Neutron activation of Ga-69 and Ga-71 at k(B)T approximate to 25 keV

Background: About 50% of heavy elements are produced by the slow neutron capture process (s process) in stars. The element gallium is mostly produced during the weak s process in massive stars.Purpose: Our activation at kBT ≈ 25 keV is the first experiment in a series of activation and time-of-flight measurements on 69Ga and 71Ga relevant for astrophysics.Methods: We activated 69Ga and 71Ga with a neutron distribution that corresponds to a quasistellar distribution with kBT = 25 keV at the Joint Research Centre (JRC), Geel, Belgium. Protons were provided by an electrostaticVan de Graaff accelerator to produce neutrons via the reaction 7Li(p, n). The produced activity was measured via the γ emission by the decaying product nuclei by high-purity germanium detectors.Results: We provide spectrum-averaged cross sections (SACS) and ratios of the cross sections σGa/σAu for the neutron spectrum of the activation. We obtain values of σ69Ga,SACS = (186 ± 12) mb and σ71Ga,SACS = (112 ±7) mb, and cross-section ratios of σ69Ga/σAu = 0.29 ± 0.02 and σ71Ga/σAu = 0.17 ± 0.01.Conclusions: Our data disagree with the available evaluated data provided by KADoNiS v0.3, our cross-section ratio is about 20% higher for 69Ga and about 20% lower for 71Ga.