Fusion of Borromean nucleus $^{9}$Be with $^{197}$Au target at near barrier energies

TL;DR

This study measures and analyzes the fusion cross sections of the $^{9}$Be + $^{197}$Au system near the Coulomb barrier, revealing the influence of projectile structure and deformation on sub-barrier fusion, with theoretical modeling showing good agreement.

Contribution

It provides new experimental fusion data for $^{9}$Be + $^{197}$Au and demonstrates the importance of projectile deformation and structure in sub-barrier fusion, validated by coupled-channel calculations.

Findings

Coupled-channel calculations match sub-barrier fusion data well.

Fusion cross section is suppressed by about 39% above barrier.

$^{9}$Be shows larger sub-barrier enhancement compared to other projectiles.

Abstract

To probe the role of the intrinsic structure of the projectile on sub-barrier fusion, measurement of fusion cross sections has been carried out in $^{9}$Be + $^{197}$Au system in the energy range E$_{c.m.}$/V$_B$ $\approx$ 0.82 to 1.16 using off-beam gamma counting method. Measured fusion excitation function has been analyzed in the framework of the coupled-channel approach using CCFULL code. It is observed that the coupled-channel calculations, including couplings to the inelastic state of the target and the first two states of the rotational band built on the ground state of the projectile, provide a very good description of the sub-barrier fusion data. At above barrier energies, the fusion cross section is found to be suppressed by $\approx$ 39(2)\% as compared to the coupled-channel prediction. A comparison of reduced excitation function of $^{9}$Be + $^{197}$Au with other $x$ + $^{197}$Au shows a larger enhancement for $^9$Be in the sub-barrier region amongst Z=2-5 weakly and tightly bound projectiles, which indicates the prominent role of the projectile deformation in addition to the weak binding.