The ${}_{}{}^9{}_{}{}^{}\mathrm{Be}$(α,n${)}^{12}$C 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≤${\mathit{E}}_{\mathrm{c}.\mathrm{m}.\mathrm{}}$≤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≤${\mathit{E}}_{\mathrm{\alpha }}$≤2.30 MeV, the stopping powers for α’s in beryllium determined for 0.24≤${\mathit{E}}_{\mathrm{\alpha }}$≤2.12 MeV, and the ${}_{}{}^9{}_{}{}^{}\mathrm{Be}$(p,p) elastic scattering cross sections measured at ${\mathrm{\theta }}_{\mathrm{lab}}$=142.4° for 2.34≤${\mathit{E}}_{\mathit{p}}$≤2.66 MeV.

• Received 30 August 1993

DOI:https://doi.org/10.1103/PhysRevC.49.1205