The T = 1, isospin triplet states in A = 30 nuclei

The level structure of ³⁰S was studied using the ${}^{28}\text{Si}\text{(τ,}\text{n}\text{p}\text{)}\text{reaction at}\text{E}{}_{\mathrm{\tau }}\text{= 9.5}\text{MeV}\text{,}\text{and}\text{J}{}^{\mathrm{\pi }}$ values were determined for some proton-emitting states by the neutron-proton angular correlation measurements. The Coulomb displacement energy of the isospin triplet state of A = 30 nuclei was analyzed using first-order perturbation theory. Large deviations from perturbation theory were found for the ground state, the 2⁺₁ state, the 3^?₁ state and the second excited 0⁺ state. These results might be explained by the effect of the pairing correlation of the two valence protons in ³⁰S under the assumption of charge symmetry for the nucleon-nucleon interaction.