Average reaction cross sections for 74- to 112-MeV α particles on ${}_{}{}^{127}{}_{}{}^{}\mathrm{I}$ and ${}_{}{}^{133}{}_{}{}^{}\mathrm{Cs}$

The average reaction cross section for 74- to 112-MeV α particles on ${}_{}{}^{127}{}_{}{}^{}\mathrm{I}$ and ${}_{}{}^{133}{}_{}{}^{}\mathrm{Cs}$ was measured by a new method using a magnetic spectrograph and a CsI scintillation detector. The result, ${\mathrm{\sigma }}_{\mathit{R}}$=2220±50 mb, is in good agreement with optical model calculations and finite-range microscopic calculations. Zero-range microscopic calculations underpredict ${\mathrm{\sigma }}_{\mathit{R}}$ by about 10%, while strong absorption theories overpredict ${\mathrm{\sigma }}_{\mathit{R}}$ by large amounts.