Structure and decay of the pygmy dipole resonance in 26Ne

TL;DR

This study uses advanced nuclear models to analyze the structure and decay of the pygmy dipole resonance in neutron-rich neon isotopes, revealing neutron excitation dominance and core coupling effects.

Contribution

It provides a detailed theoretical analysis of PDR in 26Ne using AMD methods, highlighting the role of neutron excitation and core coupling, which advances understanding of nuclear structure in neutron-rich isotopes.

Findings

PDR energy and strength agree with experimental data.

PDR is dominated by neutron excitation coupled to the core.

Large isoscalar component and enhanced core excitation are observed.

Abstract

The low-lying spectra of $^{24,25,26}{\rm Ne}$ and the structure of the pygmy dipole resonance (PDR) in $^{26}{\rm Ne}$ have been theoretically studied by the antisymmetrized molecular dynamics (AMD) and its extended version called shifted-basis AMD. The calculated energy and strength of the PDR reasonably agree with the observation, and the analysis of the wave function shows that the PDR is dominated by neutron excitation coupled to the quadrupole excited core nucleus $^{25}{\rm Ne}$, which explains the observed unexpected decay of PDR to the excited states of $^{25}{\rm Ne}$. The large isoscalar component of PDR is also shown and the enhancement of the core excitation in neutron-rich Ne isotopes is conjectured.