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

The short-lived nuclide Ti44 is an important nuclide for the understanding of explosive nucleosynthesis. The main production reaction, Ca40(α,γ)Ti44, 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 α-rich freeze-out during a core-collapse supernova has been covered entirely with a Ca40 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 Ti44 yield is higher than the one based on previous prompt γ-ray studies commonly used in supernova models. The presented new rate results in an increased Ti44 production in supernovae.