Differential cross sections have been measured for $\alpha$ particles from the reactions ${\mathrm{Be}}^9({\mathrm{Li}}^6, \alpha ){\mathrm{B}}^{11}$ and ${\mathrm{Be}}^9({\mathrm{Li}}^7, \alpha ){\mathrm{B}}^{12}$. These reactions have been studied for the ground states, the first seven excited states of ${\mathrm{B}}^{11}$, and the first four excited states of ${\mathrm{B}}^{12}$. Absolute cross sections have been measured by comparison with Rutherford scattering. The measurements have been carried out for laboratory bombarding energies from 3.3 to 3.75 Mev.

• Received 25 July 1961

DOI:https://doi.org/10.1103/PhysRev.124.1506