Evidence for a doubly magic O

The decay energy spectrum for neutron unbound states in ²⁴O (Z=8$Z=8$, N=16$N=16$) has been observed for the first time. The resonance energy of the lowest lying state, interpreted as the ²⁺$2^{+}$ level, has been observed at a decay energy above 600 keV. The resulting excitation energy of the ²⁺$2^{+}$ level above 4.7 MeV, supplies strong evidence that ²⁴O is a doubly magic nucleus. The data is also consistent with the presence of a second excited state around 5.33 MeV which can be interpreted as the ¹⁺$1^{+}$ level.