Formation and deexcitation of the composite nucleus in the Ni+Al reaction at 28 A.MeV

The formation and the deexcitation of the composite nucleus formed during t he Ni + Al reaction at 28 A.MeV has been studied with the 4 pi multidetecto r AMPHORA. A rigourous selection of the experimental data is described in o rder to extract a central collision sample. Then different models are compa red to the data. The incomplete fusion process is in agreement with the dat a. The azimuthal angle correlations of He-Li and Li-Li pairs have been used to discriminate sequential or instantaneous emission. The sequential deexc itation is more consistent with all the data. The different analysis allow to describe all the characteristics of the compound nucleus and finally a f usion cross section of 300 +/- 100 mbarn has been measured.