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

Abstract. The possibility to use a special class of heavy-ion induced direct reactions, such as double charge exchange reactions, is discussed in view of their application to extract information that may be helpful to determinate the nuclear matrix elements entering in the expression of neutrinoless double beta decay halflife. The methodology of the experimental campaign presently running at INFN - Laboratori Nazionali del Sud is reported and the experimental challenges characterizing such activity are describe

New results from the NUMEN project

NUMEN aims at accessing experimentally driven information on Nuclear Matrix Elements (NME) involved in the half-life of the neutrinoless double beta decay (0νββ), by high-accuracy measurements of the cross sections of Heavy Ion (HI) induced Double Charge Exchange (DCE) reactions. First evidence about the possibility to get quantitative information about NME from experiments is found for the (18O,18Ne) and (20Ne,20O) reactions. Moreover, to infer the neutrino average masses from the possible measurement of the half-life of 0νββ decay, the knowledge of the NME is a crucial aspect. The key tools for this project are the high resolution Superconducting Cyclotron beams and the MAGNEX magnetic spectrometer at INFN Laboratori Nazionali del Sud in Catania (Italy). The measured cross sections are extremely low, limiting 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 foreseen in order to increase the experimental yield of at least two orders of magnitude, thus making feasible a systematic study of all the cases of interest. peerReviewe

Fusion and elastic scattering of

Sub-barrier fusion cross sections (σfus) for the 6Li + 58Ni system, obtained from the respective evaporation protons, are examined in the present work. With respect to expectations of a simple one-dimensional barrier penetration model, a large enhancement of the data is observed. Good consistency with equivalent data reported previously for similar systems is found. A comparison with total reaction cross sections (σR), deduced from elastic scattering measurements reported previously, indicates that σfus is close to σR within the measured energy range. To estimate the contribution of complete fusion (CF), an optical model analysis of the elastic scattering data is performed where CF is identified with the absorption in a short range volume potential. A surface polarization potential is added to the bare nuclear potential to simulate the effect of peripheral reactions. The results obtained indicate that other mechanisms different from CF may be dominant, especially in the lower energy region

Fusion and elastic scattering of 6Li + 58Ni at low energies

Sub-barrier fusion cross sections (σfus) for the 6Li + 58Ni system, obtained from the respective evaporation protons, are examined in the present work. With respect to expectations of a simple one-dimensional barrier penetration model, a large enhancement of the data is observed. Good consistency with equivalent data reported previously for similar systems is found. A comparison with total reaction cross sections (σR), deduced from elastic scattering measurements reported previously, indicates that σfus is close to σR within the measured energy range. To estimate the contribution of complete fusion (CF), an optical model analysis of the elastic scattering data is performed where CF is identified with the absorption in a short range volume potential. A surface polarization potential is added to the bare nuclear potential to simulate the effect of peripheral reactions. The results obtained indicate that other mechanisms different from CF may be dominant, especially in the lower energy region

FUSION OF THE 6Li +58Ni SYSTEM AT SUB-BARRIER ENERGIES

A fusion excitation function for the 6Li +58Ni system was measured at energies near and below the Coulomb barrier. We describe the procedure used to deduce the fusion cross sections from the angular distributions measured for the protons evaporated from the compound nucleus, by using the proton multiplicity predicted by the code PACE2. The comparison of our results with those reported for a very similar system, 6Li +59Co, in reduced units, shows a very good agreement.Se realizó la medición de la función de excitación de fusión para el sistema 6Li +58Ni a energías cercanas a la barrera coulombiana. Se describe el procedimiento usado para deducir las secciones eficaces de fusión a partir de las distribuciones angulares de los protones evaporados del núcleo compuesto, usando la multiplicidad de protón es predicha por el código PACE2. La comparación de nuestros resultados con los reportados para el sistema 6Li +59Co, en unidades reducidas, muestra una buena concordancia

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

The possibility to use a special class of heavy-ion induced direct reactions, such as double charge exchange reactions, is discussed in view of their application to extract information that may be helpful to determinate the nuclear matrix elements entering in the expression of neutrinoless double beta decay half-life. The methodology of the experimental campaign presently running at INFN - Laboratori Nazionali del Sud is reported andthe experimental challenges characterizing such activity are described.European Research Council 71462

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

The possibility to use a special class of heavy-ion induced direct reactions, such as double charge exchange reactions, is discussed in view of their application to extract information that may be helpful to determinate the nuclear matrix elements entering in the expression of neutrinoless double beta decay half-life. The methodology of the experimental campaign presently running at INFN - Laboratori Nazionali del Sud is reported and the experimental challenges characterizing such activity are described

The AMS technique as an important tool for the measurement of astrophysical cross sections

Accelerator Mass Spectrometry is a technique commonly used to approach low concentrations of certain long half-life radioisotopes. The most important contribution of the technique is the accurate measure of organic sample ages, by separating masses 12,13 and 14 in the case of carbon allocated in such samples. However, the reach of AMS could cover many other scientific scopes, since it can give us a precise measure of a very small concentration of a radioisotope. On this direction, AMS can be used to approach reactions of interest for astrophysics, if we spot an specific radioisotope which concentration can be measure with AMS. Starting with this, we have selected specific reactions involving 14C, 10Be and 26Al, produced with slow neutrons from a reactor and positive ions at an accelerator. The main idea is to produce a particular reaction and later to measure the radioisotopic concentration using AMS. In this study our first results for 14C and 10Be nuclei produced with neutrons, and the preliminary results for 26Al nuclei produced with deuterium are shown

The multichannel experimental and theoretical study of the 12^{12}C(18^{18}O,18^{18}F)12^{12}B single charge exchange reaction mechanism

International audienceThe study of a network of nuclear reactions populated in the 18O + 12C collision is the main topic of the present paper. It was performed to test nuclear structure and reaction theories in describing the full reaction mechanism occurring in the (18O, 18F) single charge exchange nuclear reaction. From the experimental side, an 18O beam was produced at 275 MeV incident energy by the K800 superconducting cyclotron and the MAGNEX magnetic spectrometer was used at the Laboratori Nazionali del Sud of the Istituto Nazionale di Fisica Nucleare to momentum analyse the ejectiles produced in the nuclear reactions within the same experimental setup. From the theoretical side, the proposed approach consists of analysing the whole network of nuclear reactions in the framework of a unique comprehensive and coherent theoretical calculation. This holistic approach, applied both to the experimental and theoretical analysis, is the main feature and novelty of the work presented here

Initial State Interaction for the 20^{20}Ne + 130^{130}Te and 18^{18}O + 116^{116}Sn Systems at 15.3 AMeV from Elastic and Inelastic Scattering Measurements

International audienceDouble charge exchange (DCE) reactions could provide experimentally driven information about nuclear matrix elements of interest in the context of neutrinoless double-β decay. To achieve this goal, a detailed description of the reaction mechanism is mandatory. This requires the full characterization of the initial and final-state interactions, which are poorly known for many of the projectile-target systems involved in future DCE studies. Among these, we intend to study the 20Ne + 130Te and 18O + 116Sn systems at 15.3 AMeV, which are particularly relevant due to their connection with the 130Te→130Xe and 116Cd→116Sn double-β decays. We measure the elastic and inelastic scattering cross-section angular distributions and compare them with theoretical calculations performed in the optical model, one-step distorted wave Born approximation, and coupled-channel approaches using the São Paulo double-folding optical potential. A good description of the experimental data in the whole explored range of transferred momenta is obtained provided that couplings with the 21+ states of the projectile and target are explicitly included within the coupled-channel approach. These results are relevant also in the analysis of other quasi-elastic reaction channels in these systems, in which the same couplings should be included