Observation of the Charge-Exchange Mode of the Giant $M1\mathrm{}$ Resonance of ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$

The reaction ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}(t,{}_{}{}^3{}_{}{}^{}\mathrm{He}){}_{}{}^{28}{}_{}{}^{}\mathrm{Al}$ has been performed at a bombarding energy of 23.5 MeV. A number of low-lying $1^{+}$ states are observed in the spectrum of ${}_{}{}^{28}{}_{}{}^{}\mathrm{Al}$ and these are related by the Coulomb energy difference to their analog $1^{+}$, $T=1\mathrm{}$ states which comprise the giant $M1\mathrm{}$ resonance structure of ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$. Of particular importance, the ($t,{}_{}{}^3{}_{}{}^{}\mathrm{He}$) strength distribution to the $1^{+}$ states in ${}_{}{}^{28}{}_{}{}^{}\mathrm{Al}$ largely reproduces the distribution of electromagnetic transition rates of their analogs in Si. This provides strong evidence for the existence of the charge-exchange mode with $\Delta T_z=1\mathrm{}$ of the giant $M1\mathrm{}$ resonance in ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$.