Mass, energy, and angular distribution data for fragments with $A\ge 6$ produced in intermediate-energy proton- and alpha-particle-induced reactions on ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ and ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ nuclei are compared with the results of an intranuclear cascade calculation followed by deexcitation of the residual nuclei via a Fermi breakup mechanism. In this latter step all possible particle-stable exit-channel states are included in the phase space available for decay. The shapes of the angular distributions are reproduced successfully by the calculation, even at relatively low bombarding energies (e.g., $E_{\alpha }=60\mathrm{}$ MeV). The energy spectra are also reproduced qualitatively. The isobaric cross sections of fragments heavier than the target nucleus are underpredicted for alpha-particle-induced reactions, whereas the yields of fragments with $A=6-8\mathrm{}$ are overpredicted. The former discrepancy is attributed to the importance of alpha-particle breakup during the cascade while the latter may serve as a measure of the relative importance of statistical multibody breakup mechanisms.

[NUCLEAR REACTIONS Intranuclear cascade, Fermi breakup model, evaporation model; calculated $\sigma (E,\theta ,A)$ for ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}(\alpha ,\mathrm{HI})$, ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$(p,HI), ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$(p,HI); HI: $A=6-19\mathrm{}$.]

• Received 22 August 1983

DOI:https://doi.org/10.1103/PhysRevC.29.1606