Isospin mixing inIn111and the inclusion of additional terms in the mixing formalism

Abstract

The extent of isospin mixing in ${}_{}{}^{111}{}_{}{}^{}\mathrm{In}$ has been determined at 20.9 MeV on the basis of measured cross sections for the ($p, p^{\prime }$), ($p, \alpha$), ($\alpha , p$) and ($\alpha , {\alpha }^{\prime }$) reactions involving the formation of the ${}_{}{}^{111}{}_{}{}^{}\mathrm{In}$ compound nucleus. The following values were obtained for the mixing fraction and the isospin mixing matrix element: $\mu =0.62\mathrm{}\pm 0.14$ and $\left|H_c\right|=0.013\mathrm{}\pm 0.004$ eV. These results are based on a reformulation of the isospin mixing theory in which additional terms are included. Previous data available for the $A\sim 50-70$ region are reanalyzed using this formalism and the dependence of $\left|H_c\right|$ on energy, mass number, and the probability of proton emission from the $T_{<}\left(\mathrm{nonanalog}\right)$ states of the compound nucleus is determined. $\left|H_c\right|$ varies inversely with the first two of these quantities and directly with the third.