# Recent results on heavy-ion induced reactions of interest for neutrinoless double beta decay at INFN-LNS

F. Cappuzzello, C. Agodi, L. Acosta, C. Altana, P. Amador-Valenzuela, N.

Auerbach, J. Barea, J. Bellone, R. Bijker, D. Bonanno, et al.

## ► To cite this version:

F. Cappuzzello, C. Agodi, L. Acosta, C. Altana, P. Amador-Valenzuela, et al., Recent results on heavy-ion induced reactions of interest for neutrinoless double beta decay at INFN-LNS. 27th International Nuclear Physics Conference, Jul 2019, Glasgow, United Kingdom. pp.012074, 10.1088/1742-6596/1643/1/012074. [hal-03400829](https://hal.science/hal-03400829)

HAL Id: hal-03400829

https://hal.science/hal-03400829

Submitted on 30 May 2024

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# Recent results on heavy-ion induced reactions of interest for neutrinoless double beta decay at INFN-LNS

F. Cappuzzello, C. Agodi, L. Acosta, C. Altana, P. Amador-Valenzuela, N.

Auerbach, J. Barea, J. Bellone, R. Bijker, D. Bonanno, et al.

## ► To cite this version:

F. Cappuzzello, C. Agodi, L. Acosta, C. Altana, P. Amador-Valenzuela, et al., Recent results on heavy-ion induced reactions of interest for neutrinoless double beta decay at INFN-LNS. 27th International Nuclear Physics Conference, Jul 2019, Glasgow, United Kingdom. pp.012074, 10.1088/1742-6596/1643/1/012074. [hal-03400829](https://hal.science/hal-03400829v1)

HAL Id: hal-03400829

https://hal.science/hal-03400829v1

Submitted on 30 May 2024

HAL is a multi-disciplinary open access
archive for the deposit and dissemination of sci-
entific research documents, whether they are pub-
lished or not. The documents may come from
teaching and research institutions in France or
abroad, or from public or private research centers.

L'archive ouverte pluridisciplinaire HAL, est
destinée au dépôt et à la diffusion de documents
scientifiques de niveau recherche, publiés ou non,
émanant des établissements d'enseignement et de
recherche français ou étrangers, des laboratoires
publics ou privés.

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Distributed under a Creative Commons Attribution 4.0 International License
PAPER • OPEN ACCESS

# Recent results on heavy-ion induced reactions of interest for neutrinoless double beta decay at INFN-LNS

To cite this article: F. Cappuzzello et al 2020 J. Phys.: Conf. Ser. 1643 012074

View the [article online](#) for updates and enhancements.

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PAPER • OPEN ACCESS

# Recent results on heavy-ion induced reactions of interest for neutrinoless double beta decay at INFN-LNS

To cite this article: F. Cappuzzello et al 2020 J. Phys.: Conf. Ser. 1643 012074

View the [article online](#) for updates and enhancements.

You may also like

- New spectrometer projects for challenging particle-gamma measurements of nuclear reactions
J R B Oliveira, P Finocchiaro, C Agodi et al.

- Search for Ultra-high-energy Photons from Gravitational Wave Sources with the Pierre Auger Observatory
A. Abdul Halim, P. Abreu, M. Aglietta et al.

- Recent results on heavy-ion direct reactions of interest for 0 decay at INFN - LNS
M. Cavallaro, L. Acosta, P. Adsley et al.

<figure><img src="image_2.png" /></figure>

The
Electrochemical
Society

Advancing solid state &
electrochemical science & technology

<figure><img src="image_3.png" /></figure>

DISCOVER
how sustainability
intersects with
electrochemistry & solid
state science research

<figure><img src="image_4.png" /></figure>
Recent results on heavy-ion induced reactions of interest for neutrinoless double beta decay at INFN-LNS

F. Cappuzzello<sup>1,2, (a)</sup>, C. Agodi<sup>1</sup>, L. Acosta<sup>13</sup>, C. Altana<sup>1</sup>, P. Amador-Valenzuela<sup>27</sup>, N. Auerbach<sup>17</sup>, J. Barea<sup>31</sup>, J. Bellone<sup>1,2</sup>, R. Bijker<sup>28</sup>, D. Bonanno<sup>3</sup>, T. Borello-Lewin<sup>9</sup>, I. Boztosun<sup>16</sup>, V. Branchina<sup>3</sup>, S. Brasolin<sup>4</sup>, G. Brischetto<sup>1,2,34</sup>, O. Brunasso<sup>4</sup>, S. Burrello<sup>1,20</sup>, S. Calabrese<sup>1,2</sup>, L. Calabretta<sup>1</sup>, D. Calvo<sup>4</sup>, V. Capirossi<sup>4,6</sup>, D. Carbone<sup>1</sup>, M. Cavallaro<sup>1</sup>, L.E. Charon Garcia<sup>13</sup>, E.R. Chávez Lomelí<sup>13</sup>, R. Chen<sup>30</sup>, I. Ciraldo<sup>1,2</sup>, M. Colonna<sup>1</sup>, G. D'Agostino<sup>1,2</sup>, F. Delaunay<sup>4,6,22</sup>, N. Deshmukh<sup>23</sup>, H. Djapo<sup>16</sup>, G. De Geronimo<sup>21</sup>, K. De Los Rios<sup>13</sup>, C. Ferraresi<sup>4,8</sup>, J.L. Ferreira<sup>10</sup>, J. Ferretti<sup>32</sup>, P. Finocchiaro<sup>1</sup>, S. Firat<sup>16</sup>, M. Fisichella<sup>4</sup>, A. Foti<sup>3</sup>, G. Gallo<sup>1,2</sup>, H. Garcia-Tecocoatzi<sup>5,24</sup>, A. Hacisalihoglu<sup>25</sup>, A. Huerta-Hernandez<sup>13</sup>, Z.J. Kotila<sup>19</sup>, Y. Kucuk<sup>16</sup>, F. Iazzi<sup>4,6</sup>, G. Lanzalone<sup>1,7</sup>, J.A. Lay<sup>20</sup>, L. La Fauci<sup>1,2</sup>, F. La Via<sup>14</sup>, H. Lenske<sup>15</sup>, R. Linares<sup>10</sup>, D. Lo Presti<sup>2,3</sup>, J. Lubian<sup>10</sup>, J. Ma<sup>30</sup>, D. Marín-Lámbarri<sup>13</sup>, J. Mas Ruiz<sup>13</sup>, N.H. Medina<sup>9</sup>, D. R. Mendes<sup>10</sup>, P. Mereu<sup>4</sup>, M. Moralles<sup>26</sup>, L. Neri<sup>1</sup>, J.R.B. Oliveira<sup>9</sup>, A. Pakou<sup>11</sup>, L. Pandola<sup>1</sup>, H. Petrascu<sup>18</sup>, N. Pietralla<sup>29</sup>, F. Pinna<sup>4,6</sup>, S. Reito<sup>3</sup>, P. Ries<sup>29</sup>, M.R.D. Rodrigues<sup>9</sup>, A. D. Russo<sup>1</sup>, G. Russo<sup>2,3</sup>, E. Santopinto<sup>5</sup>, R.B.B. Santos<sup>33</sup>, L. Serbina<sup>18</sup>, O. Sgouros<sup>1</sup>, M.A.G. da Silveira<sup>33</sup>, S.O. Solakci<sup>16</sup>, G. Souliotis<sup>12</sup>, V. Soukeras<sup>1</sup>, A. Spatafora<sup>1,2</sup>, D. Torresi<sup>1</sup>, S. Tudisco<sup>1</sup>, H. Vargas Hernandez<sup>13</sup>, R.I.M. Vsevolodovna<sup>5,24</sup>, J.S. Wang<sup>30</sup>, V. Werner<sup>29</sup>, Y.Y. Yang<sup>30</sup>, A. Yildirin<sup>16</sup>, V.A.B. Zagatto<sup>10</sup>

<sup>1</sup>Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud, Catania, Italy

<sup>2</sup>Dipartimento di Fisica e Astronomia “Ettore Majorana”, Università di Catania, Catania, Italy

<sup>3</sup>Istituto Nazionale di Fisica Nucleare, Sezione di Catania, Catania, Italy

<sup>4</sup>Istituto Nazionale di Fisica Nucleare, Sezione di Torino, Torino, Italy

<sup>5</sup>Istituto Nazionale di Fisica Nucleare, Sezione di Genova, Genova, Italy

<sup>6</sup>DISAT, Politecnico di Torino, Torino, Italy

<sup>7</sup>Università degli Studi di Enna "Kore", Enna, Italy

<sup>8</sup>DIMEAS, Politecnico di Torino, Torino, Italy

<sup>9</sup>Instituto de Fisica, Universidade de Sao Paulo, Sao Paulo, Brazil

<sup>10</sup>Instituto de Fisica, Universidade Federal Fluminense, Niterói, Brazil

<sup>11</sup>Department of Physics and HINP, The University of Ioannina, Ioannina, Greece

<sup>12</sup>Department of Chemistry, National and Kapodistrian University of Athens, Athens, Greece

<sup>13</sup>Instituto de Física, Universidad Nacional Autónoma de México, México

<sup>14</sup>CNR-IMM, Sezione di Catania, Catania, Italy

<sup>15</sup>Department of Physics, University of Giessen, Giessen, Germany

<sup>16</sup>Department of Physics, Akdeniz University, Antalya, Turkey

<sup>17</sup>School of Physics and Astronomy Tel Aviv University, Israel

<sup>18</sup>IFIN-HH, Romania

<sup>19</sup>University of Jyväskylä, Jyväskylä, Finland

<figure><img src="image_5.png" /></figure>

Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
Recent results on heavy-ion induced reactions of interest for
neutrinoless double beta decay at INFN-LNS

F. Cappuzzello<sup>1,2, (a)</sup>, C. Agodi<sup>1</sup>, L. Acosta<sup>13</sup>, C. Altana<sup>1</sup>, P. Amador-Valenzuela<sup>27</sup>, N. Auerbach<sup>17</sup>, J. Barea<sup>31</sup>, J. Bellone<sup>1,2</sup>, R. Bijker<sup>28</sup>, D. Bonanno<sup>3</sup>, T. Borello-Lewin<sup>9</sup>, I. Boztosun<sup>16</sup>, V. Branchina<sup>3</sup>, S. Brasolin<sup>4</sup>, G. Brischetto<sup>1,2,34</sup>, O. Brunasso<sup>4</sup>, S. Burrello<sup>1,20</sup>, S. Calabrese<sup>1,2</sup>, L. Calabretta<sup>1</sup>, D. Calvo<sup>4</sup>, V. Capirossi<sup>4,6</sup>, D. Carbone<sup>1</sup>, M. Cavallaro<sup>1</sup>, L.E. Charon Garcia<sup>13</sup>, E.R. Chávez Lomelí<sup>13</sup>, R. Chen<sup>30</sup>, I. Ciraldo<sup>1,2</sup>, M. Colonna<sup>1</sup>, G. D'Agostino<sup>1,2</sup>, F. Delaunay<sup>4,6,22</sup>, N. Deshmukh<sup>23</sup>, H. Djapo<sup>16</sup>, G. De Geronimo<sup>21</sup>, K. De Los Rios<sup>13</sup>, C. Ferraresi<sup>4,8</sup>, J.L. Ferreira<sup>10</sup>, J. Ferretti<sup>32</sup>, P. Finocchiaro<sup>1</sup>, S. Firat<sup>16</sup>, M. Fisichella<sup>4</sup>, A. Foti<sup>3</sup>, G. Gallo<sup>1,2</sup>, H. Garcia-Tecocoatzi<sup>5,24</sup>, A. Hacisalihoglu<sup>25</sup>, A. Huerta-Hernandez<sup>13</sup>, Z.J. Kotila<sup>19</sup>, Y. Kucuk<sup>16</sup>, F. Iazzi<sup>4,6</sup>, G. Lanzalone<sup>1,7</sup>, J.A. Lay<sup>20</sup>, L. La Fauci<sup>1,2</sup>, F. La Via<sup>14</sup>, H. Lenske<sup>15</sup>, R. Linares<sup>10</sup>, D. Lo Presti<sup>2,3</sup>, J. Lubian<sup>10</sup>, J. Ma<sup>30</sup>, D. Marín-Lámbarri<sup>13</sup>, J. Mas Ruiz<sup>13</sup>, N.H. Medina<sup>9</sup>, D. R. Mendes<sup>10</sup>, P. Mereu<sup>4</sup>, M. Moralles<sup>26</sup>, L. Neri<sup>1</sup>, J.R.B. Oliveira<sup>9</sup>, A. Pakou<sup>11</sup>, L. Pandola<sup>1</sup>, H. Petrascu<sup>18</sup>, N. Pietralla<sup>29</sup>, F. Pinna<sup>4,6</sup>, S. Reito<sup>3</sup>, P. Ries<sup>29</sup>, M.R.D. Rodrigues<sup>9</sup>, A. D. Russo<sup>1</sup>, G. Russo<sup>2,3</sup>, E. Santopinto<sup>5</sup>, R.B.B. Santos<sup>33</sup>, L. Serbina<sup>18</sup>, O. Sgouros<sup>1</sup>, M.A.G. da Silveira<sup>33</sup>, S.O. Solakci<sup>16</sup>, G. Souliotis<sup>12</sup>, V. Soukeras<sup>1</sup>, A. Spatafora<sup>1,2</sup>, D. Torresi<sup>1</sup>, S. Tudisco<sup>1</sup>, H. Vargas Hernandez<sup>13</sup>, R.I.M. Vsevolodovna<sup>5,24</sup>, J.S. Wang<sup>30</sup>, V. Werner<sup>29</sup>, Y.Y. Yang<sup>30</sup>, A. Yildirin<sup>16</sup>, V.A.B. Zagatto<sup>10</sup>

<sup>1</sup>Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud, Catania, Italy

<sup>2</sup>Dipartimento di Fisica e Astronomia “Ettore Majorana”, Università di Catania,
Catania, Italy

<sup>3</sup>Istituto Nazionale di Fisica Nucleare, Sezione di Catania, Catania, Italy

<sup>4</sup>Istituto Nazionale di Fisica Nucleare, Sezione di Torino, Torino, Italy

<sup>5</sup>Istituto Nazionale di Fisica Nucleare, Sezione di Genova, Genova, Italy

<sup>6</sup>DISAT, Politecnico di Torino, Torino, Italy

<sup>7</sup>Università degli Studi di Enna "Kore", Enna, Italy

<sup>8</sup>DIMEAS, Politecnico di Torino, Torino, Italy

<sup>9</sup>Instituto de Fisica, Universidade de Sao Paulo, Sao Paulo, Brazil

<sup>10</sup>Instituto de Fisica, Universidade Federal Fluminense, Niterói, Brazil

<sup>11</sup>Department of Physics and HINP, The University of Ioannina, Ioannina, Greece

<sup>12</sup>Department of Chemistry, National and Kapodistrian University of Athens, Athens, Greece

<sup>13</sup>Instituto de Física, Universidad Nacional Autónoma de México, México

<sup>14</sup>CNR-IMM, Sezione di Catania, Catania, Italy

<sup>15</sup>Department of Physics, University of Giessen, Giessen, Germany

<sup>16</sup>Department of Physics, Akdeniz University, Antalya, Turkey

<sup>17</sup>School of Physics and Astronomy Tel Aviv University, Israel

<sup>18</sup>IFIN-HH, Romania

<sup>19</sup>University of Jyväskylä, Jyväskylä, Finland

<figure><img src="image_5.png" /></figure>

Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution
of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
<sup>20</sup>Departamento de FAMN, Universidad de Sevilla, Sevilla, Spain

<sup>21</sup>Stony Brook University, USA

<sup>22</sup>LPC Caen, Normandie Université, ENSICAEN, UNICAEN, CNRS/IN2P3, Caen, France

<sup>23</sup>Nuclear Physics Division, Saha Institute of Nuclear Physics, India

<sup>24</sup>Dipartimento di Fisica, Università di Genova, Italy

<sup>25</sup>Institute of Natural Sciences, Karadeniz Teknik University, Turkey

<sup>26</sup>Instituto de Pesquisas Energeticas e Nucleares IPEN/CNEN, Brazil

<sup>27</sup>Instituto Nacional de Investigaciones Nucleares, Mexico

<sup>28</sup>Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, México

<sup>29</sup>Institut fur Kernphysik, Technische Universitat Darmstadt, Germany

<sup>30</sup>Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, China

<sup>31</sup>Universidad de Conception, Chile

<sup>32</sup>Department of Physics, Yale University, USA

<sup>33</sup>Centro Universitario FEI Sao Bernardo do Campo, Brazil

<sup>34</sup>Centro Siciliano di Fisica Nucleare e Struttura della Materia, Italy
the author addresses here

a) Corresponding author: cappuzzello@lns.infn.it

**Abstract:** The NUMEN project aims at accessing experimentally driven information on Nuclear Matrix Elements (NME) involved in the half-life of the neutrinoless double beta decay (0vββ). In this view measurements of Heavy Ion (HI) induced Double Charge Exchange (DCE) reaction cross sections are performed with high-accuracy. In particular, the (¹⁸O,¹⁸Ne) and (²⁰Ne,²⁰O) reactions are used as tools for β⁺β⁺ and β⁻β⁻ decays, respectively. In the experiments, performed at INFN - Laboratory Nazionali del Sud (LNS) in Catania, the beams are accelerated by the Superconducting Cyclotron (CS) and the reaction ejectiles are detected the MAGNEX magnetic spectrometer. The measured cross sections are challenging low (a few nb), being the total reaction cross section much larger (a few b), thus a high sensitivity and a large rejection capability are demanded to the experimental set-up. This limits the present exploration to few selected isotopes of interest in the context of typically low-yield experimental runs. A major upgrade of the LNS facility is under way in order to increase the experimental dataset of more than two orders of magnitude, still preserving the high sensitivity of the present set-up. When accomplished this effort will make the INFN-LNS as the state-of-the-art research infrastructure for the systematic study of all the cases of interest for 0vββ. In this view, frontiers technologies are going to be adopted for the accelerator and the detection systems. In parallel, advanced theoretical models are being developed in order to extract the nuclear structure information from the measured cross sections

# 1. Introduction

The neutrinoless double beta decay (0vββ) is nowadays the most promising resource to establish the Majorana nature of neutrinos and potentially to shed light on the absolute neutrino mass and hierarchy. A critical aspect is that the associated Nuclear Matrix Elements (NME) must be known with good accuracy, despite the intrinsic many-body nature of the involved states of the parent and daughter nuclei makes this task particularly demanding. An updated comparison of the results of NME calculations, obtained within various nuclear structure frameworks [1-4], indicates that significant differences are indeed found, which makes the present situation not satisfactory. In addition, some assumption common to different competing calculations, like the unavoidable truncation of the nuclear many body wave- function, could cause overall systematic uncertainties.
<sup>20</sup>Departamento de FAMN, Universidad de Sevilla, Sevilla, Spain

<sup>21</sup>Stony Brook University, USA

<sup>22</sup>LPC Caen, Normandie Université, ENSICAEN, UNICAEN, CNRS/IN2P3, Caen, France

<sup>23</sup>Nuclear Physics Division, Saha Institute of Nuclear Physics, India

<sup>24</sup>Dipartimento di Fisica, Università di Genova, Italy

<sup>25</sup>Institute of Natural Sciences, Karadeniz Teknik University, Turkey

<sup>26</sup>Instituto de Pesquisas Energeticas e Nucleares IPEN/CNEN, Brazil

<sup>27</sup>Instituto Nacional de Investigaciones Nucleares, Mexico

<sup>28</sup>Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, México

<sup>29</sup>Institut fur Kernphysik, Technische Universitat Darmstadt, Germany

<sup>30</sup>Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, China

<sup>31</sup>Universidad de Conception, Chile

<sup>32</sup>Department of Physics, Yale University, USA

<sup>33</sup>Centro Universitario FEI Sao Bernardo do Campo, Brazil

<sup>34</sup>Centro Siciliano di Fisica Nucleare e Struttura della Materia, Italy
the author addresses here

a) Corresponding author: cappuzzello@lns.infn.it

**Abstract:** The NUMEN project aims at accessing experimentally driven information on Nuclear Matrix Elements (NME) involved in the half-life of the neutrinoless double beta decay (0vββ). In this view measurements of Heavy Ion (HI) induced Double Charge Exchange (DCE) reaction cross sections are performed with high-accuracy. In particular, the (¹⁸O,¹⁸Ne) and (²⁰Ne,²⁰O) reactions are used as tools for β⁺β⁺ and β⁻β⁻ decays, respectively. In the experiments, performed at INFN - Laboratory Nazionali del Sud (LNS) in Catania, the beams are accelerated by the Superconducting Cyclotron (CS) and the reaction ejectiles are detected the MAGNEX magnetic spectrometer. The measured cross sections are challenging low (a few nb), being the total reaction cross section much larger (a few b), thus a high sensitivity and a large rejection capability are demanded to the experimental set-up. This limits the present exploration to few selected isotopes of interest in the context of typically low-yield experimental runs. A major upgrade of the LNS facility is under way in order to increase the experimental dataset of more than two orders of magnitude, still preserving the high sensitivity of the present set-up. When accomplished this effort will make the INFN-LNS as the state-of-the-art research infrastructure for the systematic study of all the cases of interest for 0vββ. In this view, frontiers technologies are going to be adopted for the accelerator and the detection systems. In parallel, advanced theoretical models are being developed in order to extract the nuclear structure information from the measured cross sections

# 1. Introduction

The neutrinoless double beta decay (0vββ) is nowadays the most promising resource to establish the Majorana nature of neutrinos and potentially to shed light on the absolute neutrino mass and hierarchy. A critical aspect is that the associated Nuclear Matrix Elements (NME) must be known with good accuracy, despite the intrinsic many-body nature of the involved states of the parent and daughter nuclei makes this task particularly demanding. An updated comparison of the results of NME calculations, obtained within various nuclear structure frameworks [1-4], indicates that significant differences are indeed found, which makes the present situation not satisfactory. In addition, some assumption common to different competing calculations, like the unavoidable truncation of the nuclear many body wave- function, could cause overall systematic uncertainties.
NUMEN [5-7] proposes to use HI-DCE reactions as tools to access quantitative information, relevant for $0\nu\beta\beta$ decay NME. These reactions are characterized by the transfer of two charge units, leaving the mass number unchanged, and can proceed by a sequential nucleon-transfer mechanism or by exchange of two isovector mesons, in an uncorrelated or correlated fashion. Despite $0\nu\beta\beta$ decays and HI-DCE reactions are mediated by different interactions, they present a number of similarities. Among those, the key aspects are that initial and final nuclear states are the same and the transition operators in both cases present a superposition of short-range isospin, spin-isospin and rank-two tensor components with a relevant available momentum (100 MeV/c or so).

In addition, NUMEN aims at the exploration of all the relevant reaction channels promoted by the projectile/target interaction. They include elastic and inelastic scattering, single and double nucleon transfer reactions and single charge exchange reactions.

## 2. Status of the NUMEN project

NUMEN is conceived in a long-range time perspective, in the view of a comprehensive study of many candidate systems for $0\nu\beta\beta$ decay. Moreover, the project promotes and is strictly connected with a renewal of the INFN-LNS research infrastructure and with a specific R&D activity on detectors, materials and instrumentation.

In the last years the project has been developing (NUMEN Phase2) following a threefold scheme: measuring DCE cross sections for a few cases of interest; making a deep R&D investigation for the new detection technologies to be used for the future high luminosity beams; developing a fully microscopic and quantum theory for DCE reactions, specifically conceived to extract nuclear structure information from measured cross sections. Below some of the main achievements of this activity is outlined.

## 3. The experiments

The experimental campaigns have been conducted so far at INFN-LNS, using the K800 Superconducting Cyclotron to accelerate beams and the MAGNEX large acceptance magnetic spectrometer for the detection of the ejectiles.

MAGNEX is a large acceptance magnetic device made up of a large aperture vertically focusing quadrupole and a horizontally bending dipole magnet. It allows the identification of heavy ions with quite high mass (ΔA/A~1/160), angle (Δθ~0.2°) and energy resolutions (ΔE/E~1/1000), within a large solid angle (Ω~50 msr) and momentum range (-14% < Δp/p < +10%). High-resolution measurements for quasi-elastic processes, characterized by differential cross-sections falling down to tens of nb/sr, were already performed by this setup [8-14]. A crucial feature is the implementation of a technique of trajectory reconstruction, based on differential algebraic techniques, which allows solving the equation of motion of each detected particle to 10th order [15].

The experimental activity proposed and presently in progress consists of two main classes of experiments, corresponding to the exploration of the two directions of isospin lowering $\tau^-$-$\tau^+$ and rising $\tau^+\tau^+$, characteristic of $\beta^+\beta^-$ and $\beta^+\beta^+$ decays respectively [16-18].

### 3.1. *Experiments with <sup>18</sup>O Beam (β<sup>+</sup>β<sup>+</sup> Direction)*

For the experiments of this class, the reaction channels of our interest are: elastic and inelastic scattering ($^{18}$O,$^{18}$O); DCE reaction ($^{18}$O,$^{18}$Ne); charge-exchange reaction ($^{18}$O,$^{19}$F); two-proton pickup reaction ($^{18}$O,$^{20}$Ne); one-proton pickup reaction ($^{18}$O,$^{19}$F); two-neutron stripping reaction ($^{18}$O,$^{16}$O); one-neutron stripping reaction ($^{18}$O,$^{17}$O).

One of the main challenges of such experiments is the measurement at very forward angles, including zero-degree. This is performed by placing the spectrometer with its optical axis at +3° with respect to the beam axis. Thanks to its large angular acceptance, a range $-2° < \theta_{\text{lab}} < 9°$ is thus covered.

$^{116}$Sn, $^{76}$Se and $^{48}$Ti are the targets already explored via ($^{18}$O,$^{18}$Ne) reaction at 15 and 22 AMeV in order to study the $^{116}$Sn → $^{116}$Cd, $^{76}$Se → $^{76}$Ge and $^{48}$Ti → $^{48}$Ca transitions, respectively, and the competing channels as mentioned above. The reduction and analysis of the collected data is presently in progress.
NUMEN [5-7] proposes to use HI-DCE reactions as tools to access quantitative information, relevant for $0\nu\beta\beta$ decay NME. These reactions are characterized by the transfer of two charge units, leaving the mass number unchanged, and can proceed by a sequential nucleon-transfer mechanism or by exchange of two isovector mesons, in an uncorrelated or correlated fashion. Despite $0\nu\beta\beta$ decays and HI-DCE reactions are mediated by different interactions, they present a number of similarities. Among those, the key aspects are that initial and final nuclear states are the same and the transition operators in both cases present a superposition of short-range isospin, spin-isospin and rank-two tensor components with a relevant available momentum (100 MeV/c or so).

In addition, NUMEN aims at the exploration of all the relevant reaction channels promoted by the projectile/target interaction. They include elastic and inelastic scattering, single and double nucleon transfer reactions and single charge exchange reactions.

## 2. Status of the NUMEN project

NUMEN is conceived in a long-range time perspective, in the view of a comprehensive study of many candidate systems for $0\nu\beta\beta$ decay. Moreover, the project promotes and is strictly connected with a renewal of the INFN-LNS research infrastructure and with a specific R&D activity on detectors, materials and instrumentation.

In the last years the project has been developing (NUMEN Phase2) following a threefold scheme: measuring DCE cross sections for a few cases of interest; making a deep R&D investigation for the new detection technologies to be used for the future high luminosity beams; developing a fully microscopic and quantum theory for DCE reactions, specifically conceived to extract nuclear structure information from measured cross sections. Below some of the main achievements of this activity is outlined.

## 3. The experiments

The experimental campaigns have been conducted so far at INFN-LNS, using the K800 Superconducting Cyclotron to accelerate beams and the MAGNEX large acceptance magnetic spectrometer for the detection of the ejectiles.

MAGNEX is a large acceptance magnetic device made up of a large aperture vertically focusing quadrupole and a horizontally bending dipole magnet. It allows the identification of heavy ions with quite high mass (ΔA/A~1/160), angle (Δθ~0.2°) and energy resolutions (ΔE/E~1/1000), within a large solid angle (Ω~50 msr) and momentum range (-14% < Δp/p < +10%). High-resolution measurements for quasi-elastic processes, characterized by differential cross-sections falling down to tens of nb/sr, were already performed by this setup [8-14]. A crucial feature is the implementation of a technique of trajectory reconstruction, based on differential algebraic techniques, which allows solving the equation of motion of each detected particle to 10th order [15].

The experimental activity proposed and presently in progress consists of two main classes of experiments, corresponding to the exploration of the two directions of isospin lowering $\tau^-$-$\tau^+$ and rising $\tau^+\tau^+$, characteristic of $\beta^+\beta^-$ and $\beta^+\beta^+$ decays respectively [16-18].

### 3.1. *Experiments with <sup>18</sup>O Beam (β<sup>+</sup>β<sup>+</sup> Direction)*

For the experiments of this class, the reaction channels of our interest are: elastic and inelastic scattering ($^{18}$O,$^{18}$O); DCE reaction ($^{18}$O,$^{18}$Ne); charge-exchange reaction ($^{18}$O,$^{19}$F); two-proton pickup reaction ($^{18}$O,$^{20}$Ne); one-proton pickup reaction ($^{18}$O,$^{19}$F); two-neutron stripping reaction ($^{18}$O,$^{16}$O); one-neutron stripping reaction ($^{18}$O,$^{17}$O).

One of the main challenges of such experiments is the measurement at very forward angles, including zero-degree. This is performed by placing the spectrometer with its optical axis at +3° with respect to the beam axis. Thanks to its large angular acceptance, a range $-2° < \theta_{\text{lab}} < 9°$ is thus covered.

$^{116}$Sn, $^{76}$Se and $^{48}$Ti are the targets already explored via ($^{18}$O,$^{18}$Ne) reaction at 15 and 22 AMeV in order to study the $^{116}$Sn → $^{116}$Cd, $^{76}$Se → $^{76}$Ge and $^{48}$Ti → $^{48}$Ca transitions, respectively, and the competing channels as mentioned above. The reduction and analysis of the collected data is presently in progress.
## 3.2. Experiments with $^{20}$Ne Beam ($\beta^-$ $\beta^-$ Direction)

In the class of experiments with $^{20}$Ne$^{10+}$ beams, the reaction channels we are interested in are the following: Elastic and inelastic scattering ($^{20}$Ne,$^{20}$Ne); DCE reaction ($^{20}$Ne,$^{20}$O); Charge Exchange reaction ($^{20}$Ne,$^{20}$F); Two-proton stripping reaction ($^{20}$Ne,$^{18}$O); One-proton stripping reaction ($^{20}$Ne,$^{19}$F); Two-neutron pickup reaction ($^{20}$Ne,$^{22}$Ne); One-neutron pickup reaction ($^{20}$Ne,$^{21}$Ne).

The spectrometer optical axis is typically placed at -3°, thus the covered angular range is $-8° < \theta_{\text{lab}} < +3°$.

A peculiarity of these experiments is that the beam components $^{20}$Ne$^{9+}$ and 20Ne$^{8+}$, produced by the interaction of the beam with the electrons of the target material, have a magnetic rigidity similar to the ions of interest. Therefore, they enter in the FPD acceptance, causing a limitation in the rate tolerable by the detector. In order to mitigate this problem two aluminium shields are mounted upstream the sensitive region of the focal plane detector. In addition, an appropriate second foil (post-stripper) is mounted downstream of the isotopic target. Recently a specific study of different materials to be used as post-stripper has been performed [19].

The systems already experimentally explored using the ($^{20}$Ne,$^{20}$O) reaction at 15 AMeV are the $^{116}$Cd target (to study the $^{116}$Cd → $^{116}$Sn transition), the $^{130}$Te (for the $^{130}$Te → $^{130}$Xe) and the $^{76}$Ge (for the $^{76}$Ge → $^{76}$Se). The data reduction and analysis is in progress.

## 4. FEATURES OF R&D

The results of NUMEN Phase 1 indicate that suitable information from DCE reactions can be extracted [8]. However, for a systematic exploration of all the cases of interest for 0vbb a much larger dataset of DCE data is necessary, including statistically significant data at different bombarding energies and with several isotopic targets. These considerations suggest that the DCE experiments should be performed with much higher beam current. In particular, for a systematic study of the many “hot” cases of $\beta\beta$ decays, an upgraded set-up, able to work with a two or three orders of magnitude higher current than the present, is necessary. As a consequence, the present limits of beam power (~100 W) for the CS accelerator and acceptable rate for the MAGNEX focal plane detector (few kHz) must be sensibly revised. This goal can be achieved by a substantial change in the technologies implemented in the beam extraction, in the detection of the ejectiles and in the target cooling. For the accelerator the change of the beam extraction technology from electrostatic deflector to a stripper foil is an adequate choice [20]. For the spectrometer the main foreseen upgrades are:

1. The construction of a FPD tracker based on micro patterned gas detector [21];

2. The construction of a wall of telescopes of SiC-CsI detectors for ion identification [22-23];

3. The introduction of an array of scintillators for measuring the coincident $\gamma$-rays;

4. The development of suitable front-end and read-out electronics, for a fast read-out of the detector signals, a high signal to noise ratio and adequate hardness to radiation [24];

5. The implementation of a suitable architecture for data acquisition, storage and data handling, including accurate detector response simulations;

6. The enhancement of the maximum accepted magnetic rigidity, with minimal distortion of the measured magnetic field for the optical elements [25-26];

7. The installation of a beam dump to stop the high power beams.

In addition, we are developing the technology for suitable nuclear targets to be used in the experiments. Here the challenge is to produce and cool isotopically enriched thin films able to resist to the high power dissipated by the interaction of the intense beams with the target [27].

## 5. Development of DCE theory

NUMEN is fostering the development of a specific theory program to allow an accurate extraction of nuclear structure information from the measured cross sections.
## 3.2. Experiments with $^{20}$Ne Beam ($\beta^-$ $\beta^-$ Direction)

In the class of experiments with $^{20}$Ne$^{10+}$ beams, the reaction channels we are interested in are the following: Elastic and inelastic scattering ($^{20}$Ne,$^{20}$Ne); DCE reaction ($^{20}$Ne,$^{20}$O); Charge Exchange reaction ($^{20}$Ne,$^{20}$F); Two-proton stripping reaction ($^{20}$Ne,$^{18}$O); One-proton stripping reaction ($^{20}$Ne,$^{19}$F); Two-neutron pickup reaction ($^{20}$Ne,$^{22}$Ne); One-neutron pickup reaction ($^{20}$Ne,$^{21}$Ne).

The spectrometer optical axis is typically placed at -3°, thus the covered angular range is $-8° < \theta_{\text{lab}} < +3°$.

A peculiarity of these experiments is that the beam components $^{20}$Ne$^{9+}$ and 20Ne$^{8+}$, produced by the interaction of the beam with the electrons of the target material, have a magnetic rigidity similar to the ions of interest. Therefore, they enter in the FPD acceptance, causing a limitation in the rate tolerable by the detector. In order to mitigate this problem two aluminium shields are mounted upstream the sensitive region of the focal plane detector. In addition, an appropriate second foil (post-stripper) is mounted downstream of the isotopic target. Recently a specific study of different materials to be used as post-stripper has been performed [19].

The systems already experimentally explored using the ($^{20}$Ne,$^{20}$O) reaction at 15 AMeV are the $^{116}$Cd target (to study the $^{116}$Cd → $^{116}$Sn transition), the $^{130}$Te (for the $^{130}$Te → $^{130}$Xe) and the $^{76}$Ge (for the $^{76}$Ge → $^{76}$Se). The data reduction and analysis is in progress.

## 4. FEATURES OF R&D

The results of NUMEN Phase 1 indicate that suitable information from DCE reactions can be extracted [8]. However, for a systematic exploration of all the cases of interest for 0vbb a much larger dataset of DCE data is necessary, including statistically significant data at different bombarding energies and with several isotopic targets. These considerations suggest that the DCE experiments should be performed with much higher beam current. In particular, for a systematic study of the many “hot” cases of $\beta\beta$ decays, an upgraded set-up, able to work with a two or three orders of magnitude higher current than the present, is necessary. As a consequence, the present limits of beam power (~100 W) for the CS accelerator and acceptable rate for the MAGNEX focal plane detector (few kHz) must be sensibly revised. This goal can be achieved by a substantial change in the technologies implemented in the beam extraction, in the detection of the ejectiles and in the target cooling. For the accelerator the change of the beam extraction technology from electrostatic deflector to a stripper foil is an adequate choice [20]. For the spectrometer the main foreseen upgrades are:

1. The construction of a FPD tracker based on micro patterned gas detector [21];

2. The construction of a wall of telescopes of SiC-CsI detectors for ion identification [22-23];

3. The introduction of an array of scintillators for measuring the coincident $\gamma$-rays;

4. The development of suitable front-end and read-out electronics, for a fast read-out of the detector signals, a high signal to noise ratio and adequate hardness to radiation [24];

5. The implementation of a suitable architecture for data acquisition, storage and data handling, including accurate detector response simulations;

6. The enhancement of the maximum accepted magnetic rigidity, with minimal distortion of the measured magnetic field for the optical elements [25-26];

7. The installation of a beam dump to stop the high power beams.

In addition, we are developing the technology for suitable nuclear targets to be used in the experiments. Here the challenge is to produce and cool isotopically enriched thin films able to resist to the high power dissipated by the interaction of the intense beams with the target [27].

## 5. Development of DCE theory

NUMEN is fostering the development of a specific theory program to allow an accurate extraction of nuclear structure information from the measured cross sections.
In ref. [28-30] the heavy ion induced Single Charge Exchange (SCE) have been analysed in detail in the view of the connection to single beta decay NME. It was shown that the surface localization of the SCE, due the strong absorption of the target-projectile nucleus-nucleus potential, allows for a strong simplification of the reaction description, making the isovector meson exchange mechanism relevant at forward detection angles.

The development of a second order perturbation theory for DCE is being accomplished relying on the use of the DWBA approximation for the cross section. The theory is focused on the development of microscopic models for DCE reactions, employing several approaches (QRPA, shell model, IBM) for inputs connected to nuclear structure quantities. We are also investigating the possible link between the theoretical description of the 0vββ decay and DCE reactions [30-32].

## References

[1] A J.D. Vergados, H. Ejiri, and F. Simkovic, Reports on Progress in Physics **75**, 106301 (2012).

[2] H. Ejiri, J. Suhonen, K. Zuber, Phys. Rep. **797**, 1 (2019).

[3] J. Barea, J. Kotila, F. Iachello, Phys. Rev. Lett. **109**, 042501 (2012).

[4] S. Dell'Oro, S. Marcocci, M. Viel and F. Vissani, Advances in High Energy Physics **2016**, 2162659 (2016).

[5] F. Cappuzzello et al. Eur. Phys. Jour. A **54**, 72 (2018).

[6] F. Cappuzzello et al. Journal of Physics Conference Series **630**, 012018 (2015).

[7] C. Agodi, F. Cappuzzello et al. Nuclear and Particle Physics Proceedings **265**, 28-30 (2015).

[8] F. Cappuzzello, M. Cavallaro et al. Eur. Phys. J. A **51**, 145 (2015).

[9] F. Cappuzzello et al., Eur. Phys. J. A **52**, 169 (2016).

[10] D. Carbone et al., Phys. Rev. C **95**, 034603 (2017).

[11] M. Cavallaro et al., Phys. Rev. C **93**, 064323 (2016).

[12] M. J. Ermamatov et al., Phys. Rev. C **94**, 024610 (2016).

[13] D. Carbone et al., Journal of Physics: Conference Series 312, 082016 (2011).

[14] F. Cappuzzello et al., Nucl. Instr. and Meth. A **763**, 314 (2014).

[15] F. Cappuzzello, et al., Nucl. Instr. and Meth. A **638**, 74 (2011).

[16] F. Cappuzzello et al., Eur. Phys. J. A **51**, 145 (2015).

[17] S. Calabrese et al., Acta Phys. Pol. B **49**, 275 (2018).

[18] M. Cavallaro et al., Nucl. Instr. and Meth. B (in press) https://doi.org/10.1016/j.nimb.2019.04.069.

[19] M. Cavallaro et al., Results in Phys. **13**, 102191 (2019).

[20] L. Calabretta et al. Modern Physics Letters A **32**, 17 (2017).

[21] M. Cortesi, S. Rost, W. Mittig, et al. Review of Scientific Instruments **88**, 013303 (2017).

[22] S. Tudisco, F. La Via, C. Agodi, et al. Sensors **18**, 2289 (7).

[23] D. Carbone, M. Cavallaro et al., Results in Physics **6**, 863 (2016).

[24] G. De Geronimo et al. IEEE Transactions on Nuclear Science **60**, 2314-2321 (2013).

[25] A. Lazzaro, F. Cappuzzello, A. Cunsolo et al., Nucl. Instr. and Methods A **585**, 136 (2008).

[26] A. Lazzaro, F. Cappuzzello, A. Cunsolo et al., Nucl. Instr. and Methods A **602**, 494 (2009).

[27] F. Iazzi, S. Ferrero, R. Introzzi et al., WIT Transactions on Engineering Sciences **116**, 61 (2017).

[28] F. Cappuzzello et al., Nuclear Physics A **739**, 30, (2004).

[29] H. Lenske et al., Phys. Rev. C **98**, 044620 (2018).

[30] H. Lenske et al. Prog. Part. And Nucl. Phys., **109**, 103716 (2019).

[31] E. Santopinto et al., Phys. Rev. C **98**, 061601(R) (2018).

[32] J.I. Bellone et al., J. Phys. Conf. Ser. **1056**, 012004 (2018).
In ref. [28-30] the heavy ion induced Single Charge Exchange (SCE) have been analysed in detail in the view of the connection to single beta decay NME. It was shown that the surface localization of the SCE, due the strong absorption of the target-projectile nucleus-nucleus potential, allows for a strong simplification of the reaction description, making the isovector meson exchange mechanism relevant at forward detection angles.

The development of a second order perturbation theory for DCE is being accomplished relying on the use of the DWBA approximation for the cross section. The theory is focused on the development of microscopic models for DCE reactions, employing several approaches (QRPA, shell model, IBM) for inputs connected to nuclear structure quantities. We are also investigating the possible link between the theoretical description of the $0v\beta\beta$ decay and DCE reactions [30-32].

## References

[1] A J.D. Vergados, H. Ejiri, and F. Simkovic, Reports on Progress in Physics **75**, 106301 (2012).

[2] H. Ejiri, J. Suhonen, K. Zuber, Phys. Rep. **797**, 1 (2019).

[3] J. Barea, J. Kotila, F. Iachello, Phys. Rev. Lett. **109**, 042501 (2012).

[4] S. Dell'Oro, S. Marcocci, M. Viel and F. Vissani, Advances in High Energy Physics **2016**, 2162659 (2016).

[5] F. Cappuzzello et al. Eur. Phys. Jour. A **54**, 72 (2018).

[6] F. Cappuzzello et al. Journal of Physics Conference Series **630**, 012018 (2015).

[7] C. Agodi, F. Cappuzzello et al. Nuclear and Particle Physics Proceedings **265**, 28-30 (2015).

[8] F. Cappuzzello, M. Cavallaro et al. Eur. Phys. J. A **51**, 145 (2015).

[9] F. Cappuzzello et al., Eur. Phys. J. A **52**, 169 (2016).

[10] D. Carbone et al., Phys. Rev. C **95**, 034603 (2017).

[11] M. Cavallaro et al., Phys. Rev. C **93**, 064323 (2016).

[12] M. J. Ermamatov et al., Phys. Rev. C **94**, 024610 (2016).

[13] D. Carbone et al., Journal of Physics: Conference Series 312, 082016 (2011).

[14] F. Cappuzzello et al., Nucl. Instr. and Meth. A **763**, 314 (2014).

[15] F. Cappuzzello, et al., Nucl. Instr. and Meth. A **638**, 74 (2011).

[16] F. Cappuzzello et al., Eur. Phys. J. A **51**, 145 (2015).

[17] S. Calabrese et al., Acta Phys. Pol. B **49**, 275 (2018).

[18] M. Cavallaro et al., Nucl. Instr. and Meth. B (in press) https://doi.org/10.1016/j.nimb.2019.04.069.

[19] M. Cavallaro et al., Results in Phys. **13**, 102191 (2019).

[20] L. Calabretta et al. Modern Physics Letters A **32**, 17 (2017).

[21] M. Cortesi, S. Rost, W. Mittig, et al. Review of Scientific Instruments **88**, 013303 (2017).

[22] S. Tudisco, F. La Via, C. Agodi, et al. Sensors **18**, 2289 (7).

[23] D. Carbone, M. Cavallaro et al., Results in Physics **6**, 863 (2016).

[24] G. De Geronimo et al. IEEE Transactions on Nuclear Science **60**, 2314-2321 (2013).

[25] A. Lazzaro, F. Cappuzzello, A. Cunsolo et al., Nucl. Instr. and Methods A **585**, 136 (2008).

[26] A. Lazzaro, F. Cappuzzello, A. Cunsolo et al., Nucl. Instr. and Methods A **602**, 494 (2009).

[27] F. Iazzi, S. Ferrero, R. Introzzi et al., WIT Transactions on Engineering Sciences **116**, 61 (2017).

[28] F. Cappuzzello et al., Nuclear Physics A **739**, 30, (2004).

[29] H. Lenske et al., Phys. Rev. C **98**, 044620 (2018).

[30] H. Lenske et al. Prog. Part. And Nucl. Phys., **109**, 103716 (2019).

[31] E. Santopinto et al., Phys. Rev. C **98**, 061601(R) (2018).

[32] J.I. Bellone et al., J. Phys. Conf. Ser. **1056**, 012004 (2018).