Abstract

Systematic theoretical investigations of dipole response in neutron-rich nuclei of importance for day-one photonuclear experiments at ELI-NP are presented. The calculations are performed in advanced mi- croscopic theory based on energy-density functional and three-phonon quasiparticle-phonon model. The model basis accounts for a large range of nuclear excitations with different spin and parity. In the focus of the studies are electric and magnetic dipole modes with energies up to 25 MeV. Of special interest are pygmy dipole and giant dipole resonances. The impact of different low-energy excitations and in particular of the PDR on radia- tive neutron-capture reaction cross sections in nuclei of key importance for nucleosynthesis is investigated.The obtained results are compared to available experimental data.

Highlights

  • New aspects of nuclear dynamics below and around the neutron threshold in nuclei with small and moderate neutron excess has been explored in our studies of low-energy electric and magnetic dipole and quadrupole excitations [1]

  • New modes of nuclear excitation closely connected with the skin phenomena in atomic nuclei- the pygmy dipole resonance (PDR) [5,6,7,8,9,10,11,12] and its natural extension at higher multipolarities - the pygmy quadrupole resonance (PQR) [13,14,15] have been observed and investigated

  • The first one is related to the mean field and the pure PDR associated with neutron skin oscillations, while the second one represents the coupling of the single-particle states with a more complex excitations related to core polarization and giant dipole resonance (GDR)

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Summary

Introduction

New aspects of nuclear dynamics below and around the neutron threshold in nuclei with small and moderate neutron excess has been explored in our studies of low-energy electric and magnetic dipole and quadrupole excitations [1]. The first one is related to the mean field and the pure PDR associated with neutron skin oscillations, while the second one represents the coupling of the single-particle states with a more complex excitations related to core polarization and giant dipole resonance (GDR). These effects lead to the redistribution and fragmentation of the lowenergy dipole strength. EDF+three-phonon QPM results on the fine and gross spectral features of E1 and M1 excitations up to GDR energies are presented and compared to experimental data [4]

The theoretical approach
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