First direct measurement of the C 11 (α,p) N 14 stellar reaction by an extended thick-target method

The C11(α,p)14N reaction is an important α-induced reaction competing with β-limited hydrogen-burning processes in high-temperature explosive stars. We directly measured its reaction cross sections both for the ground-state transition (α,p0) and the excited-state transitions (α,p1) and (α,p2) at relevant stellar energies 1.3-4.5 MeV by an extended thick-target method featuring time of flight for the first time. We revised the reaction rate by numerical integration including the (α,p1) and (α,p2) contributions and also low-lying resonances of (α,p0) using both the present and the previous experimental data which were totally neglected in the previous compilation works. The present total reaction rate lies between the previous (α,p0) rate and the total rate of the Hauser-Feshbach statistical model calculation, which is consistent with the relevant explosive hydrogen-burning scenarios such as the νp process.