First accurate normalization of the -delayed decay of N and implications for the C(,)O astrophysical reaction rate

Kirsebom, O. S.*; Tengblad, O.*; Andreyev, A. N.; 41 of others*

The C(,)O reaction plays a central role in astrophysics, but its cross section at energies relevant for astrophysical applications is only poorly constrained by laboratory data. The reduced width, , of the bound 1 level in O is particularly important to determine the cross section. The magnitude of is determined via sub-Coulomb -transfer reactions or the -delayed decay of N, but the latter approach is presently hampered by the lack of sufficiently precise data on the -decay branching ratios. Here we report improved branching ratios for the bound 1 level () and for -delayed emission (). Our value for is 33 larger than previously held, leading to a substantial increase in . Our revised value for is in good agreement with the value obtained in -transfer studies and the weighted average of the two gives a robust and precise determination of , which provides significantly improved constraints on the C(,)O cross section in the energy range relevant to hydro static He burning.