Year: 2018
Type: article
Abstract: Background: Since the first experimental observation, two-nucleon radioactivity has gained renewed attention since the early 2000s. The $^{6}\mathrm{Be}$ system is the lightest two-proton ground-state emitter, while $^{16}\mathrm{Be}$ was recently proposed to be the first two-neutron ground-state emitter ever observed. A proper understanding of their properties and decay modes requires a reasonable description of the three-body continuum.Purpose: Study the ground-state properties of $^{6}\mathrm{Be}$ and $^{16}\mathrm{Be}$ within a general three-body model and investigate their nucleon-nucleon correlations in the continuum.Method: The pseudostate (PS) method in hyperspherical coordinates, using the analytical transformed harmonic oscillator (THO) basis for three-body systems, is used to construct the $^{6}\mathrm{Be}$ and $^{16}\mathrm{Be}$ ground-state wave functions. These resonances are approximated as a stable PS around the known two-nucleon separation energy. Effective core-$N$ potentials, constrained by the available experimental information on the binary subsystems $^{5}\mathrm{Li}$ and $^{15}\mathrm{Be}$, are employed in the calculations.Results: The ground state of $^{16}\mathrm{Be}$ is found to present a strong dineutron configuration, with the valence neutrons occupying mostly an $l=2$ state relative to the core. The results are consistent with previous $R$-matrix calculations for the actual continuum. The case of $^{6}\mathrm{Be}$ shows a clear symmetry with respect to its mirror partner, the two-neutron halo $^{6}\mathrm{He}$: The diproton configuration is dominant, and the valence protons occupy an $l=1$ orbit.Conclusions: The PS method is found to be a suitable tool in describing the properties of unbound $\text{core}+N+N$ ground states. For both $^{16}\mathrm{Be}$ and $^{6}\mathrm{Be}$, the results are consistent with previous theoretical studies and confirm the dominant dinucleon configuration. This favors the picture of a correlated two-nucleon emission.
Source: Physical Review C
Author: J. Casal
Language: Latvian
Subfield: Nuclear and High Energy Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W2782279018