The reaction $^{32}$S + $^{197}$Au near the interaction barrier
Résumé
The path to the synthesis of super heavy elements is strongly hindered by the competition between fusion and quasi-fission in heavy ions reactions at near barrier energies. We report on a recent experimental investigation performed at the ALTO facility of IPN Orsay, France on the heavy-ion collision around the Coulomb barrier of 32S+197Au. The fission-fragment mass and total kinetic energy were measured by the double arm mass spectrometer for binary fragments CORSET, using the double time of flight approach. The asymmetric structure on top of the predominant symmetric one may suggests the contribution from either quasi-fission or pre-equilibrium fission or might be driven by shell effects in the compound nucleus fission. To get further insight on such puzzling cases situated at the crossroads of the various opened channels, we extended the measurement to coincident prompt γ -rays, of low and high energy. For this purpose, the prompt γ-rays following fission were detected by the coupled high efficiency ORGAM array consisting of 10 Compton suppressed Germanium detectors (BGO shielded), located at backward angles and the first cluster of the future PARIS calorimeter consisting of 9 close packed phoswich detectors and another single phoswich, together covering a wide angular and energy range.