Probing Surface Quantum Flows in Deformed Pygmy Dipole Modes

Abstract

In order to explore the nature of collective modes in weakly bound nuclei, we have investigated deformation effects and surface flow patterns of isovector dipole modes in a shape-coexisting nucleus ${}^{40}$Mg. The calculations were done in a fully self-consistent continuum finite-amplitude Quasiparticle Random Phase Approximation (QRPA) in a large deformed spatial mesh. An unexpected result of pygmy and giant dipole modes having disproportionate deformation splittings in strength functions was obtained. Furthermore, the transition current densities demonstrate that the long-sought core-halo oscillation in pygmy resonances is collective and compressional, corresponding to the lowest excitation energy and the simplest quantum flow topology. Our calculations show that surface flow patterns become more complicated as excitation energies increase.

5 pages, 4 figures, accepted for Phys.Rev.C (Rapid Comm.)

References in corpus (11)

• Exotic modes of excitation in atomic nuclei far from stability
• Finite amplitude method for the quasi-particle-random-phase approximation
• Relativistic RPA in axial symmetry
• Deformed Coordinate-Space Hartree-Fock-Bogoliubov Approach to Weakly Bound Nuclei and Large Deformations
• Microscopic calculation and LDA of the spatial dependence of the pairing field with bare and induced interactions
• Finite Amplitude Method for Charge-Changing Transitions in Axially-Deformed Nuclei
• Decay Pattern of Pygmy States Observed in Neutron-Rich 26 Ne
• Continuum Hartree-Fock-Bogoliubov theory for weakly bound deformed nuclei using coordinate-space Green's function method
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• Pygmy dipole mode in deformed neutron-rich Mg isotopes close to the drip line
• Correlation between elliptic flow and shear viscosity in intermediate-energy heavy-ion collisions

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