  The 44Ti(t1/2 = 59 y) 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
44Ti production reaction, 40Ca(alpha,gamma)44Ti (E_cm = 0.6-1.2 MeV/u), by
direct off- line counting of 44Ti 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 44Ti yield by a
factor ~2 over previous estimates and bringing it closer to Cas A observations.
