The ground state two-proton decay lifetime of ${}^{19}\mathrm{Mg}$, populated by the one-neutron knockout of an intermediate-energy ${}^{20}\mathrm{Mg}$ radioactive beam, was measured utilizing a new experimental technique. A thin silicon detector positioned at varying distances (0.0–1.0 mm) downstream of the reaction target measured the energy loss of ${}^{19}\mathrm{Mg}$ and the two-proton decay product ${}^{17}\mathrm{Ne}$. The lifetime was deduced from fits to the measured energy-loss line shapes and depended upon the contribution of prompt reaction processes to the yield of ${}^{17}\mathrm{Ne}$. For relative ${}^{17}\mathrm{Ne}$ prompt contributions from 82% to 92%, the extracted lifetimes ranged from $1.{75}_{-0.42}^{+0.43}$ to $6.4_{-2.7}^{+2.4}$ ps. The results are consistent with the previously reported ${}^{19}\mathrm{Mg}$ lifetime measurement and serve as both an important complementary study and a validation of this new technique, which can provide lifetime information for short-lived states beyond the proton drip line.

• Received 5 May 2014

DOI:https://doi.org/10.1103/PhysRevC.90.014301