New states in18Na and19Mg observed in the two-proton decay of19Mg

Abstract

Previously unknown states in 18 Na and 19 Mg have been studied by measuring the trajectories of their decay products with microstrip detectors. Analyzing angular correlations of the fragments provided information on decay energies and widths of the parent states. The ground state of 18 Na has been detected and its one-proton decay energy of 1.23(15) MeV determined. Four previously unknown states in 19 Mg at 2.1, 2.9, 3.6, and 5.2 MeV have been observed. The competition between simultaneous and sequential two-proton emission of states in 19 Mg is discussed, and the conclusion of a direct mechanism of 2p radioactivity of the 19 Mg ground state is confirmed.

Observation and Spectroscopy of New Proton-Unbound IsotopesAr30andCl2

“…has confirmed the peaks related to 19 Mg resonances with the total 2p-decay energy E 2p ∼ ρ 2 θ [16,17]. The observed peaks at 0.85(12), 2.1(3), and 5.3(4) MeV are consistent with the previous measurements [17].…”

“…The observed peaks at 0.85(12), 2.1(3), and 5.3(4) MeV are consistent with the previous measurements [17]. The half-life T 1=2 of the 19 Mg ground state (g.s.)…”

“…2(c), we obtain the angular θð 28 S-pÞ distributions which reflect energy spectra of protons emitted from the suggested parent states in 30 Ar. This technique has successfully been used for revealing the structure and decay dynamics of 19 Mg [17]. Three such correlations gated by the lowest ρ θ peaks A, B, and C [see …”

Mg19two-proton decay lifetime

“…From the measured proton- 17 Ne angular correlations, the authors determined the prompt contribution of the 17 Ne yield to be 89(1)% [35] from the analysis presented in Ref. [36].…”

“…First, calculations of p-wave neutron removal from the 20 Mg secondary beam to the 1/2 − ground state and low-lying 3/2 − excited states in 19 Mg [36] were performed. The results indicated a modest 4% increase in both 19 Mg ground state production-the only source of delayed 17 Ne-and excited state production-one source of prompt 17 Ne-for our work compared to Ref.…”