The β-delayed α spectrum of 16N and the low-energy extrapolation of the 12C(α,γ)16O cross section

The low-energy part of the βα-decay spectrum of 16N permits the determination of the reduced α-width θα2 of the 7.12 MeV subthreshold state of 16O, which dominates the low-energy p-wave capture amplitude of the astrophysically important reaction 12C(α,γ)16O. In a first run, a total of 7.1 x 103 α particles from the decay of 16N nuclei, selected by the TRIUMF isotope separator TISOL, have been observed in a 10.6 μm detector in coincidence with the recoiling 12C nuclei in a second detector, thus removing most sources of low-energy α background. (Author)