Spectroscopy of excited states of unbound nuclei 30 Ar and 29 Cl

Several states of proton-unbound isotopes 30 Ar and 29 Cl were investigated by measuring their in-flight decay products, 28 S + proton + proton and 28 S + proton, respectively. A refined analysis of 28 S -proton angular correlations indicates that the ground state of 30 Ar is located at 2 . 45 + 0.05 − 0.10 MeV above the two-proton emission threshold. The investigation of the decay mechanism of the 30 Ar ground state demonstrates that it has the transition dynamics. In the “transitional” region, the correlation patterns of the decay products present a surprisingly strong sensitivity to the two-proton decay energy of the 30 Ar ground state and the one-proton decay energy as well as the one-proton decay width of the 29 Cl ground state. The comparison of the experimental 28 S -proton angular correlations with those resulting from Monte Carlo simulations of the detector response illustrates that other observed 30 Ar excited states decay by sequential emission of protons via intermediate resonances in 29 Cl . Based on the findings, the decay schemes of the observed states in 30 Ar and 29 Cl were constructed. For calibration purposes and for checking the performance of the experimental setup, decays of the previously known states of a two-proton emitter 19 Mg were remeasured. Evidences for one new excited state in 19 Mg and two unknown states in 18 Na were found.Helmholtz International Center for FAIR de Alemania (HIC for FAIR) IK-RU-002Russian Ministry of Education and Science. NSh-932.2014.2Russian Science Foundation. 17-12-01367Polish National Science Center. UMO-2011/01/B/ST2/01943Polish Ministry of Science and Higher Education. 0079/DIA/2014/43HelmholtzCAS Joint Research Group de Alemania. HCJRG-108Ministerio de Ciencia, Innovación y Universidades de España (MICINN). FPA2009-0884