.
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
40
Ca(
18
O,
18
Ne)
40
Ar 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.
This paper reports on elastic scattering excitation functions for the reaction 9Li+4He measured at backward angles in the centre of mass energy range 5 MeV ≤ E≤c.m.9.5 MeV, with the aim of ...investigating the possible existence of molecular resonances which have been predicted to exist in the case of neutron-rich B-isotopes. Due to the short lifetime of 9Li, the experiment necessitated the use of inverse kinematics on a gaseous 4He target. The Thick Target Inverse Kinematics technique was used which allowed for the measurement of the full excitation function in a single 9Li run. Broad resonances were observed in the excitation region for 13B 15 MeV ≤ Ex≤20 MeV. To understand the nature of such broad structures, various theoretical attempts are reported concerning possible reaction mechanisms for this neutron rich reaction. The most promising approach to interpret the data is within the orbiting reaction scenario.
The most promising probe to establish the Majorana or Dirac nature of the neutrino is the neutrinoless double beta decay and the effective neutrino mass would be evaluated by the knowledge of the ...corresponding nuclear matrix elements. Also measurements of the Double Charge Exchange (DCE) interactions of heavy ion beams can get information on them. The NUMEN experiment based on the pre-existing large acceptance MAGNEX spectrometer and integrated with new challenging components aims at measuring DCE cross sections using ion beams of unprecedented intensity (10
13
pps) on specific isotopes at INFN-LNS in Catania. Expected rate on the sensitive area of about 0.15 m
2
reaches up to about 5 Mpps, demanding for adequate detectors in measuring position, direction, energy, mass and charge of the ions produced by interactions. Gamma detectors surround a scattering chamber containing the target.
Precision branching-ratio measurements in 18O Pirrie, S.; Wheldon, C.; Kokalova, Tz ...
The European physical journal. A, Hadrons and nuclei,
2021/4, Letnik:
57, Številka:
4
Journal Article
Recenzirano
Odprti dostop
An experiment has been performed utilising the
12
C(
7
Li,
p
)
18
O reaction to populate high-energy states in
18
O. Using the Munich Q3D magnetic spectrograph in conjunction with the Birmingham ...large-angular-coverage DSSD array, branching ratios have been measured for over fifty states in
18
O, investigating the
α
-decay,
n
-decay, 2
n
-decay and
γ
-decay branches. In tandem, Monte-Carlo techniques have been used to identify and separate features.
The pygmy dipole resonance (PDR) thus far has been described microscopically as a cluster of 1− states around the neutron separation energy (Sn). This study is an attempt to probe the nature of the ...PDR, specifically the single-particle or collective character of these states. One-step transfer reactions represents a good probe for this study due to their selectivity in exciting single-particle states. The 97Mo(p,d) 96Mo and 95Mo(d,p)96Mo reactions, were used to populate the nucleus of interest. The experiment was conducted at the INFN-LNS facility in Catania, Italy. The ejectiles were momentum-analysed by the MAGNEX spectrometer and detected by its focal-plane detector. In this paper, preliminary results for the 97Mo(p, d) 96Mo reaction will be presented.
The experimental set-up of the RIB in-flight facility EXOTIC Pierroutsakou, D.; Boiano, A.; Boiano, C. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
10/2016, Letnik:
834
Journal Article
Recenzirano
Odprti dostop
We describe the experimental set-up of the Radioactive Ion Beam (RIB) in-flight facility EXOTIC consisting of: (a) two position-sensitive Parallel Plate Avalanche Counters (PPACs), dedicated to the ...event-by-event tracking of the produced RIBs and to time of flight measurements and (b) the new high-granularity compact telescope array EXPADES (EXotic PArticle DEtection System), designed for nuclear physics and nuclear astrophysics experiments employing low-energy light RIBs. EXPADES consists of eight ΔE–Eres telescopes arranged in a cylindrical configuration around the target. Each telescope is made up of two Double Sided Silicon Strip Detectors (DSSSDs) with a thickness of 40/60μm and 300μm for the ΔE and Eres layer, respectively. Additionally, eight ionization chambers were constructed to be used as an alternative ΔE stage or, in conjunction with the entire DSSSD array, to build up more complex triple telescopes. New low-noise multi-channel charge-sensitive preamplifiers and spectroscopy amplifiers, associated with constant fraction discriminators, peak-and-hold and Time to Amplitude Converter circuits were developed for the electronic readout of the ΔE stage. Application Specific Integrated Circuit-based electronics was employed for the treatment of the Eres signals. An 8-channel, 12-bit multi-sampling 50MHz Analog to Digital Converter, a Trigger Supervisor Board for handling the trigger signals of the whole experimental set-up and an ad hoc data acquisition system were also developed. The performance of the PPACs, EXPADES and of the associated electronics was obtained offline with standard α calibration sources and in-beam by measuring the scattering process for the systems 17O+58Ni and 17O+208Pb at incident energies around their respective Coulomb barriers and, successively, during the first experimental runs with the RIBs of the EXOTIC facility.
Fluorine abundance determination is of great importance in stellar physics to understand s-elements production and mixing processes in asymptotic giant branch (AGB) stars. Up to now, theoretical ...models overproduce F abundances in AGB stars with respect to the observed values, thus calling for further investigation of the reactions involving fluorine. In particular, the 19F(p, )16O reaction is the main destruction channel of fluorine at the bottom of the convective envelope in AGB stars, an H-rich environment where it can experience temperatures high enough to determine its destruction, owing to additional mixing processes. In this paper the Trojan horse method (THM) was used to extract the 19F(p, 0)16O S-factor in the energy range of astrophysical interest (Ecm 0-1 MeV). This is the most relevant channel at the low temperatures (few 107 K) characterizing the bottom of the convective envelope, according to current knowledge. A previous indirect experiment using the THM has observed three resonances in the energy regions below Ecm 450 keV. These energies correspond to typical AGB temperatures, thus implying a significant increase in the reaction rate. Statistics are scarce for performing an accurate separation between resonances, preventing one from drawing a quantitative conclusion about their total widths and spin parities. Before THM measurement, only extrapolations were available below about 500 keV, showing a non-resonant behavior that sharply contradicts the trend of the astrophysical factor at higher energies. A new experiment has been performed to verify the measured TH astrophysical factor and to perform more accurate spectroscopy of the involved resonances.
The 4He(4He,4He)4He* inelastic scattering was investigated at the MAGNEX facility of INFN - LNS, aiming at shedding light on the characteristics of the isoscalar monopole resonance of 4He which lies ...at an energy slightly higher than the proton emission threshold and slightly lower than the neutron emission threshold. A complementary elastic scattering measurement was also performed to study the initial state interaction and set accurate coupled channel calculations. Here, the experimental setup, the data reduction and the theoretical interpretation strategy are briefly described.
Abstract
Double charge exchange (DCE) reactions induced by heavy ions are crucial tools to access information relevant for neutrinoless double beta decay nuclear matrix elements. In this context the ...NUMEN project aims to investigate, for each system of interest, the DCE reaction channel together with the whole set of reactions promoted by the same projectile/target interaction in the same experimental conditions and within the same theoretical framework.
PDF
