Coherent and incoherent processes in projectile breakup

We have studied the breakup of 140 MeV 16 O into 12 C + α by targets of 12 C, 13 C and 28 Si. At least two mechanisms contribute. One can be identified as the coherent excitation of the 16 O projectile to components of the giant resonance states. Another dominant mechanism may be the quasi-free scattering of the α or 12 C constituents of the projectile by the target.