Cross Section for Formation ofBe7by 20-155-MeV Proton-Induced Reactions in Carbon

The cross section for the reaction ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}(p, x){}_{}{}^7{}_{}{}^{}\mathrm{Be}$ was measured as a function of energy from 20 to 155 MeV. A sharp rise above the neighboring thresholds for ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}(p, {}_{}{}^6{}_{}{}^{}\mathrm{Li})$, ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}(p, \alpha d)$, and ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}(p, \alpha pn)$ reactions was observed. The excitation function peaks with a cross section of ∼20 mb at 40 MeV and then decreases slowly with increasing energy. No structure is observed at the thresholds for the ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}(p, tdp)$, ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}(p, 3d)$, or other reactions of higher threshold energy.