Low-lying dipole resonance in neutron-rich Ne isotopes

Abstract

Microscopic structure of the low-lying isovector dipole excitation mode in neutron-rich ${}^{26,28,30}$Ne is investigated by performing deformed quasiparticle-random-phase-approximation (QRPA) calculations. The particle-hole residual interaction is derived from a Skyrme force through a Landau-Migdal approximation. We have obtained the low-lying resonance in ${}^{26}$Ne at around 8.5 MeV. It is found that the isovector dipole strength at $E_x<10$ MeV exhausts about 6.0% of the classical Thomas-Reiche-Kuhn dipole sum rule. This excitation mode is composed of several QRPA eigenmodes, one is generated by a $\nu (2s_{1/2}^{-1}2p_{3/2})$ transition dominantly, and the other mostly by a $\nu (2s_{1/2}^{-1}2p_{1/2})$ transition. The neutron excitations take place outside of the nuclear surface reflecting the spatially extended structure of the $2s_{1/2}$ wave function. In ${}^{30}$Ne, the deformation splitting of the giant resonance is large, and the low-lying resonance is overlapping with the giant resonance.

8 pages, 9 figures and 5 tables

References in corpus (5)

• Self-consistent description of multipole strength: systematic calculations
• Relativistic RPA plus phonon-coupling analysis of pygmy dipole resonances
• Pairing and continuum effects on low-frequency quadrupole vibrations in deformed Mg isotopes close to the neutron drip line
• Low-frequency $K^{\pi }=0^{+}$ modes in deformed neutron-rich nuclei: Pairing- and $\beta$-vibrational modes of neutron
• Search for low lying dipole strength in the neutron rich nucleus ${}^{26}$Ne

Cited by in corpus (2)

• Low-energy dipole excitations in neon isotopes and N=16 isotones within the quasiparticle random phase approximation and the Gogny force
• Pygmy dipole mode in deformed neutron-rich Mg isotopes close to the drip line