New measurement of the α asymptotic normalization coefficient of the 1/2+ state in 17O at 6.356 MeV that dominates the 13C(α, n)16O reaction rate at temperatures relevant for the s process

Background: Accurate knowledge of the C-13(alpha, n)O-16 reaction cross section is important for the understanding of the s process in asymptotic giant branch stars, since it is considered to be the main source of neutrons. The subthreshold 1/2(+) state at excitation energy of 6.356 MeV in O-17 has a strong influence on the reaction cross section at energies relevant for astrophysics. Several experiments have been performed to determine the contribution of this state to the C-13(alpha, n)(16)Oreaction rate. Nevertheless, significant discrepancies between different measurements remain. Purpose: The aim of this work is to investigate these discrepancies. Method: An 8 MeV 13C beam (below the Coulomb barrier) was used to study the alpha-transfer reaction Li-6(C-13, d)O-17. Results: The squared Coulomb-modified asymptotic normalization coefficient of the 1/2+ state in 17O measured in this work is ((C) over tildeC(alpha-13C)(17O(1/2+)) = 3.6 +/- 0.7 fm(-1). Conclusions: Discrepancy between the results of a-transfer experiments have been resolved. However, some discrepancy with the most recent measurement using the Trojan Horse method remains.