Isospin Forbidden Resonances in the ReactionNb93(p,α)Zr90

Isospin forbidden resonances ($\Delta T=1\mathrm{}$) have been observed in the reaction ${}_{}{}^{93}{}_{}{}^{}\mathrm{Nb}(p,\alpha ){}_{}{}^{90}{}_{}{}^{}\mathrm{Zr}$. Angular distributions to the $0^{+}$ ground state measured at the $4^{+}$ (59-keV) and $2^{+}$ (334-keV) analog resonances indicate that the $2^{+}$ isospin analog state is formed via a pure $d_{\frac{5}{2}}$ capture whereas the $4^{+}$ isospin analog state is formed by a coherent admixture of $d_{\frac{5}{2}}$, $s_{\frac{1}{2}}$, and $d_{\frac{3}{2}}$ components.