High-Spin States in the Continuum. II.Mg24

Abstract

The spins and parities of several states in ${}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}$ have been determined with a triple angular-correlation technique. These states were selectively populated in the ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}({}_{}{}^{12}{}_{}{}^{}\mathrm{C},\alpha ){}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}$ reaction, and decayed by $\alpha$-particle emission to the 1.63-MeV ($2^{+}$) state in ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$. The results are: 13.42 MeV, $6^{+}$; 13.84 MeV, $6^{+}$; 14.14 MeV, $8^{+}$; 15.15 MeV, $7^{-}$; 16.30 MeV, $8^{+}$; 16.55 MeV, $8^{+}$+$9^{-}$; 16.84 MeV, $8^{+}$. In addition, the spins of the following states were determined from the angular correlations of the $\alpha$ particles leading to the ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$ ground state: 12.83 MeV, $6^{+}$; 13.75 MeV, $5^{-}$; 16.46 MeV, $7^{-}$. A search was made for particle decays of the 11.86-MeV ($6^{+}$, $8^{+}$) and 13.20-MeV ($8^{+}$) states in ${}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}$; no particle decay branch was found for either state. Statistical-model calculations have been performed to investigate the usefulness of such calculations in assigning spins to states selectively populated in the ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}({}_{}{}^{12}{}_{}{}^{}\mathrm{C},\alpha ){}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}$ reaction.