The S[sub E1] factor of the [sup 12]C(α,γ)[sup 16]O Reaction and the [sup 16]N β-delayed α Decay

The 12C(α,γ)16O reaction is of great importance for the understanding the nuclear synthesis and explosion mechanism of the supernova. The cross section at the relevant stellar burning energies, around 300 keV, is dominated by the sub‐threshold resonances. The 16N β‐delayed α decay data provide the most sensitive constrain on this sub‐threshold resonance. Using twin‐ionization chambers, we have measured the α particles and 12C recoil nuclei in coincidence. The spectrum has been fitted together with the published 12C(α,γ)16O data and the elastic scattering phase shift data using R‐matrix. The SE1 factor at 300 keV has been determined as 73±21 keVb.