Giant dipole emission in N/ Z asymmetric heavy-ion reactions.

We have measured the high-energy γ-ray spectra from the fusion reactions 130 MeVO +Mo and 240 MeVTi +Ni, populating theSn andSn compound nuclei at the excitation energy of 110 MeV. The comparison of the spectra shows a ~36% enhancement of the α-ray yield in the Giant Dipole Resonance region ( E > 8 MeV) when the O-induced reaction is considered. This enhancement is interpreted as due to entrance channel effects related to the N/ Z asymmetry between the target and the projectile. [ABSTRACT FROM AUTHOR]