Total cross sections and thermonuclear reaction rates for ⁹Be(α,n)¹²C

The ⁹Be(α,n)¹²C reaction determines the rate for neutron-catalyzed helium burning and thus plays an important role in supernovae ejecta under α- and n-rich conditions which may lead to the r process. Cross sections for this reaction have been measured for 0.16≤E_c.m.≤1.87 MeV using a 4π neutron detector, and are used to calculate the thermonuclear reaction rates for temperatures between 0.1 and 10 GK. During these measurements, the thick-target yields were determined for 0.50≤E_α≤2.30 MeV, the stopping powers for α’s in beryllium determined for 0.24≤E_α≤2.12 MeV, and the ⁹Be(p,p) elastic scattering cross sections measured at θ_lab=142.4° for 2.34≤E_p≤2.66 MeV.