The formation cross sections of ${\mathrm{Li}}^9$, ${\mathrm{C}}^{16}$, and ${\mathrm{N}}^{17}$ from B, C, ${\mathrm{N}}^{14}$, ${\mathrm{N}}^{15}$, ${\mathrm{O}}^{16}$, ${\mathrm{O}}^{18}$, F, Ne, Na, Mg, and Al targets bombarded with 156-MeV protons were measured by means of their neutron emission. The results were compared with calculations based on the two-step spallation mechanism. Certain reactions were shown to provide direct comparison with prompt cascade calculation. In general, the agreement between theory and experiment was good, and it is suggested that some discrepancies are attributable to the neglect of the effect of nuclear structure in the calculations. The importance of $\alpha$ emission in determining the pattern of spallation product cross section was demonstrated.

• Received 6 November 1967

DOI:https://doi.org/10.1103/PhysRev.169.836