This article presents the main achievements of the NUMEN project, together with an updated and detailed overview of the associated R D activities and theoretical advances. It essentially represents the second edition of the review article [Eur. Phys. J. A 54 (2018) 72], with a particular focus on the most significant results obtained in recent years.NUMEN is primarily devoted to the investigation of nuclear double charge exchange (DCE) reactions induced in heavy-ion collisions at beam energies above the Coulomb barrier. These reactions are of great interest for exploring the largely unexplored rank-2 isotensor effects in bound nuclear systems under controlled laboratory conditions.Within this context, NUMEN introduces a promising approach to access the nuclear matrix elements (NMEs) that govern the lifetime of neutrinoless double beta decay (0 νββ ).The article reports detailed aspects of the theoretical framework developed by the NUMEN collaboration to extract the relevant nuclear structure information from measured DCE cross sections. The first experimental measurements carried out at the INFN-LNS laboratory have provided encouraging evidence of the method’s potential to yield quantitative information relevant to 0 νββ -decay NMEs. Nevertheless, the extremely small values of the DCE cross sections, combined with the stringent resolution requirements, have necessitated a major upgrade of the INFN-LNS infrastructure to achieve luminosities far exceeding those previously attainable. The ongoing upgrade program, carried out within the NUMEN project to meet these demanding requirements, is also discussed in the article.

The NUMEN (NUclear Matrix Elements for Neutrinoless double beta decay) project at INFN-Laboratori Nazionali del Sud aims to extract quantitative information on the Nuclear Matrix Elements relevant to neutrinoless double beta decay, a key process for determining whether the neutrino is a Majorana or Dirac particle and for establishing its effective mass. This objective will be pursued by measuring the cross sections of double charge exchange reactions induced by intense heavy-ion beams on selected isotopes that are candidates for neutrinoless double beta decay. The need to measure extremely low cross sections with high statistical significance has driven a major upgrade of the entire INFN-LNS infrastructure, enabling the production of heavy-ion beams with intensities up to 1013 pps at the position of the experimental target. Additionally, significant enhancements are being made to the focal plane detectors of the existing MAGNEX spectrometer. A new target system and advanced detectors are under development to track and identify heavy ions at an expected rate of 5×106 Hz at full beam intensity, while also allowing γ-ray detection. This contribution provides an overview of the current status of the NUMEN project, highlighting recent developments and characterization campaigns for nuclear targets and detector systems.

The upgrade project POTLNS to produce high-intensity beams has already started at INFN- Laboratori Nazionali del Sud in Catania (Italy). The POTLNS project was triggered by the NUMEN physics case that aims to provide experimental information on the Nuclear Matrix Elements (NMEs) that enter in the expression of the neutrino-less double beta (0νββ) decay half-life. The tools proposed by NUMEN project are the cross-section measurements of nuclear Double Charge Exchange (DCE) reactions. The search for 0νββ decay is currently a key topic in physics, due to its possible wide implications for nuclear physics, particle physics and cosmology: the NUMEN project could provide a crucial contribution in this search.

The radiation damage in optical materials mostly manifests itself as the loss of optical transmission. The optical materials recover from radiation damage to some extent in the presence of natural light, and at a faster rate in the presence of stimulating light. On the other hand, the systematic study of the dynamics of the recovery as a function of the stimulating light parameters such as its wavelength, intensity and exposure duration and method has not been performed in detail. We established an LED recovery station which provides pulsed and continuous light at various wavelengths at custom geometries. The study starts with the irradiation of optical samples at various gamma doses at a rate of 87.5 Gy/min. The optical transmittance of the samples are then measured in 200 nm - 1500 nm range for an extended period of time. Here we report on the details of the irradiation and recovery setups, and the results of recovery from radiation damage under different light exposure mechanisms.

we conduct a more realistic double-folding numerical treatment of the Coulomb potential in comparison with the usual analytical approximation for the different prescriptions of nuclear radius. By using this double-folding technique, we present that a superior approximation to the standard analytical rigid spheres one could be achieved. The results illustrating the differences for the extensively studied ^16 O + ^208 Pb system are presented. It is observed that the potential for the short-ranges, which one expects to be below or up-to the barrier, the analytical approximations are inferior to the double-folding procedure, especially so for the simplest radius choice. Our results clearly show that the analytical approaches are rather poor and the use of the double-folding technique for the Coulomb potential will lead to a better determination of the nuclear potential for the interaction of two nuclei.

The use of 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 strategy adopted in the experimental campaigns performed at INFN - Laboratori Nazionali del Sud and in the analysis methods within the NUMEN project is briefly described, emphasizing the advantages of the multi-channel approach to nuclear reaction data analysis. An overview on the research and development activities on the MAGNEX magnetic spectrometer is also given, with a focus on the chosen technological solutions for the focal plane detector which will guarantee the performances at high-rate conditions.

The radiation damage in the optical active media of collider detectors and beamline instrumentation is an outstanding problem. The exposed doses reach unprecedented levels in some current and projected implementations. In order to mitigate this, the development of optical materials with higher radiation resistance is underway. On the other hand, there is a significant lack of in-situ radiation damage recovery systems, whereas such systems have the potential to increase the useful lifetime of the optical materials considerably. Although it is well-known that stimulating the recovery of radiation damage with LED illumination significantly improves the recovery rate and the ultimate damage, a systematic study of the recovery e.g. as a function of the incident LED light spectra, intensity and exposure duration has not been performed. Here we attempt to do this study and present our first results of recovery from radiation damage under different recovery conditions.

In this study we have used a beam generated by a clinical linac to activate an Indium sample. The beam used was generated by electrons of 18 MeV impacting on a tungsten target. The beam was mainly composed of bremsstrahlung photons with a small admixture of neutrons. The gamma-ray spectrum of the sample was recorded with a HPGe in an offline setup. Here we present the values obtained from the analysis of the spectrum. Both transition energies of several Indium isotopes as well as half-lives of some of them were obtained. The results shown were compared to the literature values. In majority of the cases there is good agreement and in some case we see significant improvement of uncertainties for transition energies. We have also measured the transition energies and half-lives of Scandium, Antimony, Bromine, Chlorine, Gallium and Praseodymium nuclei experimentally by photonuclear reaction and further results will be submitted for the publication.

The bremsstrahlung photons of 18MeV end-point energy produced by a clinical linear accelerator were used to irradiate (93)Nb, producing (92m)Nb via the photonuclear reaction. The gamma-ray spectrum emitted by the excited nucleus was measured with high purity germanium detector. For analysis of the energy transitions, both gf3 and ROOT spectrum analysis programs were applied. The results were shown to be comparable with the literature values, demonstrating the ability to use a clinical liner accelerator in nuclear physics measurements.

It is possible to excite atomic nuclei electromagnetically and even separate proton or neutron from a sample which is exposed to gamma rays by a clinical linac. Thus, the determination of the elemental concentration of a sample by photo-activation analysis is a reasonable attempt since it is related to the detailed analysis of the photonuclear reaction of an intended element. In this study, in order to get the proof of principle for photo-activation a titanium dioxide and a 10 kurus Turkish coin samples are irradiated with high energy bremsstrahlung photons at the end-point energy of 18 MeV and their zinc and copper concentrations are determined by a precise measurement with a high purity germanium detector.

We have run an experiment to determine the energy levels and half-lives of Gallium nucleus by using the photonuclear reactions with end-point energy of 18 MeV bremsstrahlung photons, produced by a clinical linear accelerator. As a result of 71Ga(y,n)70Ga and 69Ga(Y,n)68Ga photonuclear reactions, the energy levels and half-lives of 70Ga and 68Ga nuclei have been determined. The results are in good agreement with the literature values.

In this paper, a meteorite sample provided from TUBITAK National Observatory found in Turkey has been investigated by using a clinical linear accelerator that has endpoint energy of 18 MeV, and a high purity Germanium detector for qualitative elemental analysis within photo-activation analysis method. 21 nuclei ranging from Na-24 to Nd-149 have been identified in the meteorite sample.

The spectrum of the 238U(γ, f) photofission reaction which is obtained using bremsstrahlung photon beams from a clinical e-linac is analyzed. The following nuclei 94Y, 134Te, 136Pr, 142Ba, 138Xe, 104Tc in the spectrum of our experiment have been identified. The gamma ray energies of the produced nuclei are compared with the literature values. This work is a proof-of-concept experiment which is the first of in the series of our future planned photofission experiments using a clinical e-linac operated with different endpoint energies.

The use of bremsstrahlung photons produced by a linac to induce photonuclear reactions is wide spread. However, using a clinical linac to produce the photons is a new concept. We aimed to induce photonuclear reactions on zinc isotopes and measure the subsequent transition energies and half-lives. For this purpose, a bremsstrahlung photon beam of 18MeV endpoint energy produced by the Philips SLI-25 linac has been used. The subsequent decay has been measured with a well-shielded single HPGe detector. The results obtained for transition energies are in good agreement with the literature data and in many cases surpass these in accuracy. For the half-lives, we are in agreement with the literature data, but do not achieve their precision. The obtained accuracy for the transition energies show what is achievable in an experiment such as ours. We demonstrate the usefulness and benefits of employing clinical linacs for nuclear physics experiments.

Background: Inelastic neutrino-nucleus scattering through the weak neutral-current plays an important role in a stellar environment where the transport of neutrinos determines the rate of cooling. Since there are no direct experimental data on neutral-current neutrino-nucleus cross sections available, only the modeling of these reactions provides the relevant input for supernova simulations.Purpose: To establish a fully self-consistent framework for neutral-current neutrino-nucleus reactions based on a relativistic nuclear energy density functional.Methods: Neutrino-nucleus cross sections are calculated using a weak Hamiltonian and nuclear properties of initial and excited states are obtained with a relativistic Hartree-Bogoliubov model and a relativistic quasiparticle random phase approximation that is extended to include pion contributions for unnatural parity transitions.Results: Inelastic neutral-current neutrino-nucleus cross sections for C-12, O-16, Fe-56, Ni-56, and even isotopes Mo92-100 as well as respective cross sections averaged over distribution of supernova neutrinos.Conclusions: The present study provides insight into neutrino-nucleus scattering cross sections in the neutral channel, their theoretical uncertainty in view of recently developed microscopic models, and paves the way for systematic self-consistent large-scale calculations involving open-shell target nuclei.

In this paper, we study the connection between the interaction and the low energy observables, in particular the cross section for He and HeX, the helium nucleus with a heavier particle attached, to explain problems with the observed lithium abundance in the big-bang nucleosynthesis. We treat the processes He-4 + H-2 -> Li-6 + gamma and (HeX-)-He-4 + H-2 -> Li-6 + X- and primarily focus on the effects of the long-range part of the total potential on the cross section. Our results indicate that relatively small changes in the long-range part of the potential can have a profound affect. Additionally, we compare the relative impacts on the low energy cross section of the Coulomb barrier peak and the long-range part of the interaction. Our results confirm that the long-range potential dominantly influences the low energy observables.

The problem of the observed lithium abundance coming from the Big Bang Nucleosynthesis is as of yet unsolved. One of the proposed solutions is including relic massive particles into the Big Bang Nucleosynthesis. We investigated the effects of such particles on (HeX-)-He-4 + H-2 -> Li-6 + X-, where the X- is the negatively charged massive particle. We demonstrate the dominance of long-range part of the potential on the cross-section.

By employing a recently constructed hyperon-nucleon potential the equation of state of beta-equilibrated and charge neutral nucleonic matter is calculated. The hyperon-nucleon potential is a low-momentum potential which is obtained within a renormalization group framework. Based on the Hartree-Fock approximation at zero temperature the densities at which hyperons appear in neutron stars are estimated. For several different bare hyperon-nucleon potentials and a wide range of nuclear matter parameters it is found that hyperons in neutron stars are always present. These findings have profound consequences for the mass and radius of neutron stars.

Single-particle potentials in Hartree-Fock approximation for different hyperon-nucleon (Y N) channels are calculated in the framework of the effective low-momentum Y N interaction V-low k. In contrast to the nucleon-nucleon interaction, the available experimental data for the Y N interaction are scarce. As a consequence, no unique Y N low-momentum potential V-low k can be predicted from the various bare potentials. The resulting momentum-and density-dependent single-particle potentials for several different bare OBE models and for chiral effective field theory are compared to each other.