New determination of the astrophysical S factor SE1 of the 12C(α,γ)16O reaction

A new measurement of the beta-delayed alpha decay of N-16 has been performed using a set of high efficiency ionization chambers. Sources were made by implantation of a N-16 beam, yielding very clean alpha spectra down to energies as low as 400 keV. Our data are in good agreement with earlier results. For the S factor S-E1, we obtain a value of 74 +/- 21 keV b. In spite of improvements in the measurement, the error in S-E1 remains relatively large because of the correlations among the fit parameters and the uncertainties inherent to the extrapolation.