High-spin spectrum of24Mg studied through multiparticle angular correlations

We describe the investigation of high-spin states in ${}^{24}$Mg populated with the ${}^{12}\mathrm{C}{{(}^{16}\mathrm{O},\ensuremath{\alpha})}^{24}\mathrm{Mg}$ reaction at 62- and 68-MeV beam energy. The excited states were established through the coincident detection of up to four $\ensuremath{\alpha}$ and $\ensuremath{\gamma}$ particles in complete decay cascades toward a final state of angular momentum zero, the ground state of either ${}^{20}$Ne or ${}^{16}$O. We describe a new analysis method for the angular correlations in such events and apply it with the goal to assign spin and parity to $\ensuremath{\alpha}$-unbound states in ${}^{24}$Mg. We establish a number of high-spin, natural-parity states between spins 6 and 12, including the lowest known ${10}^{+}$ and ${12}^{+}$ levels. The energy systematics of positive- and negative-parity high-spin states are compared to the predictions of modern shell-model calculations.