Possible Identification of10+Levels inMg24atEx≳20MeV

Enhanced population of ${}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}$ states at $E_x=20.1, 21.3, 23.5, \mathrm{and} 28.2$ MeV is observed in the reaction ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}({}_{}{}^{16}{}_{}{}^{}\mathrm{O}, \alpha ){}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}$ at $E_{\mathrm{c}.\mathrm{m}.\mathrm{}}=26.7\mathrm{}$ MeV, an energy where the ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ + ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ inelastic channel also exhibits structure. It is suggested that the 28.2-MeV state may be identified with the ${10}^{+}$ member of a postulated excited collective band. $J^{\pi }={10}^{+}$ assignments for the other states are consistent with their decay modes observed in a particle-$\gamma$ coincidence experiment and their excitation energies are suggestively close to recent shell-model calculations.