Nuclear astrophysics at ISAC with DRAGON: Initial studies

The new DRAGON recoil separator facility, designed and built to measure directly the rates of radiative proton and alpha capture reactions important for nuclear astrophysics, is now in operation at the TRIUMF-ISAC radioactive beams facility in Vancouver, Canada. Experiments have been conducted for the first time on the 21Na(p,γ)22Mg reaction. The evolution of nova explosions, and particularly their 22Na abundance, depends sensitively on this reaction rate. Commissioning studies using the well-known stable beam reactions 21Ne(p,γ)22Na, 20Ne(p,γ)21Na, and 24Mg(p,γ)25Al have shown that the recoil separator performs within its design specifications both in suppression power and acceptance. The first radioactive beam studies were done using a beam of 5 × 10821Na atoms/s. Yield measurements recording simultaneously singles and coincident heavy-ion and gamma signals were performed, scanning in energy over the known resonance reported previously in 22Mg at Ecm = 212 keV, and in addition, over a strong resonance observed at Ecm ≈822 keV.