Concurrent Application of ANC and THM to assess the 13C(α, n)16O Absolute Cross Section at Astrophysical Energies and Possible Consequences for Neutron Production in Low-mass AGB Stars

The C-13(alpha, n)O-16 reaction is considered to be the main neutron source responsible for the production of heavy nuclides (from Sr to Bi) through slow n-capture nucleosynthesis (s-process) at low temperatures during the asymptotic giant branch phase of low-mass stars (less than or similar to 3-4 M-circle dot, or LMSs). In recent years, several direct and indirect measurements have been carried out to determine the cross section at the energies of astrophysical interest (around 190 +/- 40 keV). However, they yield inconsistent results that cause a highly uncertain reaction rate and affect the neutron release in LMSs. In this work we have combined two indirect approaches, the asymptotic normalization coefficient and the Trojan horse method, to unambiguously determine the absolute value of the C-13(alpha, n)O-16 astrophysical factor. With these, we have determined a very accurate reaction rate to be introduced into astrophysical models of s-process nucleosynthesis in LMSs. Calculations using this recommended rate have shown limited variations in the production of those neutron-rich nuclei (with 86 <= A <= 209) that receive contribution only by slow neutron captures.