The dynamic mechanism of the Thomas-Ehrman shift in three-cluster systems is studied by example of 16 Ne and 16 C isobaric mirror partners. We predict configuration mixings for 0 + and 2 + states in 16 Ne and 16 C. Large isospin symmetry breaking on the level of wave function component weights is demonstrated for these states and discussed as three-body mechanism of Thomas-Ehrman shift. It is shown that the description of the Coulomb displacement energies requires a consistency among three parameters: the 16 Ne decay energy ET , the 15 F ground state energy Er, and the configuration mixing parameters for the 16 Ne/ 16 C 0 + and 2 + states. Basing on this analysis we infer the 15 F 1/2 + ground state energy to be Er = 1.39 − 1.42 MeV.

Previously unknown isotopes30 Ar and 29 Cl have been identified by measurement of the trajectories of their in-flight decay products 28 S þ p þ p and 28 S þ p, respectively. The analysis of angular correlations of the fragments provided information on decay energies and the structure of the parent states. The ground states of 30 Ar and 29 Cl were found at 2.25 þ0.15 −0.10 and 1.8 AE 0.1 MeV above the two-and one-proton thresholds, respectively. The lowest states in 30 Ar and 29 Cl point to a violation of isobaric symmetry in the structure of these unbound nuclei. The two-proton decay has been identified in a transition region between simultaneous two-proton and sequential proton emissions from the 30 Ar ground state, which is characterized by an interplay of three-body and two-body decay mechanisms. The first hint of a fine structure of the two-proton decay of 30 Ar à ð2 þ Þ has been obtained by detecting two decay branches into the ground and first-excited states of the 28 S fragment.

The first-excited, J π = 2 + state of 16 Ne at E * = 1.69(2) MeV is well populated in neutron knockout reactions with a 17 Ne beam and the correlations between the momenta of the three final fragments following 2p decay were measured. The correlation pattern showed aspects of both sequential and diproton-like decay, which were reproduced in three-body 14 O+p+p calculations. These calculations suggest that interference between these processes is responsible for the observed features which can be described in terms of a "tethered decay mechanism". The intrinsic width of this state was constrained to be from 100 to 250 keV. Higher excited states populating the 13 N+p+p+p exit channel were found at E

appear in the even-proton number (Z) isotopes beyond the proton drip-line, in which one-proton (1p) emission is energetically prohibited but the ejection of two protons is energetically allowed due to the pairing interaction. More than 40 years after its prediction, ground-state 2p radioactivity was discovered in 2002 [2,3]. Two experiments independently observed that the ground state (g.s.) of 45 Fe decays by simultaneous emission of two protons. Later 54 Zn [4], 19 Mg [5], 48 Ni [6], and 67 Kr [7] were found to be other g.s. 2p radioactive nuclei. Among the g.s. 2p emitters hitherto observed, the halflives of 45 Fe, 48 Ni, and 54 Zn are in the range of several ms,

Transitions among different mechanisms of two-proton decay are studied in general. The introduced improved direct-decay model generalizes the semi-analytical models used before and provides flawless phenomenological description of three-body correlations in 2p decays. This is demonstrated by examples of the low-lying 16 Ne state decays. Different forms of transition dynamic are shown to be highly probable beyond the proton dripline for the s-d shell nuclei. It is demonstrated that transition dynamic of 2p emitters can provide means for extraction of a width of the ground-state resonance of a core+p subsystem of the core+2p system. Practical applicability of the method is demonstrated by properties of the 14 F ground state derived from the 15 Ne → 13 O + 2p decay data and of the 29 Cl ground state derived from the 30 Ar → 28 S + 2p decay data.