40Ca(α,γ)44Ti reaction in the energy regime of supernova nucleosynthesis -: art. no. 041102

The Ti-44(t(1/2)=59 yr) nuclide, an important signature of supernova nucleosynthesis, has recently been observed as live radioactivity by gamma-ray astronomy from the Cas A remnant. We investigate in the laboratory the major Ti-44 production reaction Ca-40(alpha,gamma)Ti-44 (E-c.m.similar to 0.6-1.2 MeV/u) by direct off-line counting of Ti-44 nuclei. The yield, significantly higher than inferred from previous experiments, is analyzed in terms of a statistical model using microscopic nuclear inputs. The associated stellar rate has important astrophysical consequences, increasing the calculated supernova Ti-44 yield by a factor similar to 2 over previous estimates and bringing it closer to Cas A observations.