The radiative width of the lowest T=1 state of 20Ne and fundamental β-decay studies

Ge(Li) detector observations of the 16O(α,γ)20Ne reaction and a measurement of the stopping cross section for 6.93 MeV α-particles in anodized tantalum (Ta2O5) targets are combined with previous β-delayed γ- and α-observations of 20Ne(10.27 MeV, T=1) decay to obtain the partial decay widths. The values obtained are GAMMAsub(γ)=4.08+-0.33 eV for the 8.64 MeV γ-transition to the first excited state, and GAMMAsub(α)=116+-20 eV for the isospin forbidden α-decay to 16O. The γ-decay is discussed in relation to model calculations, to a test of the conserved vector current hypothesis and to possible second-class-current effects in the analogous β+- decays of 20Na and 20F. The small α-decay width is used to set an isospin impurity limit of less than about 1% for 20Ne(10.27 MeV, T=1). (Auth.)