Isotopic spin selection rules X: The 7.18 MeV state of 20Ne

Abstract The possible E1 transition between the 3– state at 7.18 MeV and the 2+ state at 1.63 MeV in 20Ne is forbidden by the isotopic spin rule. It has been sought using the reaction 16O(α, γ)20Ne and it has been shown that the radiative width is less than 6 MeV. This corresponds to ∥ M ∥2 ⩽4.3×10×5 in Weisskopf Units or to contaminations α2 0(1) ⩽1.3×10×3 of the 7.18 and 1.63 MeV states with T = 1 states.