We study the ground and excited resonance states of O26 with a three-body model of O24+n+n taking into account the coupling to the continuum. To this end, we use the new experimental data for the invariant mass spectroscopy of the unbound O25 and O26 nuclei, and present an update of three-body model calculations for the two-neutron decay of the O26 nucleus. With the new model inputs determined with the ground-state decay of O26, we discuss the dineutron correlations and a halo nature of this nucleus, as well as the structure of the excited states. For the energy of the 2+ state, we achieve an excellent agreement with the experimental data with this calculation. We show that the 2+ state consists predominantly of the (d3/2)2 configuration, for which the pairing interaction between the valence neutrons slightly decreases its energy from the unperturbed one. We also discuss the structure of excited 0+ states of the O26 nucleus. In particular, we show the existence of an excited 0+ state at 3.38 MeV, which is mainly composed of the (f7/2)2 configuration.
ASJC Scopus subject areas
- Nuclear and High Energy Physics