Spectroscopy of ${}^{18}$Na: Bridging the two-proton radioactivity of ${}^{19}$Mg

Abstract

The unbound nucleus ${}^{18}$Na, the intermediate nucleus in the two-proton radioactivity of ${}^{19}$Mg, was studied by the measurement of the resonant elastic scattering reaction ${}^{17}$Ne(p,${}^{17}$Ne)p performed at 4 A.MeV. Spectroscopic properties of the low-lying states were obtained in a R-matrix analysis of the excitation function. Using these new results, we show that the lifetime of the ${}^{19}$Mg radioactivity can be understood assuming a sequential emission of two protons via low energy tails of ${}^{18}$Na resonances.