Inclusive cross sections for the ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$${+}^{40}$Ca reaction leading to fission-like fragments with mass 20≤$A_{\mathrm{fragment}\mathrm{\le }}$28, and for the ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$${+}^{44}$Ca reaction with 20≤$A_{\mathrm{fragment}\mathrm{\le }}$30, have been determined by measurements at seven energies with 69.3≤$E_{\mathrm{lab}{(\mathrm{}}^{16}}$O)≤87.3 MeV and for 30°≤${\mathrm{theta}}_{\mathrm{lab}\mathrm{\le }60\mathrm{°}}$. The evaporation-residue cross sections were also measured over a limited angular range at the same energies to search for any gross difference between these cross sections for the two systems. No difference was detected outside the experimental uncertainties. The resulting energy spectra and mass distributions for the fission-like yields are shown to be consistent with a fusion-fission reaction mechanism. Although it was not possible to determine the total fission-like cross sections since the apparent mass range of the fission-like yields was greater than that covered by the experiment, the magnitude and energy dependence of the observed fission-like cross sections, as compared to the evaporation-residue cross sections, are also found to be consistent with a fusion-fission mechanism.

• Received 21 July 1986

DOI:https://doi.org/10.1103/PhysRevC.34.1746