Eur. Phys. J. A (2018) 54: 72
https://doi.org/10.1140/epja/i2018-12509-3

Review

The NUMEN project: NUclear Matrix Elements for Neutrinoless double beta decay

¹ Dipartimento di Fisica e Astronomia, Università di Catania, Catania, Italy
² Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud, Catania, Italy
³ Istituto Nazionale di Fisica Nucleare, Sezione di Catania, Catania, Italy
⁴ Instituto de Fisica, Universidade de Sao Paulo, Sao Paulo, Brazil
⁵ Istituto Nazionale di Fisica Nucleare, Sezione di Torino, Torino, Italy
⁶ Instituto de Física, Universidad Nacional Autónoma de México, México D.F., Mexico
⁷ School of Physics and Astronomy Tel Aviv University, Tel Aviv, Israel
⁸ Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, México D.F., Mexico
⁹ Akdeniz University, Antalya, Turkey
¹⁰ Departamento de FAMN, Universidad de Sevilla, Sevilla, Spain
¹¹ Instituto de Fisica, Universidade Federal Fluminense, Niteroi, Brazil
¹² Stony Brook University, Stony Brook, NY, USA
¹³ LPC Caen, Normandie Université, ENSICAEN, UNICAEN, CNRS/IN2P3, Caen, France
¹⁴ Istituto Nazionale di Fisica Nucleare, Sezione di Genova, Genova, Italy
¹⁵ Institute of Natural Science, Karadeniz Teknik Universitesi, Trabzon, Turkey
¹⁶ DISAT-Politecnico di Torino, Torino, Italy
¹⁷ Università degli Studi di Enna “Kore”, Enna, Italy
¹⁸ CNR-IMM, Sezione di Catania, Catania, Italy
¹⁹ University of Giessen, Giessen, Germany
²⁰ Instituto de Pesquisas Energeticas e Nucleares IPEN/CNEN, Sao Paulo, SP, Brazil
²¹ Department of Physics and HINP, The University of Ioannina, Ioannina, Greece
²² IFIN-HH, Bucarest, Romania
²³ Centro Universitario FEI, Sao Bernardo do Campo, Brazil
²⁴ Laboratory of Physical Chemistry, Department of Chemistry, National and Kapodistrian University of Athens, Athens, Greece
²⁵ Dipartimento di Fisica dell’Università di Genova, Genova, Italy

^* e-mail: cappuzzello@lns.infn.it

Received: 23 January 2018
Accepted: 10 April 2018
Published online: 8 May 2018

Abstract

The article describes the main achievements of the NUMEN project together with an updated and detailed overview of the related R&D activities and theoretical developments. NUMEN proposes an innovative technique to access the nuclear matrix elements entering the expression of the lifetime of the double beta decay by cross section measurements of heavy-ion induced Double Charge Exchange (DCE) reactions. Despite the fact that the two processes, namely neutrinoless double beta decay and DCE reactions, are triggered by the weak and strong interaction respectively, important analogies are suggested. The basic point is the coincidence of the initial and final state many-body wave functions in the two types of processes and the formal similarity of the transition operators. First experimental results obtained at the INFN-LNS laboratory for the ⁴⁰Ca(¹⁸O,¹⁸Ne)⁴⁰Ar reaction at 270MeV give an encouraging indication on the capability of the proposed technique to access relevant quantitative information. The main experimental tools for this project are the K800 Superconducting Cyclotron and MAGNEX spectrometer. The former is used for the acceleration of the required high resolution and low emittance heavy-ion beams and the latter is the 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 experimental resolution and sensitivity required for the accurate measurement of the DCE cross sections at forward angles. However, the tiny values of such cross sections and the resolution requirements demand beam intensities much larger than those manageable with the present facility. The on-going upgrade of the INFN-LNS facilities in this perspective is part of the NUMEN project and will be discussed in the article.