13C(α,n)16O is the main neutron source reaction of slow neutron capture (s) process in asymptotic giant branch (AGB) stars. The 6.356 MeV 1/2+ subthreshold resonance in 17O plays an important role in the 13C(α,n)16O reaction. The 13C(11B, 7Li)17O angular distributions were measured using HI-13 tandem accelerator and Q3D magnetic spectrograph, and then used to determine the α-width of the subthreshold resonant state which is currently the most uncertain parameter for determining the 13C(α,n)16O reaction rate. By using the present α-width, the astrophysical S-factor and the stellar rate of the 13C(α,n)16O reaction were derived. This shed some light on the existing discrepancies up to a factor of 25 in S-factors derived from different authors. The simulation of s-process in AGB stars shows that the new reaction rate produces 25% more Pb than the CF88 compilation.
- AGB stars
- Angular distribution of transfer reaction
- Astrophysical S-factor
- Subthreshold resonance