Systematic calculations of electric dipole response with fully self-consistent Skyrme-RPA

University of Aizu-JUSTIPEN-EFES Symposium on"Cutting-Edge Physics of Unstable Nuclei"

Univ. of Aizu, November 10-13, 2010

INAKURA Tsunenori (RIKEN)NAKATSUKASA Takashi (RIKEN)

YABANA Kazuhiro (Tsukuba)

Pygmy Dipole Resonance (PDR)

• Candidates for “soft dipole mode.”• Strong impact on r-process.• Nature of PDR is not well-known.

collective or single-particle excitation? What is the condition for its emergence?

P. Adrich et al., PRL 95, 132501.

PRC73, 044325 PRC76, 051603(R)

Precursive studies: PDR correlation with other quantities

Skyrme-RPA in 3D meshT. Inakura et al., PRC80, 044301.

• Fully self-consistent Skyrme-RPA• Including time-odd, residual LS and Coulomb.

• 3D mesh representation• suitable to describe unstable nuclei.• applicable for deformed nuclei.• treat continuum in good approximation.

• No pairing correlation　

Technically…• Finite Amplitude Method numerical estimation of residual interaction..• Response calculation• at fixed complex energies.• suitable for the paralleled supercomputer.

208Pb

Systematic calc. of E1 mode• SkM* interaction.• 3D mesh.• Rbox= 15 fm.• No pairing.

39 spherical nuclei153 prolate nuclei54 oblate nuclei51 triaxial nuclei

-------------------------297 nuclei

Extraction of PDR distribution

PDR distribution

Deformed

PDR - diff. of Rrms, Sn, & N-Z asym. -

Integration up to 10 MeV

Lorentzian fitting

PRC73, 044325.

PDR and diff. of Rrms

Integration up to 10 MeV

Lorentzian fitting

A. Klimkiewicz et al., PRC76, 051603(R)

N-Z asymmetry

PDR: collective?

60CaSkM*Rbox= 25fmG = 0.5 MeV

Collective PDR

SkM* interactionRbox = 25 fm

PDR in 132SnE = 8.2 + 0.5 i MeVRbox = 25 fmSkM* interactionSn = 8.4 MeVRrms = 4.9 fm

Summary

• PDR in light neutron-rich nuclei is mainly neutron emission mode from loosely-bound low-l orbit.• Correlations with N-Z asymmetry and Sn are present.• Strong correlations with Rn-Rp when the PDR grows up.• PDR in light nuclei are single-particle excitations to continuum in RPA scheme.• PDR in some heavy nuclei have collectivity.