Pre-equilibriumαDecay inO16+Al27Collisions at 65 MeV

The mechanism of the reaction ${}_{}{}^{27}{}_{}{}^{}\mathrm{Al}({}_{}{}^{16}{}_{}{}^{}\mathrm{O}, {}_{}{}^{12}{}_{}{}^{}\mathrm{C}\alpha ){}_{}{}^{27}{}_{}{}^{}\mathrm{Al}$ at 65.6-MeV incident energy has been examined with use of coincidence techniques. It is shown that the broad bell-shaped peak observed in ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ singles spectra corresponds to an $\alpha$-transfer-like process leading to fixed excitation energy in the $\alpha$+${}_{}{}^{27}{}_{}{}^{}\mathrm{Al}$ system. The $\alpha$-${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ angular correlation, however, is forward-peaked along the momentum-transfer direction, suggesting that the decay time of the system is less than required for equilibration into ${}_{}{}^{31}{}_{}{}^{}\mathrm{P}$.