First inverse kinematics measurement of resonances in Be7(α,γ)C11 relevant to neutrino-driven wind nucleosynthesis using DRAGON

A possible mechanism to explain the origin of the light p nuclei in the Galaxy is the nucleosynthesis in the proton-rich neutrino-driven wind ejecta of core-collapse supernovas via the νp process. However, this production scenario is very sensitive to the underlying supernova dynamics and the nuclear physics input. As far as the nuclear uncertainties are concerned, the breakout from the pp chains via the Be7(α,γ)C11 reaction has been identified as an important link which can influence the nuclear flow and, therefore, the efficiency of the νp process. However, its reaction rate is poorly known over the relevant temperature range, T = 1.5–3 GK. We report on the first direct measurement of two resonances of the Be7(α,γ)C11 reaction with previously unknown strengths using an intense radioactive Be7 beam from the Isotope Separator and Accelerator (ISAC-I) Center facility and the DRAGON recoil separator in inverse kinematics. We have decreased the Be7(α,γ)C11 reaction rate uncertainty to ≈9.4–10.7% over the relevant temperature region.