The NUMEN Project: An Update of the Facility Toward the Future Experimental Campaigns

F Cappuzzello ,Salvatore Calabrese,Carlo Ferraresi,Diego Sartirana,L Neri ,G A Brischetto ,P Finocchiaro ,O Sgouros ,H Petrascu ,F Delaunay ,M Moralles ,D Calvo ,L Calabretta ,A Spatafora ,H Djapo ,A Russo ,V Soukeras ,D Torresi ,F Iazzi ,M Cavallaro ,L Pandola ,F Pinna ,L Campajola ,L Acosta ,C Agodi ,D Carbone ,S Tudisco ,I Boztosun ,J R B Oliveira ,E Chávez ,M Fisichella ,V Capirossi ,S O Solakcı ,Elisa Maria Gandolfo ,I Ciraldo ,Aydın Yıldırım

doi:10.3389/fspas.2021.668587

Abstract

The goal of NUMEN project is to access experimentally driven information on Nuclear Matrix Elements (NME) involved in the neutrinoless double beta decay (0νββ) by accurate measurements of the cross sections of heavy-ion induced double charge-exchange reactions. In particular, the (18O,18Ne) and (20Ne,20O) reactions are adopted as tools for β+β+and β−β−decays, respectively. The experiments are performed at INFN–Laboratory Nazionali del Sud (LNS) in Catania using the Superconducting Cyclotron to accelerate the beams and the MAGNEX magnetic spectrometer to detect the reaction products. The measured cross sections are very low, limiting the present exploration to few selected isotopes of interest in the context of typically low-yield experimental runs. In order to make feasible a systematic study of all the candidate nuclei, a major upgrade of the LNS facility is foreseen to increase the experimental yield by more than two orders of magnitude. To this purpose, frontier technologies are being developed for both the accelerator and the detection systems. An update description of the NUMEN project is presented here, focusing on recent achievements from the R&amp;D activity.

Highlights

Neutrinoless double beta decay (0νββ) is a nuclear process where a parent nucleus decays into a daughter isobar differing by two units of charge and two electrons are emitted
The results indicate that cross sections as low as 1 nb, can be measured with uncertainties of the order of 10%, using a beam intensity of the order of 1012 beam particles per second on typical targets with tenths of mg/cm2 surface density in month-long experiments
The data analysis is ongoing, with preliminary results showing that accurate Double Charge-Exchange (DCE) cross sections measurements can be extracted at very forward angles for the ground-to-ground state transitions

Summary

INTRODUCTION

Neutrinoless double beta decay (0νββ) is a nuclear process where a parent nucleus decays into a daughter isobar differing by two units of charge and two electrons (or positrons) are emitted. The aim of the NUMEN project is to measure the absolute cross section for heavy-ion induced DCE reactions on nuclei candidates for the 0νββ decay and find a connection between the NMEs of the two processes. In Cappuzzello et al (2015b) the 40Ca(18O,18Ne)40Ar reaction was studied at 15 MeV/u at the MAGNEX facility of INFN-LNS laboratory (Cappuzzello et al, 2016), showing that high mass, angular and energy resolution energy spectra and accurate absolute cross sections can be measured, even at very forward scattering angles With respect to this pilot experiment, additional difficulties are foreseen for the exploration of DCE on nuclei of interest for 0νββ research. The energy loss measured by the multiplication wires and the residual energy at the silicon

Experimental Setup

A New Scattering Chamber

Findings

CONCLUSION AND PERSPECTIVES