Measurements of Dynamical Dipole in isospin asymmetric fusion reactions

In heavy ion nuclear reactions the process leading to complete fusion is expected to produce pre-equilibrium gamma-ray emission, if particular conditions are met. Indeed, when there is an N/Z asymmetry between projectile and target, charge equilibration takes place with a collective dipole oscillation, called Dynamical Dipole (DD), associated to a gamma-ray emission. The existing experimental data concerning this pre-equilibrium gamma-ray emission are still rather scarce and manly concentrated in the A similar or equal to 132 mass region. The very preliminary results concerning the measurement of the DD gamma-ray emission in the fusion reaction O-16 (E-lab = 192 MeV) + Sn-116 at 12 MeV/u will be presented and compared with the gamma yield measured for the same reaction at 8.1 and 15.6 MeV/u. The present experiment aims at the measurement of the total emission yield of the DD at 12 MeV/u where the predicted theoretical yield does not completely reproduce the experimental data. The experiment has been performed at the INFN Legnaro Laboratories using the GARFIELD-HECTOR array.