Probing the neutron skin thickness in collective modes of excitation

Abstract

Nuclear collective motion provides valuable constraint on the size of neutron-skin thickness and the properties of nuclear matter symmetry energy. By employing relativistic nuclear energy density functional (RNEDF) and covariance analysis related to ${\chi }^2$ fitting of the model parameters, relevant observables are identified for dipole excitations, which strongly correlate with the neutron-skin thickness $(r_{np})$, symmetry energy at saturation density $(J)$ and slope of the symmetry energy $(L)$. Using the RNEDF framework and experimental data on pygmy dipole strength (${}^{68}$Ni, ${}^{132}$Sn, ${}^{208}$Pb) and dipole polarizability (${}^{208}$Pb), it is shown how the values of $J$, and $L$, and $r_{np}$ are constrained. The isotopic dependence of moments associated to dipole excitations in ${}^{116-136}$Sn shows that the low-energy dipole strength and polarizability in neutron-rich nuclei display strong sensitivity to the symmetry energy parameter $J$, more pronounced than in isotopes with moderate neutron-to-proton number ratios.

8 pages, 7 figures, to appear in the INPC2013 conference proceedings, European Physical Journal Web of Conferences

References in corpus (7)

• Exotic modes of excitation in atomic nuclei far from stability
• Neutron skin of 208Pb, nuclear symmetry energy, and the parity radius experiment
• Constraints on the symmetry energy and on neutron skins from the pygmy resonances in 68Ni and 132Sn
• Electric Dipole Polarizability in ${}^{208}$Pb: insights from the Droplet Model
• Pygmy dipole resonance as a constraint on the neutron skin of heavy nuclei
• Giant Quadrupole Resonances in 208Pb, the nuclear symmetry energy and the neutron skin thickness
• Pygmy Resonances and Neutron Skins

Cited by in corpus (1)

• Nuclear Equation of State from ground and collective excited state properties of nuclei