Borromean structures in medium-heavy nuclei

TL;DR

This paper investigates borromean two-alpha cluster structures in medium-heavy nuclei, especially $^{142}$Ba, revealing surface localization of alpha particles and predicting specific structural configurations and experimental signatures.

Contribution

It identifies promising regions for borromean structures in medium-heavy nuclei and characterizes their properties, including detailed analysis of $^{142}$Ba and its alpha-cluster configurations.

Findings

Alpha particles are surface-localized due to Coulomb and centrifugal barriers.

The lowest three-body bound states resemble a contracted $^{8}$Be nucleus.

Predicted specific alpha-cluster structures in $^{142}$Ba with experimental signatures.

Abstract

Borromean nuclear cluster structures are expected at the corresponding driplines. We locate the regions in the nuclear chart with the most promising constituents, it being protons and alpha-particles and investigate in details the properties of the possible borromean two-alpha systems in medium heavy nuclei. We find in all cases that the alpha-particles are located at the surface of the core-nucleus as dictated by Coulomb and centrifugal barriers. The two lowest three-body bound states resemble a slightly contracted $^{8}\text{Be}$ nucleus outside the core. The next two excited states have more complex structures but with strong components of linear configurations with the core in the middle. Alpha-removal cross sections would be enhanced with specific signatures for these two different types of structures. The even-even borromean two-alpha nucleus, $^{142}$Ba, is specifically investigated and predicted to have $^{134}\text{Te}-\alpha-\alpha$ structure in its ground state and low-lying spectrum.