Microscopic three-cluster study of 20O, 20Mg and 19N, 19Mg exotic nuclei

The 20O and 19N neutron-rich nuclei are studied in a 16O+2n+2n and 15N+2n+2n three-cluster model respectively. The mirror systems are also analyzed without approximation on the Coulomb force. Spectroscopic properties of 20O and 20Mg are in reasonable agreement with experiment, and do not show evidence for an exotic structure. The 19Mg ground state is predicted to be close to particle stability.