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

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 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 270 MeV, give encouraging indication on the capability of the proposed technique to access relevant quantitative information. The two major aspects 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 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.Consejo Europeo de Investigación (ERC)- Horizon 2020 714625 y 65400

Spectroscopy of high-lying resonances in 9 Be by the measurement of ( p , p ), ( p , d ), and ( p , α ) reactions with a radioactive 8 Li beam

We measured the 8 Li ( p , p ) 8 Li , 8 Li ( p , d ) 7 Li , and 8 Li ( p , α ) 5 He reactions at low energies using the thick target inverse kinematics method, with a polyethylene [ CH 2 ] n target and a radioactive 8 Li beam available at the Radioactive Ion Beams in Brazil facility of São Paulo. By measuring simultaneously several reaction channels ( p , p ) , ( p , d ) , and ( p , α ) , the still uncertain high-lying resonances of 9 Be , close to the proton threshold, can be studied and their parameters, such as energy, width, and spin parity can be more reliably determined. The experimental excitation functions of the reactions 8 Li ( p , p ) 8 Li , 8 Li ( p , d ) 7 Li , and 8 Li ( p , α ) 5 He were analyzed using the R -matrix theory, which allows us to infer the properties of the resonances. Multichannel R -matrix analysis provides evidence for a significant clustering in the ( p , d ) channel. The experimental data and the multichannel R -matrix analysis will be presented.Fundação de Amparo à Pesquisa do Estado de São Paulo. Brasil. (FAPESP) 2011/15904-7, 2013/22100-7 y 2016/21434-7VI Plan Propio de Investigación de la Universidad de Sevilla. España. (2017–2018

Understanding the mechanisms of nuclear collisions: A complete study of the B 10 + Sn 120 reaction

Background: Reactions involving exotic and stable weakly bound nuclei have been extensively studied in recent years. Although several models have been successfully used to explain particular reaction outcomes, the answers to many questions remain elusive. In previous works, we presented elastic, inelastic, and transfer angular distributions for the B10+Sn120 system measured at ELab=31.5, 33.0, 35.0, and 37.5 MeV. The data set was analyzed through coupled reaction channels calculations in the context of the double-folding São Paulo potential. Purpose: We investigate nuclear reaction mechanisms for systems involving weakly bound projectiles. Method: Angular distributions for several nuclear reaction processes were measured for the B10+Sn120 system at ELab=39.70 MeV. Results: The new data set involves angular distributions for elastic scattering, projectile and target inelastic excitations, one-neutron pickup transfer, one-proton stripping transfer, deuteron pickup transfer, and He3,4 stripping transfer. We have also observed Be10 nuclei. The effect of the couplings to some nonelastic states on the angular distributions is discussed. Conclusion: The theoretical calculations within the coupled reaction channels formalism provide an overall good agreement with the corresponding inelastic, one-neutron stripping, one-proton pickup, one-deuteron pickup, and He3 stripping transfer data. However, to improve the description of the elastic scattering angular distribution, the inclusion of additional channels in the coupling scheme might be necessary.Fil: Gasques, L. R.. Universidade de Sao Paulo; BrasilFil: Alvarez, M. A. G.. Universidad de Sevilla; EspañaFil: Arazi, Andres. Comisión Nacional de Energía Atómica. Gerencia del Área de Investigación y Aplicaciones No Nucleares. Gerencia Física (Centro Atómico Constituyentes). Proyecto Tandar; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Carlson, B. V.. Instituto Tecnológico de Aeronáutica; BrasilFil: Chamon, L. C.. Universidade de Sao Paulo; BrasilFil: Fernández García, J. P.. Universidad de Sevilla; EspañaFil: Lépine Szily, A.. Universidade de Sao Paulo; BrasilFil: Lubian, J.. Universidade Federal Fluminense; BrasilFil: Rangel, J.. Universidade Federal Fluminense; BrasilFil: Rodríguez Gallardo, M.. Universidad de Sevilla; EspañaFil: Scarduelli, V.. Universidade de Sao Paulo; BrasilFil: Zagatto, V. A. B.. Universidade Federal Fluminense; Brasi

Investigation of the reaction mechanisms for 10 B + 197 Au at near-barrier energies

The 10 B + 197 Au reaction has been investigated through cross-section measurements for different channels, such as quasielastic and elastic scattering, inelastic excitation of low-lying 197 Au states, and one-neutron pickup and one-proton stripping transfer reactions. Experimental angular distributions were obtained for 20 bombardment energies around the Coulomb barrier: 38 ≤ E l a b ≤ 61 MeV . Coupled reaction channels calculations have been performed in the context of the double-folding São Paulo potential, and details of the data analysis are discussed along the paper. In general, the theoretical calculations provide a satisfactory description of the data.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) 2018/09998-8 y 2017/05660-0,Conselho Nacional de Desenvolvimento Científico e Tecnológico de Brasil (CNPq) 407096/2017-5 y 306433/2017-6Instituto Nacional de Ciência e Tecnologia: Física Nuclear de Brasil (INCT-FNA) 464898/2014-5Ministerio de Ciencia, Innovación y Universidades de España. PGC2018-096994-B-C21Ministerio de Economía y Competitividad de España, Fondo de Desarrollo Regional de la Unión Europea (FEDER) FIS2017-88410-PPrograma de investigación e innovación Horizonte 2020 de la Unión Europea.654002Consejo Nacional de Investigaciones Científicas y Técnicas de Argentina (CONICET) PIP00786COFondo para la Investigación Científica y Tecnológica de Argentina (FONCYT) PICT-2017-408

Systematic study of optical potential strengths in reactions on Sn 120 involving strongly bound, weakly bound, and exotic nuclei

We present new experimental angular distributions for the elastic scattering of Li6+Sn120 at three bombarding energies. We include these data in a wide systematic involving the elastic scattering of He4,6,Li7, Be9,B10, and O16,18 projectiles on the same target at energies around the respective Coulomb barriers. Considering this data set, we report on optical model analyses based on the double-folding São Paulo potential. Within this approach, we study the sensitivity of the data fit to different models for the nuclear matter densities and to variations in the optical potential strengths.Fil: Alvarez, M. A. G.. Universidad de Sevilla; EspañaFil: Fernández García, J. P.. Universidad de Sevilla; EspañaFil: León García, J. L.. Universidad de Sevilla; EspañaFil: Rodríguez Gallardo, M.. Universidad de Sevilla; EspañaFil: Gasques, L. R.. Universidade de Sao Paulo; BrasilFil: Chamon, L. C.. Universidade de Sao Paulo; BrasilFil: Zagatto, V. A. B.. Universidade de Sao Paulo; BrasilFil: Lépine Szily, A.. Universidade de Sao Paulo; BrasilFil: Oliveira, J. R. B.. Universidade de Sao Paulo; BrasilFil: Scarduelli, V.. Universidade Federal Fluminense; BrasilFil: Carlson, B. V.. Instituto Tecnologico de Aeronautica.; BrasilFil: Casal, J.. Istituto Nazionale Di Fisica Nucleare.; ItaliaFil: Arazi, Andres. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica; ArgentinaFil: Torres, D. A.. Universidad Nacional de Colombia; ColombiaFil: Ramirez, F.. Universidad Nacional de Colombia; Colombi

Elastic scattering, inelastic excitation, and neutron transfer for Li 7 + Sn 120 at energies around the Coulomb barrier

Experimental angular distributions for the 7 Li + 120 Sn elastic and inelastic (projectile and target excitations) scattering, and for the neutron stripping reaction, have been obtained at E LAB = 20, 22, 24, and 26 MeV, covering an energy range around the Coulomb barrier ( V (LAB) B ≈ 21 . 4 MeV). Coupled channel and coupled reaction channel calculations were performed and both describe satisfactorily the experimental data sets. The 1 2 − state 7 Li inelastic excitation (using a rotational model), as well as the projectile coupling to the continuum ( α plus a tritium particle) play a fundamental role on the proper description of elastic, inelastic, and transfer channels. Couplings to the one-neutron stripping channel do not significantly affect the theoretical elastic scattering angular distributions. The spectroscopic amplitudes of the transfer channel were obtained through a shell model calculation. The theoretical angular distributions for the one-neutron stripping reaction agreed with the experimental data