Astrophysical Reaction Rate for the Neutron-Generator Reaction<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mmultiscripts><mml:mi mathvariant="normal">C</mml:mi><mml:mprescripts/><mml:none/><mml:mn>13</mml:mn></mml:mmultiscripts><mml:mo stretchy="false">(</mml:mo><mml:mi>α</mml:mi><mml:mo>,</mml:mo><mml:mi>n</mml:mi><mml:mo stretchy="false">)</mml:mo><mml:mmultiscripts><mml:mi mathvariant="normal">O</mml:mi><mml:mprescripts/><mml:none/><mml:mn>16</mml:mn></mml:mmultiscripts></mml:math>in Asymptotic Giant Branch Stars

The reaction 13C(alpha,n) is considered to be the main source of neutrons for the s process in asymptotic giant branch stars. At low energies, the cross section is dominated by the 1/2+ 6.356 MeV subthreshold resonance in (17)O whose contribution at stellar temperatures is uncertain by a factor of 10. In this work, we performed the most precise determination of the low-energy astrophysical S factor using the indirect asymptotic normalization (ANC) technique. The alpha-particle ANC for the subthreshold state has been measured using the sub-Coulomb alpha-transfer reaction ((6)Li,d). Using the determined ANC, we calculated S(0), which turns out to be an order of magnitude smaller than in the nuclear astrophysics compilation of reaction rates.