Total cross-section measurements for ^(14)(α, γ)18F

Abstract

Total cross section measurements have been made for the ^(14)N(α,γ)^(18)F reaction for 0.5 ≦ E_α ≦ 1.2 MeV. A new resonance has been found at E_α(lab) = 0.56 MeV, corresponding to the 4.849 MeV state in ^(18)F. The quantity (2J + 1)Γ_αΓ_γ/Γ was determined to be (2.79±0.5) × 10^(−4) eV and 0.108±0.015 eV for states at E_α = 0.56 and 1.14 MeV, respectively. From a theoretical calculation of the cross section for direct radiative capture and an extrapolation of the tails of the measured resonances to E_α = 0.0, a value S ≈ 0.7 MeV · b has been estimated for the non-resonant S-factor. The astrophysical significance of the ^(14)N(α,γ)^(18)F reaction is discussed and the reaction rate, N_A〈 σν 〉, is calculated for temperatures 0.01 ≦ T_9 ≦ 1.0. The rate is accurately determined by the experimental measurements for T_9 > 0.09.