First inverse kinematics measurement of resonances in 7Be(α ,γ )11C 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 ν p 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 p p chains via the ⁷Be(α ,γ )¹¹C reaction has been identified as an important link which can influence the nuclear flow and, therefore, the efficiency of the ν p 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 ⁷Be(α ,γ )¹¹C reaction with previously unknown strengths using an intense radioactive ⁷Be beam from the Isotope Separator and Accelerator (ISAC-I) Center facility and the DRAGON recoil separator in inverse kinematics. We have decreased the ⁷Be(α ,γ )¹¹C reaction rate uncertainty to ≈9.4 -10.7 % over the relevant temperature region.