Abstract
The structure of the 18O nucleus at excitation energies above the α decay threshold was studied using 14C+α resonance elastic scattering and (7Li,t) a-transfer reactions. A number of states with large α reduced widths have been observed, indicating that the a-cluster degree of freedom plays an important role in this NZ nucleus. A 0+ state with an α reduced width exceeding the single particle limit was identified at an excitation energy of 9.90.3 MeV. We discuss evidence that states of this kind are common in light nuclei and give possible explanations of this feature. Also, the astrophysical implications of the cluster structure of 18O is discussed. © 2010 IOP Publishing Ltd.