Experimental study of precisely selected evaporation chains in the decay of excited $^{25}$Mg
Résumé
The reaction C12+C13 at 95MeV bombarding energy is studied using the Garfield + Ring Counter apparatus located at the INFN Laboratori Nazionali di Legnaro. In this paper we want to investigate the de-excitation of Mg25 aiming both at a new stringent test of the statistical description of nuclear decay and a direct comparison with the decay of the system Mg24 formed through C12+C12 reactions previously studied. Thanks to the large acceptance of the detector and to its good fragment identification capabilities, we could apply stringent selections on fusion-evaporation events, requiring their completeness in charge. The main decay features of the evaporation residues and of the emitted light particles are overall well described by a pure statistical model; however, as for the case of the previously studied Mg24, we observed some deviations in the branching ratios, in particular for those chains involving only the evaporation of α particles. From this point of view the behavior of the Mg24 and Mg25 decay cases appear to be rather similar. An attempt to obtain a full mass balance even without neutron detection is also discussed.