Fusion of spherical-octupole pairs of colliding nuclei for compact and elongated configurations

The deformation and associated optimum/uniquely fixed orientations play an important role in the synthesis of compound nuclei via cold and hot fusion reactions, respectively, at the lowest and highest barrier energies. The choice of optimum orientation (\begin{document}$\theta_{\rm opt}$\end{document}) for the ‘cold or elongated’ and ‘hot or compact’ fusion configurations of quadrupole (\begin{document}$\beta_2$\end{document}) deformed nuclei depends only on the +/- signs of \begin{document}$\beta_2$\end{document}-deformation J. Phys. G: Nucl. Part. Phys. 31, 631-644 (2005)]. In our recent study Phys. Rev. C 101, 051601(R) 2020], we proposed a new set of \begin{document}$\theta_{\rm opt}$\end{document} (different from the values reported for quadrupole deformed nuclei) after the inclusion of octupole deformation (up to \begin{document}$\beta_3$\end{document}) effects. Using the respective \begin{document}$\theta_{\rm opt}$\end{document} of \begin{document}$\beta_3$\end{document}-deformed nuclei for cold and hot optimum orientations, we analyzed the impact of the soft- and rigid-pear shapes of octupole deformed nuclei on the fusion barrier characteristics (barrier height \begin{document}$V_B$\end{document} and barrier position \begin{document}$R_B$\end{document}). This analysis is applied to approximately 200 spherical-plus-\begin{document}$\beta_3$\end{document} deformed nuclear partners, that is, ¹⁶O, ⁴⁸Ca+octupole deformed nuclei. Compared with the compact configuration, the elongated fusion configuration has a relatively larger impact on the fusion barrier and cross-sections owing to the inclusion of deformations up to \begin{document}$\beta_3$\end{document}. Its agreement with available experimental data for the ¹⁶O+¹⁵⁰Sm reaction (\begin{document}$\beta_{22}$\end{document}=0.205, \begin{document}$\beta_{32}$\end{document}=-0.055) also improves when the optimum orientation degree of freedom is fixed in view of octupole deformations. This reinforces the fact that nuclear structure effects play an important role in the nuclear fusion process. Thus, octupole deformed nuclei can be used for the synthesis of heavy and superheavy nuclei.