Deformed two-neutron halo in 19B

Ground state properties of B-19 are studied by using the deformed relativistic Hartree-Bogoliubov theory in continuum. The calculations with the density functional PK1 show that B-19 is a deformed two-neutron (2n) halo nucleus. By examining the evolution of single neutron levels, it is found that the valence levels, which are weakly bound or embedded in the continuum due to pairing, contain considerable s-wave components with the probability amplitude of 0.359 and lead to the formation of the halo. Strong quadrupole correlations mix sd orbitals and drive B-19 to be prolate. The calculated density of the neutron core presents a prolate shape while the neutron halo is oblate, meaning B-19 is a 2n halo candidate with shape decoupling effects.

Automated summary

Ground state properties of B-19 were studied using the deformed relativistic Hartree-Bogoliubov theory in continuum. The calculations with the density functional PK1 revealed that B-19 is a deformed two-neutron halo nucleus with shape decoupling effects. Strong quadrupole correlations mix sd orbitals and drive B-19 to be prolate, with the neutron core presenting a prolate shape and the neutron halo being oblate.