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 the Ni+Al reaction at 28 A.MeV has been studied with the 4 π multidetector AMPHORA. A rigorous selection of the experimental data is described in order to extract a central collision sample. Then different models are compared to the data. The incomplete fusion process is in agreement with the data. The azimuthal angle correlations of He-Li and Li-Li pairs have been used to discriminate sequential or instantaneous emission. The sequential deexcitation is more consistent with all the data. The different analyses allow to describe all the characteristics of the compound nucleus and finally a fusion cross section of 300±100 mbarn has been measured. (orig.)