Channel-Coupling Effects in Analog Charge-Exchange Reactions

Abstract

We present data and coupled-channel calculations on charge-exchange reactions in ${}_{}{}^{56}{}_{}{}^{}\mathrm{Fe}$ and ${}_{}{}^{26}{}_{}{}^{}\mathrm{Mg}$ to $0^{+}$ and $2^{+}$ analog states. For the ($p,n$) reaction in the neighborhood of 20 MeV the two-step processes dominate the excited $2^{+}$ analog transitions, thus explaining the large strength of these states in the ($p,n$) spectrum. The two-step mechanism is relatively weaker but still important in the corresponding (${}_{}{}^3{}_{}{}^{}\mathrm{He},t$) reaction.