Observation of two-proton radioactivity of Mg19 by tracking the decay products

Abstract

We have observed the two-proton radioactivity of the previously unknown 19Mg ground state by tracking the decay products in-flight. For the first time, the trajectories of the 2p-decay products, 17Ne+p+p, have been measured by using tracking microstrip detectors which allowed us to reconstruct the 2p-decay vertices and fragment correlations. The half-life of 19Mg deduced from the measured vertex distribution is 4.0(15) ps in the system of 19Mg. The Q value of the 2p decay of the 19Mg ground state inferred from the measured p−p−17Ne correlations is 0.75(5) MeV.