Correlations between neutrons and protons near Fermi surface and $Q_{\alpha}$ of super-heavy nuclei

TL;DR

This study uses the WS4 mass model to analyze shell effects, correlations, and alpha decay energies in super-heavy nuclei, revealing new shell closures and their relation to the shell stability line.

Contribution

It predicts new shell closures and correlations near the Fermi surface, and investigates alpha decay energies in super-heavy nuclei using the WS4 model.

Findings

Most asymmetric nuclei with shell closures lie along the shell stability line.

Predicted double magic nuclei include $^{46}$Si and $^{78}$Ni.

Super-heavy nuclei $^{296}$118 and $^{298}$120 are near the shell stability line.

Abstract

The shell corrections and shell gaps in nuclei are systematically studied with the latest Weizs\"acker-Skyrme (WS4) mass model. We find that most of asymmetric nuclei with (sub)-shell closures locate along the shell stability line (SSL), $N=1.37Z+13.5$, which might be due to a strong correlation between neutrons and protons near Fermi surface. The double magicity of nuclei $^{46}$Si and $^{78}$Ni is predicted according to the corresponding shell gaps, shell corrections and nuclear deformations. The unmeasured super-heavy nuclei $^{296}$118 and $^{298}$120, with relatively large shell gaps and shell corrections, also locate along the SSL, whereas the traditional magic nucleus $^{298}$Fl evidently deviates from the line. The $\alpha$-decay energies of super-heavy nuclei with $Z=113-126$ are simultaneously investigated by using the WS4 model together with the radial basis function corrections. For super-heavy nuclei with large shell corrections, the smallest $\alpha$-decay energy for elements $Z=116$, 117 and 118 in their isotope chains locates at $N=178$ rather than $184$.