Effect of symmetry energy on the structure and α-decay of deformed superheavy nuclei

Abstract

We explore the impact of the density-dependent nuclear symmetry energy on the properties and stability of superheavy nuclei (SHN) based on a deformed relativistic mean-field theory in combination with the BCS method. The interaction ‘family’ based on the well-established FSUGarnet parameter set is introduced by adjusting the nonlinear $\omega -\rho$ coupling parameter ${\Lambda }_{\text{V}}$ and ρ-nucleon coupling parameter $g_{\rho }$. This adjustment allows us to explore various density-dependent behaviors of the symmetry energy while maintaining its value at saturation density. A larger ${\Lambda }_{\text{V}}$ gives larger symmetry energy (but softer due to its small slope) below the saturation density. Under different density-dependent behavior of symmetry energy, the nuclear deformation remains largely unchanged, and the nuclear magicity is also almost not altered distinctly although the single-particle energy levels shift evidently. Intriguingly, although the shell gaps are not altered obviously, the stability of SHN against α-decay is enhanced substantially as the symmetry energy softens because a softer symmetry energy gives a smaller α-decay energy and a much longer lifetime.