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

Several states of proton-unbound isotopes 30Ar and 29Cl were investigated by measuring their in-flight decay products, 28S + proton + proton and 28S + proton, respectively. A refined analysis of 28S-proton angular correlations indicates that the ground state of 30Ar is located at 2.45+0.05-0.10 MeV above the two-proton emission threshold. The investigation of the decay mechanism of the 30Ar 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 30Ar ground state and the one-proton decay energy as well as the one-proton decay width of the 29Cl ground state. The comparison of the experimental 28S-proton angular correlations with those resulting from Monte Carlo simulations of the detector response illustrates that other observed 30Ar excited states decay by sequential emission of protons via intermediate resonances in 29Cl. Based on the findings, the decay schemes of the observed states in 30Ar and 29Cl 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 19Mg were remeasured. Evidences for one new excited state in 19Mg and two unknown states in 18Na were found.This work was supported in part by the Helmholtz International Center for FAIR (HIC for FAIR), the Helmholtz Association (grant IK-RU-002), the Russian Ministry of Education and Science (grant No. NSh- 932.2014.2), the Russian Science Foundation (grant No. 17-12-01367), the Polish National Science Center (Contract No. UMO-2011/01/B/ST2/01943), the Polish Ministry of Science and Higher Education (Grant No. 0079/DIA/2014/43,Grant Diamentowy), the Helmholtz- CAS Joint Research Group (grant HCJRG-108), the FPA2009-08848 contract (MICINN, Spain), the Justus- Liebig-Universit¨at Gießen (JLU) and GSI under the JLUGSI strategic Helmholtz partnership agreement. This article is a part of PhD thesis of X.-D. Xu. The authors acknowledge the help of D. Kostyleva in the preparation of the manuscript.This work was supported in part by the Helmholtz International Center for FAIR (HIC for FAIR), the Helmholtz Association (Grant No. IK-RU-002), the Russian Ministry of Education and Science (Grant No. NSh-932.2014.2), the Russian Science Foundation (Grant No. 17-12-01367), the Polish National Science Center (Contract No. UMO-2011/01/B/ST2/01943), the Polish Ministry of Science and Higher Education (Grant No. 0079/DIA/2014/43, Grant Diamentowy), the Helmholtz-CAS Joint Research Group (Grant No. HCJRG-108), the FPA2009-08848 contract (MICINN, Spain), and the Justus-Liebig-Universitat Giessen (JLU) and GSI under the JLU-GSI strategic Helmholtz partnership agreement. This article is a part of the Ph.D. thesis of X.-D. Xu. The authors acknowledge the help of D. Kostyleva in the preparation of the manuscript

Elastic scattering of Be 7 + Si 28 at near-barrier energies

The elastic scattering of the radioactive nucleus Be7 from a Si28 target was studied at four near-barrier energies: 13.2, 17.2, 19.8, and 22.0 MeV (E/VC=1.14, 1.48, 1.71, and 1.90). Angular distribution measurements were performed at each energy with the multidetector array EXPADES in conjunction with two Parallel-Plate Avalanche Counters (PPAC) to enable beam ray reconstruction of the events. The data are analyzed in a double-folding framework and the energy evolution of the optical potential as well as the total reaction cross sections are deduced and discussed. © 2017 American Physical Society

Elastic scattering of Be7+Si28 at near-barrier energies

The elastic scattering of the radioactive nucleus Be7 from a Si28 target was studied at four near-barrier energies: 13.2, 17.2, 19.8, and 22.0 MeV (E/VC=1.14, 1.48, 1.71, and 1.90). Angular distribution measurements were performed at each energy with the multidetector array EXPADES in conjunction with two Parallel-Plate Avalanche Counters (PPAC) to enable beam ray reconstruction of the events. The data are analyzed in a double-folding framework and the energy evolution of the optical potential as well as the total reaction cross sections are deduced and discussed