Angular distributions have been measured for $0^{+}$→$1^{+}$ transitions with the ${(}^{12}$C${,}^{12}$B) reaction on targets of ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$,${\mathrm{}}^{26}$Mg, ${}_{}{}^{54}{}_{}{}^{}\mathrm{Fe}$,${\mathrm{}}^{58}$Ni, and ${}_{}{}^{90}{}_{}{}^{}\mathrm{Zr}$ and with the ${(}^{12}$C${,}^{12}$N) reaction on targets of ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ and ${}_{}{}^{56}{}_{}{}^{}\mathrm{Fe}$. The bombarding energy was E/A=70 MeV, and small-angle data were obtained. A comparison of the cross sections measured for the ${(}^{12}$C${,}^{12}$B) reaction with the results of distorted-wave-approximation calculations indicates that $0^{+}$→$1^{+}$ transitions are predominantly one step at E/A=70 MeV. The calculated cross sections are generally in good agreement (to within 40% in magnitude) with the measured cross sections, and the angular distributions are well described quantitatively in many cases. A correlation between cross sections and known Gamow-Teller (GT) strengths B(GT) for the corresponding transitions has been found. This correlation, which is weakly dependent on the target mass, establishes a calibration for the reactions. It is used to determine B(GT) values of astrophysical interest for two low-lying $1^{+}$ levels in ${}_{}{}^{56}{}_{}{}^{}\mathrm{Mn}$ from the cross sections measured for the ${}_{}{}^{56}{}_{}{}^{}\mathrm{Fe}$${(}^{12}$C${,}^{12}$N${)}^{56}$Mn reaction. The results are compared with two shell-model calculations performed to obtain B(GT) for ${}_{}{}^{56}{}_{}{}^{}\to _{}^{56}{}_{}{}^{}$Mn transitions and with another calculation from the literature. Computational tests were performed to evaluate (a) the contribution to the cross sections of terms not present in nucleon-induced charge-exchange reactions and (b) the extent to which the cross sections provide a measure of GT strength.

• Received 11 February 1991

DOI:https://doi.org/10.1103/PhysRevC.44.398