Correlations of two protons emitted from excited states of 28S and 27P

A contrastive research on two-proton (2p) emissions from excited states of the even-Z nucleus 28S and its one-proton daughter, the odd-Z nucleus 27P was performed by complete-kinematics measurements. The opening angles as well as relative momenta between two emitted protons and invariant masses of decaying systems were reconstructed through the event-by-event analysis of heavy fragments coincident with two protons. With the help of Monte Carlo simulations, results show a diproton-type decay with the branching ratio of 20−7+6% for 28S while mainly three-body simultaneous decay in the phase space and/or 2p sequential emission for 27P. Present results show that the diproton correlations may result from the proton configuration in the initial state like 2p skin/halo structure rather than the deformed orbit.