Transition from direct to sequential two-proton decay in s-d shell nuclei

The transition between different mechanisms of two-proton decay in exotic nuclei and the governing physical conditions are generally studied. To perform this large-scale survey, the direct-decay model, which is widely used, was improved by generalizing the semi-analytical approaches used before. The improved model provides a flawless phenomenological description of three-body correlations in 2p decays, as is demonstrated by several examples of decays of low-lying states in 16Ne. Different transition mechanisms are shown to occur beyond the proton dripline for s-d shell nuclei. It is found that the transition dynamics of 2p-emitters allows the extraction of the width of the ground-state resonance of the core+p subsystem. The practical application of the method is illustrated by determining properties of the 14F ground state derived from the Ne15→O13+2p decay data, and of the 29Cl ground state derived from the Ar30→S28+2p decay data.