Speaker
Dr
Kenichi Yoshida
(Department of Physics, Kyoto University and Institut de Physique Nucleaire, Universite Paris Sud)
Description
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 $\nu(2s^{-1}_{1/2} 2p_{3/2})$ transition dominantly,
and the other mostly by a $\nu(2s^{-1}_{1/2} 2p_{1/2})$ 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.
Primary author
Dr
Kenichi Yoshida
(Department of Physics, Kyoto University and Institut de Physique Nucleaire, Universite Paris Sud)
Co-author
Prof.
Nguyen Van Giai
(Institut de Physique Nucleaire, IN2P3-CNRS)
