The binary decay into strongly damped fragments and the quasielastic reactions of the ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$+ ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ system were measured at $E_{\mathrm{lab}}=107.5\mathrm{} \mathrm{and} 139.0$ MeV in the angular range of $30°<~{\theta }_{\mathrm{c}.\mathrm{m}.\mathrm{}}<~150°$ using kinematic coincidence. The loss in the binary decay cross section due to light particle evaporation by the highly excited fragments was evaluated. The $Q$-value-integrated angular distributions of the primary decay exhibit the $\frac{1}{{sin\theta }_{\mathrm{c}.\mathrm{m}.\mathrm{}}}$ behavior at backward angles, indicating a long lifetime. Mass distributions and the ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$/${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ ratio suggest a noncompound process for the reaction mechanism. Coupled-channels calculations, including a great number of channels populated in the reactions, yield good agreement with the experimental angular distributions.

• Received 3 August 1995

DOI:https://doi.org/10.1103/PhysRevC.53.2926