Experimental study of precisely selected evaporation chains in the decay of excited Mg25

Abstract

The reaction $^{12}\mathrm{C}+^{13}\mathrm{C}$ at $95\phantom{\rule{0.16em}{0ex}}\mathrm{MeV}$ 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 $^{25}\mathrm{Mg}$ aiming both at a new stringent test of the statistical description of nuclear decay and a direct comparison with the decay of the system $^{24}\mathrm{Mg}$ formed through $^{12}\mathrm{C}+^{12}\mathrm{C}$ 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 $^{24}\mathrm{Mg}$, we observed some deviations in the branching ratios, in particular for those chains involving only the evaporation of $\ensuremath{\alpha}$ particles. From this point of view the behavior of the $^{24}\mathrm{Mg}$ and $^{25}\mathrm{Mg}$ decay cases appear to be rather similar. An attempt to obtain a full mass balance even without neutron detection is also discussed.