Radiative decays of unbound levels in 20Ne

Abstract Nine levels in the range 8.7 to 12.5 MeV in 20 Ne have been investigated with the 16 O(α, γ) 20 Ne and 16 O(α, α') 16 O ∗ (6.13 MeV) reactions using a differentially pumped windowless gas target. Three of the levels have not been observed previously in these reactions, and new information has been obtained for most of the others. In particular, the 11.27 MeV 1 − level is shown to have T = 1, a result of relevance to a proposed parity violation experiment, and the analogue of the 1.97 MeV (3 − T = 1) level in 20 F is shown to lie at 12.25 MeV in 20 Ne rather than at 12.39 MeV as proposed previously. In addition, the 12.25 MeV level has a width Γ Γ ∼ 5 keV reported in other work. The electromagnetic transition rates for positive parity T = 1 states in 20 Ne are compared with shell-model calculations.