Subbarrier fusion reactions of an aligned deformed nucleus

TL;DR

This paper investigates how the orientation and alignment of a deformed, odd-mass nucleus affect heavy-ion fusion reactions near the Coulomb barrier, revealing that alignment can significantly enhance fusion cross sections and alter barrier distributions.

Contribution

It introduces a method to account for the deformation and alignment of a target nucleus in fusion reactions, showing their impact on cross sections and barrier distributions, especially for superheavy element synthesis.

Findings

Fusion cross sections are sensitive to magnetic substates.

Alignment can double the fusion cross section for side collisions.

Aligned nuclei can mimic the barrier distribution of a nucleus with negative hexadecapole deformation.

Abstract

We discuss heavy-ion fusion reactions of a well-deformed odd-mass nucleus at energies around the Coulomb barrier. To this end, we consider the $^{16}$O+$^{165}$Ho reaction and take into account the effect of deformation of $^{165}$Ho using the orientation average formula. We show that fusion cross sections are sensitive to magnetic substates of the target nucleus, and cross sections for the side collision, which are relevant to a synthesis of superheavy elements, may be enhanced by a factor of around two by aligning the deformed target nuclei. We also discuss the effect of alignment on the fusion barrier distribution. We find that, for a particular choice of alignment, the shape of barrier distribution becomes similar to a typical shape of barrier distribution for a deformed nucleus with a negative hexadecapole deformation parameter, $\beta_4$, even if the intrinsic $\beta_4$ is positive in the target nucleus.