Measurement of 107Ag(α,γ)111In Cross Sections

Cross sections have been measured for the 107Ag(α,γ)111In reaction at several α-particle energies between 7.8 MeV and 11.9 MeV. This reaction is of interest because it can provide a check on calculations of low-energy (α,γ) cross sections required for stellar nucleosynthesis predictions. Stacks of natural Ag foils of 1 μm thickness and 99.97% purity were bombarded with 4He+ beams. Following irradiation, the yields of the 171-keV and 245-keV photons produced in the 2.805-day electron-capture decay of the 111In product nucleus were measured off-line. The Ag foils were interleaved with 99.6% purity, 6-μm-thick natural Ti foils so that known cross sections for the 48Ti(α,n) reaction could be used to check the accuracy of the beam current integration. For any given beam energy, beam energy degradation in the foils resulted in lower effective bombarding energies for successive foils in the stack, enabling measurements to be made for several energies per irradiation. The measured cross sections are compared with published statistical-model calculations