Detection of inelastically scattered alpha particles near 180° from the reaction 18O(α,α′)18O has been used to identify natural parity levels in 18O. Energy spectra were recorded for 13 incident energies from 20.0 to 23.4 MeV. Levels at 4.45, 5.09, and 5.25 MeV have been identified as having natural parity, confirming earlier assignments of 1−, 3−, and 2+, respectively. Levels at 5.37 and 5.52 MeV have been identified as having unnatural parity leading to definite assignments of 3+ and 2−, respectively. The spin and parity of the 6.18 MeV level has been restricted to 1− or 2+. Other levels at higher excitation energies have been assigned natural parity, and the implications with regard to the identification of a negative parity band in 18O are discussed.
Spin-parity analysis of the decay distributions of unnatural parity mesons
