Eur. Phys. J. A (2013) 49: 119
https://doi.org/10.1140/epja/i2013-13119-3

Regular Article - Theoretical Physics

Toroidal, compression, and vortical dipole strengths in ^144-154Sm: Skyrme-RPA exploration of the deformation effect

¹ Institute of Particle and Nuclear Physics, Charles University, CZ-18000, Praha 8, Czech Republic
² Laboratory of Theoretical Physics, Joint Institute for Nuclear Research, 141980, Moscow region, Russia
³ Technische Universität Dresden, Inst. für Analysis, D-01062, Dresden, Germany
⁴ Institut für Theoretische Physik II, Universität Erlangen, D-91058, Erlangen, Germany
⁵ Dipartimento di Scienze Fisiche, Università di Napoli Federico II, Via Cintia, I-80126, Napoli, Italy
⁶ Istituto Nazionale di Fisica Nucleare, Via Cintia, I-80126, Napoli, Italy

Received: 29 May 2013
Accepted: 3 September 2013
Published online: 23 September 2013

Abstract

A comparative analysis of toroidal, compressional and vortical dipole strengths in the spherical ¹⁴⁴Sm and the deformed ¹⁵⁴Sm is performed within the random-phase approximation using a set of different Skyrme forces. Isoscalar (T = 0, isovector (T = 1 , and electromagnetic excitation channels are considered. The role of the nuclear convection and magnetization currents is inspected. It is shown that the deformation leads to an appreciable redistribution of the strengths and causes a spectacular deformation splitting (exceeding 5MeV) of the isoscalar compressional mode. When stepping from ¹⁴⁴Sm to ¹⁵⁴Sm, we observe an increase of the toroidal, compression and vortical contributions in the low-energy region (often called pygmy resonance). The strength in this region seems to be an overlap of various excitation modes. The energy centroids of the strengths depend significantly on the isoscalar effective mass m₀. Skyrme forces with a large m₀ (typically seem to be more suitable for the description of experimental data for the isoscalar giant dipole resonance.