Use of the facility EXOTIC for fusion–evaporation studies

The EXOTIC facility was developed to produce light radioactive beams and it is installed at Laboratori Nazionali di Legnaro (LNL) of INFN. We have explored the capabilities of EXOTIC as a beam separator for studies of heavy ion fusion–evaporation reactions. For this purpose, the facility has been slightly modified to allow the detection and identification of the fusion–evaporation residues (ER). We have measured fusion reactions for the two systems ³²S $+$ ⁴⁸Ca and ³²S $+$ ⁶⁴Ni where the cross sections are known from previous experiments at LNL. The ion optical parameters of EXOTIC have been set to maximize the ER yield in the detector system for the various cases. A good and clean separation of the ER from beam-like particles was obtained in the experimental Energy–Time of Flight correlation plots. These encouraging results have been compared with the performance of the electrostatic deflector set-up PISOLO, routinely used at LNL for sub-barrier fusion experiments. The beam rejection factor of EXOTIC at 0°is comparable to the one of PISOLO at 2°–3°, while a gain of overall efficiency up to a factor 3 has been obtained with EXOTIC. We briefly discuss possible ways of improving these results.