Anti-analog giant dipole resonances and the neutron skin of nuclei

TL;DR

This paper proposes a method to determine neutron-skin thickness of nuclei using charge-exchange anti-analog giant dipole resonance data, with calculations matching experimental trends and providing constraints on neutron-skin values.

Contribution

It introduces a novel approach combining RQRPA calculations and experimental data to accurately constrain neutron-skin thickness in nuclei.

Findings

Calculations reproduce isotopic trends of AGDR and IVSGDR energies.

The method constrains neutron-skin thickness with high precision.

For 124Sn, neutron-skin thickness is determined as 0.21(5) fm.

Abstract

We examine a method to determine the neutron-skin thickness of nuclei using data on the charge-exchange anti-analog giant dipole resonance (AGDR). Calculations performed using the relativistic proton-neutron quasiparticle random-phase approximation (RQRPA) reproduce the isotopic trend of the excitation energies of the AGDR, as well as that of the spin-flip giant dipole resonances (IVSGDR), in comparison to available data for the even-even isotopes 112-124Sn. It is shown that the excitation energies of the AGDR, obtained using a set of density-dependent effective interactions which span a range of the symmetry energy at saturation density, supplemented with the experimental values, provide a stringent constraint on the value of the neutron-skin thickness. For 124Sn, in particular, we determine the value DRpn=0.21(5) fm. The result of the present study shows that a measurement of the excitation energy of the AGDR in (p,n) reactions using rare-isotope beams in inverse kinematics, provides a valuable method for the determination of the neutron-skin thickness in exotic nuclei.