Formation ofN13in High-Energy Nuclear Reactions

Experimental cross sections are reported for the formation of ${\mathrm{N}}^{13}$ in the bombardment of Zn, In, Pb, and $U$ with protons of 1.0, 1.9, and 2.9 Bev energy. These values are compared with theoretical ${\mathrm{N}}^{13}$ emission cross sections for protons energies of 0.84 and 1.84 Bev. The calculations are based on the evaporation model. The previously described Monte Carlo procedure was modified in order to obtain better statistical accuracy for the calculated ${\mathrm{N}}^{13}$ cross sections. Previously computed emission cross sections for ${\mathrm{He}}^6$, ${\mathrm{Li}}^8$, and ${\mathrm{Be}}^7$ were also recomputed using the modified Monte Carlo procedure. The cross sections were computed for three different formulations of the interaction radius. Good fit with the experimental ${\mathrm{He}}^6$, ${\mathrm{Li}}^8$, and ${\mathrm{Be}}^7$ cross sections is obtained when the smaller values for the interaction radius are used. However, the fit with the experimental ${\mathrm{N}}^{13}$ values is not good enough to exclude processes other than evaporation as contributing to the experimentally observed cross sections.