Production ofF18andNa24in Irradiations of Various Targets with Protons between 1 and 6 Bev

Cross sections are reported for the formation of ${\mathrm{Na}}^{24}$ and ${\mathrm{F}}^{18}$ in the interaction of Cu, Ag, Ta, Au, Pb, and U with protons of several energies between 1 and 6 Bev. The cross sections all increase with increasing energy. At each energy the cross sections go through a minimum when plotted against target mass number. The data are interpreted in terms of a spallation mechanism for Cu and Ag targets, with some contribution from fission especially in the case of Ag, and in terms of a fragmentation process for the heavy-element targets.