Experimental and theoretical multi-channel study of direct nuclear reactions: a tool to provide data driven information on neutrino-less double-beta decay

The search for neutrino-less double beta (0vbb) decay has attracted much interest in the last years due to the extraordinary consequences that could derive from its observation. The NUMEN project aims to provide experimental information on the nuclear matrix elements involved in the expression of 0vbb-decay half-life by measuring the cross-section of double charge exchange nuclear reactions. The experimental set-up to measure the zero-degrees double charge exchange nuclear reaction cross-section, including the K800 superconducting cyclotron and the MAGNEX magnetic spectrometer at the INFN - Laboratori Nazionali del Sud, in Catania, are described in the present thesis. The data-reduction and theoretical analysis performed during the PhD period are detailed in the present thesis. They involve the cases of the 18O + 12C, 18O + 76Se and 20Ne + 76Ge networks of quasi-elastic nuclear reactions at 15.3 AMeV incident energy. The advantages of the newly proposed multi-channel approach are applied to the NUMEN nuclear reaction data analysis. Regarding the 18O+12C data analysis, a unique comprehensive and coherent theoretical calculation able to describe the whole network of direct reactions using state-of-the-art nuclear structure and reaction theories is performed for the first time in this work. This holistic approach, applied both to the experimental and theoretical analysis, is the main feature and novelty of the work here presented. The experimental and theoretical analysis for the 76Ge <-> 76Se network of direct nuclear reactions, with a special attention to the elastic and inelastic scattering, single and double charge exchange reaction channels, is also carried out and described in detail.