Sensitivity of $^{107,109}$Ag($\alpha$,xn) cross sections to statistical-model inputs

Abstract

The $\alpha$-induced reactions on silver isotopes leading to the production of the medically relevant radionuclides $^{108m,109g,110m,110g,111g}$In have been systematically analyzed using the TALYS~2.0 code. A total of 192 combinations of nuclear reaction model parameters, comprising level-density models (LDM), $\alpha$-optical model potentials ($\alpha$OMP), and pre-equilibrium (PE) models, were evaluated through $\chi^2$ minimization against the available experimental data. The results reveal pronounced channel-dependent sensitivities of the statistical-model ingredients. The $^{107}$Ag($\alpha$,3n)$^{108m}$In and $^{109}$Ag($\alpha$,3n)$^{110g}$In reactions are primarily governed by the LDM. For the $^{107}$Ag($\alpha$,2n)$^{109g}$In reaction, the sensitivities to the LDM and PE mechanism are comparable, indicating that both contribute nearly equally to reproducing the experimental data. In contrast, the $^{107}$Ag($\alpha$,n)$^{110m}$In and $^{109}$Ag($\alpha$,2n)$^{111g}$In reactions are dominated by the PE mechanism, while the $\alpha$OMP plays a secondary role and the LDM has only a minor influence. These findings demonstrate that the relative importance of the statistical-model ingredients varies significantly among the investigated reaction channels. Differences between the present TALYS calculations and the TENDL-2023 evaluation are attributed to the absence of parameter optimization in the present study. Overall, the analysis shows that no single parameter combination provides the best description of all investigated reactions. The observed channel-dependent sensitivities provide useful guidance for selecting and evaluating TALYS model ingredients for the studied reaction channels and motivate future work incorporating additional experimental data and model-uncertainty quantification.