The Yield of Alpha-Particles from Beryllium Bombarded by Protons

Experiments to determine the excitation function of the reaction ${}_4{}^{}{}_{}{}^{}\mathrm{Be}_{}^9{}_{}{}^{}(p, \alpha ){}_3{}^{}{}_{}{}^{}\mathrm{Li}_{}^6{}_{}{}^{}$ for proton energies up to 400 kv are reported. It is shown that the yield is very large, $\mathrm{ca}$. 4×${10}^{-6\mathrm{}}$ alphaparticle per proton at 400 kv, but the derived thin target curve shows a marked flattening from the exponential form observed at lower voltages. The cross section is nearly constant above 300 kv, and has a value of about 2.3×${10}^{-25\mathrm{}}$ ${\mathrm{cm}}^2$.