Cross section of the 13C(α,n)16O reaction at low energies

Abstract

The 13C(α, n)16O reaction is the main neutron source for the s-process in low mass AGB stars. Although several direct measurements have been performed, no dataset reaches the Gamow window (140-250 keV) due to the the exponential drop of the cross section σ(E) with decreasing energy. The reaction rate becomes so low that the strong cosmic background would become predominant.In order to measure the 13C(α, n)16O cross section at low energies, a double effort has been performed, namely to suppress the background in the setup and to keep under control the target modification under an intense stable beam provided by the LUNA accelerator (100-200 µA). These measurements were carried out in deep underground laboratories of Laboratori Nazionali del Gran Sasso (LNGS) in the framework of the LUNA experiment. Preliminary results are reported in this contribution.