NUMEN Determining the Nuclear Matrix Elements of Neutrinoless Double Beta Decays by Heavy-Ion Double Charge Exchange Reactions Proponents: C. Agodi, X. Aslanouglou, F. Balestra, R. Bijker, D. Bonanno, T. Borello, V. Branchina, L. Calabretta, A. Calanna, F. Cappuzzello, D. Carbone, M. Cavallaro, D. Calvo, M. Colonna, G. D’Agostino, N. Deshmuk, P. N. de Faria, A. Ferrero, A. Foti, P. Finocchiaro, P. R. S. Gomes, V. Greco, G. Lanzalone, R. Linares, J. Lubian, F. Iazzi, R. Introzzi, A. Lavagno, D. Lo Presti, N. Medina, D. R. Mendes, A. Muoio, J. R. B. Oliveira, A. Pakou, L. Pandola, D. Rifuggiato, M. R. D. Rodrigues, G. Santagati, E. Santopinto, L. Scaltrito, O. Sgouros, V. Soukeras, S. Tudisco, R. I. M. Vsevolodovna, V. Zagatto Spokespersons: C. Agodi and F. Cappuzzello Istituto Nazionale di Fisica Nucleare - Laboratori Nazionali del Sud, Catania, Italy Istituto Nazionale di Fisica Nucleare - Sezioni di Catania, Torino, Genova, Italy Dipartimento di Fisica e Astronomia, Università di Catania, Italy Università degli Studi di Enna "Kore", Enna, Italy Università degli Studi di Messina, Messina, Italy Politecnico di Torino, Italy Instituto de Fisica da Universidade De Sao Paulo, Brazil Instituto de Fisica da Universidade Federal Fluminense, Niteroi, Brazil Department of Physics and HINP, The University of Ioannina, Ioannina, Greece Abstract: An innovative technique to access the nuclear matrix elements entering the expression of the life time of the double beta decay by relevant cross sections of double charge exchange reactions is proposed. The basic point is the coincidence of the initial and final state wave-functions in the two classes of processes and the similarity of the transition operators, which in both cases present a superposition of Fermi, Gamow-Teller and rank-two tensor components with a relevant implicit momentum transfer. First pioneering experimental results obtained at the INFN-LNS laboratory for the 40Ca(18O,18Ne)40Ar reaction at 270 MeV, give encouraging indication on the capability of the proposed technique to access relevant quantitative information. A key aspect of the project is the use of the K800 Superconducting Cyclotron (CS) for the acceleration of the required high resolution and low emittance heavy-ion beams and of the MAGNEX large acceptance magnetic spectrometer for the detection of the ejectiles. The use of the high-order trajectory reconstruction technique, implemented in MAGNEX, allows to reach the high mass, angular and energy resolution required even at very low cross section. The LNS set-up is today an ideal one for this research even at a worldwide perspective. However a main limitation on the beam current delivered by the accelerator and the maximum rate accepted by the MAGNEX focal plane detector must be sensibly overcome in order to systematically provide accurate numbers to the neutrino physics community in all the studied cases. The upgrade of the LNS facilities in this view is part of this project. 1

The recent NUMEN workshop "Challenges in the investigation of double charge-exchange nuclear reactions: towards neutrino-less double beta decay" 2 List of speakers: N. Auerback Tel Aviv University (Israel) R. Broglia Università di Milano (Italy) and Niels Bohr Inst., Copenhagen (Denmark) O. Civitarese Dept. Phys., University of La Plata, Buenos Aires (Argentina) H. Ejiri RCNP, Osaka University (Japan) A. Faessler University of Tuebingen (Germany) D. Frekers University of Muenster (Germany) M. Horoi Dept. Phys., Central Michigan University (USA) J. Kotila Dept. Phys., University of Jyvaskyla (Finland) F. La Via CNR - IMM (Italy) D. Lo Presti INFN - Catania (Italy) L.Calabretta INFN - LNS (Italy) H. Lenske University of Giessen (Germany) G. Potel Lawrence Livermore National Laboratory (USA) M. Takaki Center for Nuclear Study, Univ. of Tokyo (Japan) K. Zuber Technische Universität Dresden (Germany) agenda.infn.it/event/NUMEN2015 Organizing Committee: C. Agodi F. Cappuzzello D. Carbone M. Cavallaro M. Colonna V. Greco F. Iachello L. Pandola S. Tudisco More than 80 worldwide participants Researchers for all the communities (INFN GR ) Alive discussions New collaborations for NUMEN Decisive step on the theoretical side Chairs: C. Agodi, F.Cappuzzello, M. Colonna

NUMEN workshop 1-2 December 2015 INFN, Laboratori Nazionali del Sud, Catania (Italy) The first NUMEN workshop LNS December 1-2, The meeting was conceived as an occasion to bring together the community involved in structure and reaction studies related to charge-exchange mechanisms and experts of neutrino physics, weak interaction and \beta decay, both from the experimental and theoretical points of view. This program was very well received at an international level ad almost 80 scientists have taken part in the event. It is worth noting that among the participants were researchers from the five INFN research groups. The meeting has offered the possibility to define the state of the art of the experimental and theoretical activities focused, on one side, on the study of charge exchange nuclear reactions and competitive processes and, on the other side, on the search for neutrino-less double \beta decay. The bridge between the two classes of events was underlined in almost all talks, in perfect sinergy with the spirit of the workshop. The meeting has put the bases for future collaborations and several hints have emerged about good strategies to be followed in order to support and to help the realization of the NUMEN project, at the theoretical, experimental and technological levels. 3

LNS PAC report