Measurement of the 40Ca(α, γ)44Ti reaction relevant for supernova nucleosynthesis

The short-lived nuclide 44 Ti is an important nuclide for the understanding of explosive nucleosynthesis. The main production reaction, 40 Ca(α, γ) 44 Ti, 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 40 Ca 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 44 Ti 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 44 Ti production in supemovae.

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