Breakout from the hot CNO cycle via the18Ne(α,p)21Nareaction

The reaction ${}^{18}\mathrm{Ne}(\alpha {,p)}^{21}\mathrm{Na},$ of importance to nuclear astrophysics, has been studied directly using the postaccelerated radioactive ${}^{18}\mathrm{Ne}$ beam available at Louvain-la-Neuve and a gaseous helium target. This study covered the energy region from 2.04 to 3.01 MeV in the center of mass, and identified various levels in the compound nucleus ${}^{22}\mathrm{Mg}.$ The stellar reaction rate due to these states has been deduced. The experimental rate shows good agreement with theoretical predictions [J. Görres, M. Wiescher, and F. K. Thielemann, Phys. Rev. C 51, 392 (1995)] above 2.5 GK.