + Galilean invariant quasiparticle random-phase approximation for ²³²Th , ²³⁶U , and ²³⁸U actinide nuclei. It is shown that the investigated nuclei reach a B(M1) strength structure, which corresponds to the scissors mode. The calculated mean excitation energies as well as the summed B(M1) value of the scissors mode excitations are consistent with the available experimental data. The results of calculations indicate large differences to the rare-earth nuclei as is the case for the experiment: a doubling of the observed dipole strengths and a shift of the energy centroid to the lower energies by about 800keV. The calculations indicate the presence of a few prominent negative-parity states in the 2.0-4.0MeV energy interval. The occurrence of the negative-parity dipole states with the rather high B(E1) value less than 4MeV shows the necessity of explicit parity measurements for the correct determination of the scissors mode strength in ²³²Th , ²³⁶U , and ²³⁸U isotopes.