Measurement of the Ca40(α,γ)Ti44 reaction relevant for supernova nucleosynthesis

The short-lived nuclide Ti-44 is an important nuclide for the understanding of explosive nucleosynthesis. The main production reaction, Ca-40(alpha,gamma)Ti-44, has been studied in inverse kinematics with the recoil mass spectrometer DRAGON located at the TRIUMF-ISAC facility in Vancouver, Canada. The temperature range relevant for alpha-rich freeze-out during a core-collapse supernova has been covered entirely with a Ca-40 beam of 0.60 to 1.15 MeV/nucleon. All relevant quantities for the calculation of the astrophysical reaction rate have been measured directly. Because of many previously undiscovered resonances, the reaction rate derived from the energy dependent Ti-44 yield is higher than the one based on previous prompt gamma-ray studies commonly used in supernova models. The presented new rate results in an increased Ti-44 production in supernovae.