Cross-section measurements and thermonuclear reaction rates for 50Ti(p, γ)51V and 50Ti(p,n)50V

The yields of γ-rays from the reactions ⁵⁰Ti(p, γ)⁵¹V and ⁵⁰Ti(p, p 'γ)⁵⁰Ti have been measured as a function of bombarding energy over the range 0.73–4.39 MeV and the yield of neutrons from the reaction ⁵⁰Ti(p, n)⁵⁰V has been measured from threshold to a bombarding energy of 4.39 MeV. Competition effects were observed in the γ-ray yields from the (p, γ) and (p, pγ) reactions at the threshold of the (p, n) reaction. The observed yields in all channels were lower by factors of order 3 than those predicted by statistical-model calculations based on global optical parameters and the competition observed in the (p, γ) yield at the opening of the neutron channel was approximately one half that predicted by the statistical-model calculations. These failures of the calculations are tentatively attributed to the neutron closed-shell nature of ⁵⁰Ti. Thermonuclear reaction rates for the (p, γ) and (p, n) reactions are calculated for the temperature range (0.6–5) × 10⁹ K which includes the range of temperatures of interest in nucleosynthesis calculations.