Isoscalar and Isovector Splitting of Pygmy Dipole Structures

Paar, Nils and Niu, Y. F. and Vretenar, Dario and Meng, Jie (2009) Isoscalar and Isovector Splitting of Pygmy Dipole Structures. Physical Review Letters, 103 (3). pp. 32502-4. ISSN 0031-9007

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The electric dipole response of 140Ce is investigated using the fully consistent relativistic quasiparticle random phase approximation. By analyzing the isospin structure of the E1 response, it is shown that the low-energy (pygmy) strength separates into two segments with different isospin character. The more pronounced pygmy structure at lower energy is composed of predominantly isoscalar states with surface-peaked transition densities. At somewhat higher energy the calculated E1 strength is primarily of isovector character, as expected for the low-energy tail of the giant dipole resonance. The results are in qualitative agreement with those obtained in recent (gamma, gamma') and (alpha, alpha'gamma) experiments, and provide a simple explanation for the splitting of low-energy E1 strength into two groups of states with different isospin structure and radial dependence of the corresponding transition densities.

Item Type: Article
Keywords: nuclear physics, collective excitations, exotic nuclei
Date: July 2009
Subjects: NATURAL SCIENCES > Physics > Nuclear Physics
Additional Information: Copyright (2009) by the American Physical Society.
Divisions: Faculty of Science > Department of Physics
Project code: 119-1191005-1010, UKF 17/08
Publisher: American Physical Society
Depositing User: Gordana Stubičan Ladešić
Date Deposited: 30 May 2014 16:33
Last Modified: 01 Jun 2014 07:54

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