Study of the 7Be(α,γ)11C reaction with DRAGON for vp–process nucleosynthesis

The production of the p–nuclei is one of the unsolved puzzles in nuclear astrophysics. A possible mechanism is the nucleosynthesis in the neutrino–driven winds of core–collapse supernovae (νp–process), but it carries uncertainties, mostly in the supernova dynamics and the nuclear physics input. The pp-chain breakout reaction 7Be(α,γ)11C, which occurs prior to the supernova explosion, was identified as an important link which can influence the nuclear flow of the z/p-process and the final abundances of the p-nuclei. Nevertheless, its reaction rate is poorly known over the relevant energy range (T=1.5-3 GK). To improve the 7Be(α,γ)11C rate for vp-process nucleosynthesis temperatures, the first measurement of the strengths of two important resonances with unknown strength was recently performed at TRIUMF. A radioactive 7Be beam (t1/2 = 53.24 d) beam and the DRAGON recoil separator were used. The experimental details and preliminary results for the resonance strengths will be discussed.