Relativistic quasiparticle time blocking approximation: Dipole response of open-shell nuclei

Journal Article · Tue Jul 15 04:00:00 EDT 2008 · Physical Review. C, Nuclear Physics

DOI:https://doi.org/10.1103/PHYSREVC.78.014312· OSTI ID:21192029

Litvinova, E; Ring, P; Tselyaev, V ^[1]

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1. Gesellschaft fuer Schwerionenforschung mbH, Planckstrasse 1, D-64291 Darmstadt, Germany and Institute of Physics and Power Engineering, RU-249033 Obninsk (Russian Federation)

The self-consistent relativistic quasiparticle random-phase approximation (RQRPA) is extended by the quasiparticle-phonon coupling (QPC) model using the quasiparticle time blocking approximation (QTBA). The method is formulated in terms of the Bethe-Salpeter equation (BSE) in the two-quasiparticle space with an energy-dependent two-quasiparticle residual interaction. This equation is solved either in the basis of Dirac states forming the self-consistent solution of the ground state or in the momentum representation. Pairing correlations are treated within the Bardeen-Cooper-Schrieffer (BCS) model with a monopole-monopole interaction. The same NL3 set of the coupling constants generates the Dirac-Hartree-BCS single-quasiparticle spectrum, the static part of the residual two-quasiparticle interaction and the quasiparticle-phonon coupling amplitudes. A quantitative description of electric dipole excitations in the chain of tin isotopes (Z=50) with the mass numbers A=100,106,114,116,120, and 130 and in the chain of isotones with (N=50) {sup 88}Sr, {sup 90}Zr, {sup 92}Mo is performed within this framework. The RQRPA extended by the coupling to collective vibrations generates spectra with a multitude of 2q x phonon (two quasiparticles plus phonon) states providing a noticeable fragmentation of the giant dipole resonance as well as of the soft dipole mode (pygmy resonance) in the nuclei under investigation. The results obtained for the photo absorption cross sections and for the integrated contributions of the low-lying strength to the calculated dipole spectra agree very well with the available experimental data.

• OSTI ID: 21192029
• Journal Information: Physical Review. C, Nuclear Physics, Journal Name: Physical Review. C, Nuclear Physics Journal Issue: 1 Vol. 78; ISSN 0556-2813; ISSN PRVCAN
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ABSORPTION
ATOMIC NUMBER
BCS THEORY
BETHE-SALPETER EQUATION
CHANNELING
CORRELATIONS
COUPLING
COUPLING CONSTANTS
CROSS SECTIONS
ELECTRIC DIPOLES
ENERGY DEPENDENCE
EXCITATION
FRAGMENTATION
GROUND STATES
ISOTONIC NUCLEI
MASS
MATHEMATICAL SOLUTIONS
MOLYBDENUM 92
MONOPOLES
PAIRING INTERACTIONS
PHONONS
RANDOM PHASE APPROXIMATION
RELATIVISTIC RANGE
RESIDUAL INTERACTIONS
RESONANCE
SPECTRA
STRONTIUM 88
TIN ISOTOPES
ZIRCONIUM 90