197Au(n, γ) - towards a new standard for energies relevant to stellar nucleosynthesis

Abstract

Two experiments were performed to resolve a discrepancy of the 197Au(n, γ) cross section between the IAEA standard evaluation and the reference cross section for astrophysical experiments in the lower keV energy region. We measured the 197Au(n, γ) reaction by means of the time-of-flight technique with n_TOF at CERN and extracted the cross section in the unresolved resonance region between 5-400 keV with an overall uncertainty from 3.9-6.7% for a resolution of 20 bins per energy decade. Additionally, we remeasured the neutron spectrum of the 7Li(p, n)7Be reaction with Ep = 1912 keV, which was used as a neutron source for determining the astrophysical reference cross section. The n_TOF data are already fully analyzed and published. The results are in good agreement with the ENDF standard evaluation, but uncertainties don't allow to draw definite conclusions. The analysis of the neutron spectrum of 7Li(p, n)7Be is underway, preliminary results will be reported here.