Low-lying dipole resonance in neutron-rich Ne isotopes

K. Yoshida , N. van Giai (1)

1 IPNO - Institut de Physique Nucléaire d'Orsay

Microscopic structure of the low-lying isovector dipole excitation mode in neutron-rich 26,28,30Ne 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 obtain the low-lying resonance in 26Ne at around 8.6 MeV. It is found that the isovector dipole strength at Ex<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^-12p3/2) transition dominantly and the other mostly by a nu(2s_1/2^-12p1/2) transition. The neutron excitations take place outside of the nuclear surface reflecting the spatially extended structure of the 2s1/2 wave function. In 30Ne, the deformation splitting of the giant resonance is large, and the low-lying resonance overlaps with the giant resonance.

Domaines: Physique Nucléaire Théorique [nucl-th]

K. Yoshida, N. van Giai. Low-lying dipole resonance in neutron-rich Ne isotopes. Physical Review C, 2008, 78, pp.014305. ⟨10.1103/PhysRevC.78.014305⟩. ⟨in2p3-00421695⟩