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42nd Symposium on Nuclear Physics (SNP), Cocoyoc, Mexico, 7 - 10 January 2019
An updated overview of recent results on Heavy-Ion induced reactions of interest for neutrinoless double beta decay is reported in the framework of the NUMEN project. The NUMEN idea is to study heavy-ion induced Double Charge Exchange (DCE) reactions with the aim to get information on the nuclear matrix elements for neutrinoless double beta (0v ss ss) decay. Moreover, to infer the neutrino average masses from the possible measurement of the half- life of 0v ss ss decay, the knowledge of the nuclear matrix elements is a crucial aspect.guarantees the above mentioned performance and its relevance in the research for heavy-ion physics [8-10], also taking advantage of its coupling to the EDEN neutron detector array [ 11,12]. The Ca-40(O-18,Ne-18)Ar-40 reaction was studied at 15 MeV/u, showing that high mass, angular and energy resolution energy spectra and accurate absolute cross sections are at our reach, even at very forward angles, see ref. [13]. In addition, a schematic analysis of the reaction cross sections demonstrated that relevant quantitative information on DCE matrix elements can be extracted from the data. This result demonstrated that the previous experimental limitations are almost overcome and that high resolution and statistically significant experimental data can be measured for DCE processes. In the present experimental conditions, due to the limitation arising from the tiny cross-sections of the processes of interest, only very few systems can be measured within the 5-years project. In order to systematically explore all the nuclei candidates for 0v ss ss, a beam intensity at least two orders of magnitude higher than the present must be achieved. The NUMEN project is conceived in a long-range time perspective, in view of a comprehensive study of many candidate systems for 0v ss ss decay. Moreover, the project promotes a renewal of the INFN-LNS research infrastructure [14] with a specific R&D activity on detectors, materials and instrumentation. As a consequence, major upgrades of the detector technologies (3D ion tracker, particle-identification wall, gamma-ray array,...) must be developed [15, 20]. Also the target technology must be upgraded, to avoid the damage of the thin films due to the high temperature involved [21, 23]. Moreover, a deep and complete investigation of the theoretical aspects connecting nuclear reaction mechanisms and nuclear matrix elements must be carried out [ 24, 26].