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The present paper is focused on our recent efforts to study the production and identification of neutron-rich medium-mass rare isotopes from peripheral reactions at beam energies around and below the Fermi energy. We obtained high-quality experimental data from a recent experiment with the MAGNEX spectrometer at the INFN-LNS in Catania, Italy. The main aim of this experiment was to check the feasibility of ejectile identification in this energy regime with the use of a large acceptance magnetic spectrometer. Our developed technique for particle identification depends mainly on a reconstruction of both the atomic number Z and the ionic charge q of the ions, followed by the identification of the mass. Our method was successfully applied to identify neutron-rich ejectiles from multinucleon transfer from the reaction of 70Zn (15 MeV/nucleon) + 64Ni. Preliminary results indicate that the extracted experimental distributions, along with comparisons with the theoretical models could help us to shed light to the complex reaction mechanism of multinucleon transfer in this energy regime.

The present work is focused on our efforts to produce and identify neutron-richrare isotopes from peripheral reactions below the Fermi energy. High-quality experimental data were obtained from a recent experiment with the MAGNEX spectrometer at INFN-LNS in Catania, Italy. The main goal of this effort is to describe the adopted identification techniques used to analyze the data from the reaction 70 Zn (15 MeV/nucleon) + 64 Ni. The particle identification procedure is based on a novel approach that involves the reconstruction of both the atomic number Z and the ionic charge q of the ions, followed by the identification of themass. Our method was successfully applied to identify neutron-rich ejectiles from multinucleon transfer in the above reaction 70 Zn + 64 Ni at 15 MeV/nucleon. The analysis of the data is ongoing. We expect to obtain the angular and momentum distributions of the fragments, along with their production cross sections. These data, along with comparisons with theoretical models are expected to contribute to a better understanding of the complex reaction mechanisms of multinucleon transfer that dominate this energy regime.

The goal of limiting the use of natural resources and combatting climate change has led to the improvement of agricultural techniques and the development of some Carbon Dioxide Removal (CDR) techniques, given their proficiency to sequester carbon from the atmospheric CO2 and to store it in more stable forms within oceans, plants, soil, or other terrestrial environments. Among them, Enhanced Weathering (EW) is regarded as one of the most promising. This consists of amending soils with silicate minerals, such as olivine, so as to speed up the weathering process that naturally occurs in soils. This work aims to couple a model for the resolution of the agro-hydrological balance in the active soil layer of croplands (i.e., WATNEEDS model) and a dynamic mass balance model that explores ecohydrological, biogeochemical, and olivine dissolution dynamics, also estimating carbon sequestration rates (i.e., EW model). This latter is composed of different interacting components and takes into account important processes, such as the cation exchange.From the operational point of view, the EW model is fed by rainfall data, and the outputs of the soil water balance (i.e., infiltration, evapotranspiration, leaching, and runoff rates) estimated by the WATNEEDS at the global scale at a 5 arcminute resolution. In this study, a regional application of both models is proposed to explore EW efficiency in various cropland areas in Sicily (Italy), the largest island of the Mediterranean basin, which is considered a hot spot of climate change. The methodological approach will be developed and tested for four different crops (i.e., olive and citrus groves, vineyards, and fruit trees) that are particularly widespread and profitable in the selected region. Apart from facing climate change, the goal of this study is also to preserve water, thus selecting the most suitable irrigation strategies in the context of a changing climate and olivine amendment prescription. This study may also provide a tool to decision-makers for an actual future application of EW, which can be valid for Sicily and for other parts of the world with similar climatic conditions, soil, and vegetation.

Enhanced weathering (EW) is a promising strategy for carbon sequestration, but several open questions remain regarding the actual rates of dissolution in conditions of natural hydroclimatic variability in comparison to laboratory experiments. In this context, models play a pivotal role, as they allow exploring and predicting EW dynamics under different environmental conditions. Here a comprehensive hydro-biogeochemical model has been applied to four cropland case studies (i.e., Sicily and the Padan plain in Italy and California and Iowa in the USA) characterized by different rainfall seasonality, vegetation (i.e., wheat for Sicily and California and corn for the Padan plain and Iowa), and soil type to explore their influence on dissolution rates. The results reveal that rainfall seasonality and irrigation when applied are crucial in determining EW and carbon sequestration dynamics, given their effect on hydrological fluxes, soil pH and weathering rate. The carbon sequestration rate was found to be strongly affected also by the background weathering flux, which is one of the main factors controlling soil pH before the olivine amendment. Regarding the US case studies, Iowa sequesters the greatest amount of CO2 if compared to California (4.20 and 2.21 kg ha−1 yr−1, respectively), and the same happens for Sicily with respect to the Padan plain (0.62 and 0.39 kg ha−1 yr−1, respectively). These low carbon sequestration values suggest that an in-depth analysis at the global scale is required to assess EW efficacy for carbon sequestration.

The impacts of climate change, mainly due to the use of fossil fuels, have been rising over the last decades. To address this problem, the scientific community is currently making a big effort, coming up with several solutions aiming to reduce greenhouse gas emissions or to sequester the carbon within the atmospheric CO2.In this context, Enhanced chemical weathering is included in the group of carbon sequestration technologies. These techniques involve removing CO2 from the atmosphere and storing the carbon within it in the oceans, terrestrial environments or geologic formations. The natural chemical weathering is the main process of soil formation, since it is the ensemble of the chemical/biochemical reactions leading to the alteration of primary minerals, thus to the formation of secondary minerals. The Enhanced chemical weathering consists of increasing the natural weathering reaction rates, by adding some highly reactive minerals to the soil. It is widely known that weathering rates are higher under warm and humid climate conditions and high soil acidity.The present study evaluates the effects of Forsterite, a common silicate mineral also known as Mg-olivine, on soil carbon sequestration. This mineral is recognized by many studies as the best solution for Enhanced weathering applications since it is available in many parts of the world and its reaction rates with CO2 are much higher than those of other minerals. In this study, a model simulating the dynamics of the biogeochemistry of a soil treated with olivine under different climate scenarios is presented. The model is forced by a stochastic rainfall, simulated as a marked Poisson process, and puts together the ecohydrology and the biogeochemistry. Plants influence the whole system with their evapotranspiration, nutrients uptake (Na+, Ca2+ and Mg2+) and the addition of organic matter to the soil. Biogeochemistry involves all the aspects of the model related to the cycle of the dissolved ions (H+, Na+, Ca2+ and Mg2+), litter decomposition and the chemical reaction of olivine with CO2.Running the model under different climate scenarios highlights that the highest olivine weathering rates are assessed under wet conditions. This happens because high soil moisture leads to higher reactive surface areas of particles and higher dissolution rates. This aspect is emphasized from the fact that soil pH is lower in humid than in dry environments and weathering reaction rates are higher in acid conditions since hydrogen ions are the reactants of many weathering reactions. The study also attempts to evaluate the economic feasibility of the intervention in agricultural fields. Apart from the costs of performing this kind of intervention, some benefits should be taken into account. More specifically, spreading olivine on agricultural fields leads to an increase of Na+, Ca2+ and Mg2+ concentrations, thus a certain amount of olivine can replace the addition of fertilizers. Therefore, this study proposes a natural solution for facing climate change problems and presents a model that could be used as a decision support system in land management.

Climate change and unsustainable land management practices have resulted in extensive soil degradation, including alteration of soil structure (i.e., aggregate and pore size distributions), loss of soil organic carbon, and reduction of water and nutrient holding capacities. Although soil structure, hydrologic processes, and biogeochemical fluxes are tightly linked, their interaction is often unaccounted for in current ecohydrological, hydrological and terrestrial biosphere models. For more holistic predictions of soil hydrological and biogeochemical cycles, models need to incorporate soil structure and macroporosity dynamics, whether in a natural or agricultural ecosystem. Here, we present a theoretical framework that couples soil hydrologic processes and soil microbial activity to soil organic carbon dynamics through the dynamics of soil structure. In particular, we link the Millennial model for soil carbon dynamics, which explicitly models the formation and breakdown of soil aggregates, to a recent parameterization of the soil water retention and hydraulic conductivity curves and to soil carbon substrate and O2 diffusivities to soil microsites based on soil macroporosity. To illustrate the significance of incorporating the dynamics of soil structure, we apply the framework to a case study in which soil and vegetation recover over time from agricultural practices. The new framework enables more holistic predictions of the effects of climate change and land management practices on coupled soil hydrological and biogeochemical cycles.

Enhanced weathering (EW) is one of the most promising technologies for sequestering atmospheric carbon. It consists on accelerating the chemical weathering fluxes naturally occurring in soils, by means of the addition of silicate minerals (i.e., forsterite), used as amendments, to the soil. If crushed into micrometer-sized particles, these minerals are characterized by high dissolution rates, that may be further improved under high soil water content and low pH conditions. Before actually applying EW technique at the global scale for carbon sequestration, an in-depth characterization of weathering and carbon sequestration rates, under different environmental conditions, is needed, also looking at correlated beneficial/detrimental effects. In this context, modeling approaches may play a pivotal role, since they allow to achieve this goal without affording costs required by laboratory and field experiments. The present study describes the application of a dynamic mass balance model connecting ecohydrological, biogeochemical and olivine dissolution dynamics. The model is composed of four connected components and is solved through an explicit system of eight mass balance total differential equations and an implicit one having 22 algebraic equations.In this study, the model is applied to two sites in Italy (i.e., Sicily, in the south and the Padan plain, in the north) and two in the USA (i.e., California, in the south-west and Iowa, in the north-central area). The most common crops for the case studies, i.e., wheat for Sicily and California and corn for the Padan plain and Iowa are here considered, along with the most frequent soil types, namely the clay loam for Sicily and California and the silty clay loam for the Padan plain and Iowa. Maps of lithological composition of bedrocks and spatial distributions of soil pH have been also used to calibrate the background weathering flux, responsible of the H+ consume from all the minerals naturally present in the soil. Apart from deriving the most suitable locations, among those presented, providing the highest weathering and carbon sequestration rates, these simulations allow to assess the role of different climate, crop and soil types on EW dynamics, in perspective to find the combination that maximizes the CO2 sequestration.

Soil carbon cycling and ecosystem functioning can strongly depend on how microbial communities regulate their metabolism and adapt to changing environmental conditions to improve their fitness. Inv...

Enhanced weathering (EW) is one of the most promising negative emissions technologies urgently needed to limit global warming to at least below 2 °C, a goal recently reaffirmed at the UN Global Climate Change conference (i.e., COP26). EW relies on the accelerated dissolution of crushed silicate rocks applied to soils and is considered a sustainable solution requiring limited technology. While EW has a high theoretical potential of sequestering CO2, research is still needed to provide accurate estimates of carbon (C) sequestration when applying different silicate materials across distinct climates and major soil types in combination with a variety of plants. Here we elaborate on fundamental advances that must be addressed before EW can be extensively adopted. These include identifying the most suitable environmental conditions, improving estimates of field dissolution rates and efficacy of CO2 removal, and identifying alternative sources of silicate materials to meet future EW demands. We conclude with considerations on the necessity of integrated modeling–experimental approaches to better coordinate future field experiments and measurements of CO2 removal, as well as on the importance of seamlessly coordinating EW with cropland and forest management.

Aiming at facing climate change, some CDR (Carbon Dioxide Removal) techniques are currently studied given their capability to sequester carbon from the atmospheric CO2 and to store it within oceans, plants, soil, or other terrestrial environments. Among them, Enhanced Weathering (EW), that acts in speeding up the chemical weathering naturally occurring in soils through the amendments of highly reactive silicate minerals, is referred to as one of the most promising. Hot and humid climates provide the best conditions for EW, since reactions are faster at high temperature, high soil water content and low soil pH. This study presents a dynamic mass balance model that explores ecohydrological, biogeochemical and olivine dissolution dynamics. Through the application of this model, which is composed of different interconnected components, it is possible to explore the role of hydrological processes on olivine dissolution and, therefore, to compute carbon sequestration rates. The model is coupled with a spatially distributed crop specific agro-hydrological model named WATNEEDS, able to solve the soil water balance at the global scale at a 5 arcminute resolution. Input of rainfall data, along with the outputs components of the soil water balance (i.e., infiltration, evapotranspiration, leaching and runoff rates) for each crop, estimated the WATNEEDS are used as input in estimating EW yields at large scale. Here a current application at the regional scale for agriculture, is proposed to explore EW yields in various cropland areas in Italy. The spatial extension of the study area, i.e., the whole Italian territory, allows to explore the EW dynamics under different climate conditions and crop and soil types, defining the importance of such factors in the EW dynamics. This allows to extract olivine dissolution dynamics in places characterized by significant differences in terms of rainfall seasonality, crop phenology, soil type and composition. A future enhancement of this study may be the application of the EW model at the global scale, so as to provide a tool to decision makers for an actual future application of EW.

Enhanced Weathering (EW) is a promising strategy for carbon sequestration, but several open questions remain regarding the actual rates of dissolution in conditions of natural hydroclimatic variability in comparison to laboratory experiments. In this context, models play a pivotal role, as they allow exploring and predicting EW dynamics under different environmental conditions. Here a comprehensive hydro-biogeochemical model has been applied to four cropland case studies (i.e., Sicily and the Padan plain in Italy and California and Iowa in the USA) characterized by different rainfall seasonality, vegetation (i.e., wheat for Sicily and California and corn for Padan plain and Iowa), and soil type to explore their influence on dissolution rates. The results reveal that rainfall seasonality, and irrigation when applied, are crucial in determining EW and carbon sequestration dynamics, given their effect on hydrological fluxes, soil pH, and weathering rate. The carbon sequestration rate was found to be strongly affected also by the pre-EW soil pH, which is one of the main factors controlling soil pH before the olivine amendment. In the analyzed case studies, Iowa and Sicily sequester the greatest amount of CO2 (4.20 and 0.62 kg ha-1 y-1, respectively), as compared to California and the Padan plain (2.21 and 0.39 kg ha-1 y-1, respectively). These low carbon sequestration values suggest that an in-depth analysis at the global scale is required to assess EW efficacy for carbon sequestration.

With the aim to face climate change, some NCS (Natural Climate Solutions) are currently studied given their capability to sequester carbon from the atmospheric CO2, by means of some natural processes, and to store it within oceans, plants, soil, or other terrestrial environments. Among all the existing NCS, Enhanced Weathering (EW) acts in speeding up the chemical weathering that naturally occurs in soils. This is achieved by amending soils with crushed highly reactive silicate minerals, such as forsterite, better known as olivine. In general, EW reactions are faster at high temperature and soil water content and low soil pH, demonstrating that the most suitable places in the world to apply this technique are those characterized by hot and humid climates. Vegetation has a positive effect for EW reactions, given its acidifying action on soil water, due to the displacement of H+ ions consequent to the uptake of cations used as nutrients (i.e., Mg2+, Ca2+ and K+). Furthermore, it has been demonstrated that olivine dissolution leads to the increase of the above-listed nutrients concentration in soil water, resulting in a fertilizing effect for plants. For these reasons, various studies affirm that it may be realistic to apply EW technique in forested or cultivated areas, but only after reliably quantifying its carbon sequestration rate and other beneficial/detrimental effects. This study presents a dynamic mass balance model that explores ecohydrological, biogeochemical and olivine dissolution dynamics. The model allows to explore the role of hydrological processes on long term olivine dissolution and, therefore, to compute carbon sequestration and the increase of nutrients in soil water upon olivine dissolution. The model is composed of different interconnected components and the resulting scheme consists of an explicit system of eight mass balance total differential equations and an implicit part with 22 algebraic equations in as many unknown variables. The main purpose of the present study is to apply the model to two different sites in Italy (i.e., Sicily, in the south and the Padan plain, in the north) and two other sites in the USA (i.e., California, in the south-west and Iowa, in the north-central area). Furthermore, crops that are very common and occupy a huge area in correspondence of the considered sites, namely the wheat crop for Sicily and California and the corn crop for Padan plain and Iowa, are here taken into account. This allows to explore the EW dynamics under different climate conditions and crop and soil types, with the aim to assess the importance of such factors in the EW application. This study could be helpful for decision makers to identify which parts of the globe, among those presented, are more suitable for amending soil with olivine, in perspective to put EW into practice.

Soil heterotrophic respiration (R(h)) represents an important component of the terrestrial carbon cycle that affects whether ecosystems function as carbon sources or sinks. Due to the complex interactions between biological and physical factors controlling microbial growth, R(h) is uncertain and difficult to predict, limiting our ability to anticipate future climate trajectories. Here we analyze the global FLUXNET 2015 database aided by a probabilistic model of microbial growth to examine the ecosystem-scale dynamics of R(h) and identify primary predictors of its variability. We find that the temporal variability in R(h) is consistently distributed according to a Gamma distribution, with shape and scale parameters controlled only by rainfall characteristics and vegetation productivity. This distribution originates from the propagation of fast hydrologic fluctuations on the slower biological dynamics of microbial growth and is independent of biome, soil type, and microbial physiology. This finding allows us to readily provide accurate estimates of the mean R(h) and its variance, as confirmed by a comparison with an independent global dataset. Our results suggest that future changes in rainfall regime and net primary productivity will significantly alter the dynamics of R(h) and the global carbon budget. In regions that are becoming wetter, R(h) may increase faster than net primary productivity, thereby reducing the carbon storage capacity of terrestrial ecosystems.

The 130Te(20Ne,20O)130Xe double charge exchange reaction was measured for the first time at very forward angles with the MAGNEX magnetic spectrometer at INFN-LNS. The study, performed at beam energy of 306 MeV, is part of a systematic exploration promoted by the NUMEN project. The last aims to measure specific reaction cross sections to provide experimentally driven information about nuclear matrix elements of interest in the context of neutrinoless double beta decay.

To mitigate global warming, a noticeable research effort is being devoted to NCS (Natural Climate Solutions) as means to reduce greenhouse gas emissions or sequester carbon within the oceans or terrestrial environments by exploiting natural processes. Enhanced weathering is a NCS that aims to increase the weathering reaction rates of silicate minerals, by amending soils with crushed reactive minerals. Various studies have shown that this technique is favored by hot and humid climates (i.e., tropical ecosystems), since weathering reactions are mostly effective under high temperature and soil moisture. Despite olivine dissolution dynamics in laboratory conditions are quite well known, understanding and modeling them in field is still a challenge. Indeed, apart from some pot experiments involving soils of agricultural fields, only few weathering models are available. Given the urgency of the problem, models play a very important role for extrapolating results of laboratory and field experiments in both time and space, as well as for quantifying the impact of hydroclimatic fluctuations on the involved biogeochemical processes.The present study explores the role of hydrological processes on long-term Forsterite dissolution, a highly reactive silicate mineral also known as Mg-olivine or simply olivine. Toward this goal, we present a novel dynamic mass balance model coupling ecohydrological and biogeochemical dynamics, including mineral dissolution. Results under different climate scenarios highlight that hydrological fluctuations lead to hysteretic patterns of weathering rate with soil moisture, meaning that the process maintains a memory of past events (i.e., dry or wet periods). The model allows to explore the twofold role of organic matter on enhanced weathering; indeed, while its decomposition is a source of CO2, organic matter also increases the soil CEC, thus buffering changes in soil pH. Carbon sequestration and nutrients availability due to enhanced weathering are quantified, in this study, as a function of MAP (Mean Annual Precipitation). Average CO2 that reacts with olivine can exceed 40 t ha-1 y-1 for MAP higher than 2000 mm, condition that is always reached in the tropics. This CO2 can be found as dissolved in soil water in the form of bicarbonate (HCO3-) and carbonate (CO32-) ions and will be leached away from the domain, eventually reaching the ocean. In presence of tropical climate olivine application also leads to an increase of soil pH and nutrients availability, especially calcium and magnesium, which in turn can enhance plant productivity. This study paves the way for a potential integration of enhanced weathering in agroecosystem management practices, especially in humid tropical regions since these are characterized by high MAP and temperature.

Natural climate solutions are attracting considerable research effort with the aim of reducing greenhouse gas emissions or sequestering carbon within the oceans or terrestrial environments. In this context, enhanced weathering can be a powerful means of increasing the natural weathering reaction rates, by adding some highly reactive minerals to the soil. The present study evaluates the effects of hydrologic fluctuations on Forsterite dissolution, a silicate mineral also known as Mg-olivine. This mineral is available in many parts of the world and its reaction rates with CO2 are much higher than those of other minerals. Toward this goal, we developed a mathematical model coupling biogeochemical and ecohydrological aspects of a soil treated with olivine. The model can be forced with a stochastic rainfall, in order to understand the role of hydrological processes on long-term enhanced weathering dynamics. The results under different climate scenarios quantify the dependence of weathering rates on wetness. High soil water contents are linked to higher reactive surface area and lower pH levels, resulting in higher dissolution rates. The weathering rate shows a hysteretic behavior with respect to soil moisture since its variability does not immediately lead to a change in weathering rate. Plants play a relevant role in this context since they may further increase the weathering rate by releasing H+ ions in soil water. In addition, we explore the twofold role of organic matter on enhanced weathering; while its decomposition is a source of CO2, organic matter also increases the soil CEC, thus buffering changes in soil pH. In conclusion, by shedding light on the interaction between olivine dissolution and ecohydrological processes, this study paves the way for the inclusion of enhanced weathering in agroecosystem management practices.

International audience; 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 strategies adopted in the experimental campaigns performed at INFN - Laboratori Nazionali del Sud are briefly described, emphasizing the advantages of the multi-channel approach to nuclear reaction data analysis.

Two-nucleon transfer reactions are essential tools to investigate specific features of the nuclear structure, such as the correlation among valence particles in the transfer process. Besides, transfer reactions may be an important channel to take into account in charge-exchange processes since they can represent a competing contribution to the final cross section. The two-proton pickup transfer reaction $^{40}\mathrm{Ca}(^{18}\mathrm{O},^{20}\mathrm{Ne})\phantom{\rule{0.16em}{0ex}}^{38}\mathrm{Ar}$ has been measured at 270 MeV, and the angular distributions for transitions to different excited states extracted. This paper shows the analysis of the data performed by finite-range coupled reaction channel and coupled-channel Born approximation methods. Extensive shell-model calculations are performed to derive the one- and two-proton spectroscopic amplitudes for the projectile and target overlaps. The role of the simultaneous and sequential two-proton transfer mechanisms to populate the measured final states or groups of states, mainly characterized by a high collectivity, is also discussed.

It is well known that evaporative cooling of Earth's surface water reduces the amount of radiation that goes into sensible heat, namely the portion of radiation that produces higher temperatures. However, a rigorous use of long-term hydrologic measurements and the related theories of hydrologic partitioning have not yet been fully exploited to quantify these effects on climate. Here, we show that the Budyko's curve, a well-known and efficient framework for water balance estimation, can be effectively utilized to partition the surface energy fluxes by expressing the long-term evaporative fraction as a function of the dryness index. The combination of this energy partitioning method with hydrological observations allows us to estimate the surface energy components at watershed and continental scales. Analyzing climate model outputs through this new lens reveals energy biases due to inaccurate parameterization of hydrological and atmospheric processes, offering insight into model parameterization and providing useful information for improving climate projections.

Because of its interaction with plants, carbon decomposition, and soil properties, soil iron cycle has been recognized as an important player in the carbon and other biogeochemical cycles. The impact of the hydrologic cycle and plants on it, however, remains largely unexplored. Here we focus on terrestrial ecosystems and develop a dynamical system to analyze the coupling between iron and carbon dynamics in the soil root zone as driven by fluctuations in soil moisture. Particular emphasis is placed on the modeling of the soil organic matter, the Fe-reducing population, the iron Fe2+-Fe3+ cycling, and the soil moisture level, which controls the redox rates. Informed by laboratory and field measurements from a tropical forest, our results suggest that soil moisture and litterfall rates are the primary drivers of iron fluctuations at daily-to-seasonal temporal scales. We also emphasize the important role of soil iron cycle in the decomposition of the organic matter.

International audience; The NUMEN experimental activity with accelerated beams is performed at INFN–Laboratori Nazionali del Sud (LNS) in Catania using the Superconducting Cyclotron and the MAGNEX magnetic spectrometer. The scientific motivation of NUMEN is to extract experiment-driven information on the nuclear matrix elements entering in the expression of the 0νββ decay half-life. The reaction cross sections involved, especially for the double charge exchange process, are very low, thus limiting the present exploration to a few selected isotopes of interest in the context of typically low-yield experimental runs. In order to make feasible a systematic study of all the candidate nuclei, a major upgrade of the LNS facility is foreseen to increase the experimental yield by more than two orders of magnitude. To this purpose, frontier technologies are being developed for the accelerator and the detection systems. An updated description of the choices derived from the recent R&D activity on the target system and MAGNEX focal plane detector is given.

Enhanced weathering (EW) scenarios are analyzed using the model presented in Cipolla et al. (2020). We explore the role of different hydroclimatic forcing on carbon-sequestration efficiencies. We also investigate whether increasing soil carbon content improves weathering conditions. We link olivine weathering rates to pH variations and quantify the suitability of hydroclimatic regimes to EW, based on rainfall intensity and frequency. The results show that the amount of CO 2 reacting with olivine and ending up in solution in the form of HCO 3 − and CO 3 2 − increases with mean annual precipitation (MAP) up to 2000 mm, but then tapers off for higher MAPs. On the contrary, the sequestered CO 2 continues to grow with MAP in a more significant way. We also quantify the increase of nutrients availability, especially when MAP exceeds 2000 mm. Lastly, the results suggest that organic matter amendments are more effective in humid environments (MAP higher than 2000 mm), confirming the central role of hydrologic processes on EW.

The40Ca(18O,18F)40K single charge exchange (SCE) reaction is explored at an incident energy of 275 MeV and analyzed consistently by collecting the elastic scattering and inelastic scattering data under the same experimental conditions. Full quantum-mechanical SCE calculations of the direct mechanism are performed by including microscopic nuclear structure inputs and adopting either a bare optical potential or a coupled channel equivalent polarization potential (CCEP) constrained by the elastic and inelastic data. The direct SCE mechanism describes the magnitude and shape of the angular distributions rather well, thus suggesting the suppression of sequential multi-nucleon transfer processes.

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. The main experimental tools for this project are the K800 Superconducting Cyclotron and MAGNEX spectrometer at the INFN-LNS laboratory. However, the tiny values of DCE cross-sections and the resolution requirements demand beam intensities much higher than those manageable with the present facility. The on-going upgrade of the INFN-LNS facilities promoted by the POTLNS a project in this perspective is intimately connected to the NUMEN project. This paper describes the solutions proposed as a result of the R&D activity performed during the recent years. The goal is to develop suitable technologies allowing for the measurements of DCE cross-section under extremely high beam intensities. a PIR01_00005 — potenziamento dell’infrastruttura di ricerca Laboratori Nazionali del Sud per la produzione di fasci di ioni ad alta intensitá.

The 4He(4He,4He)4He* inelastic scattering was revisited in a new coincidence measurement at the MAGNEX facility of Istituto Nazionale di Fisica Nucleare – Laboratori Nazionali del Sud. The 4He + 4He → 4He + 4He* → 4He + 3H + 1H and 4He + 4He → 4He + 4He* → 4He + 3He + n reactions were measured simultaneously by detecting the 4He particles at the MAGNEX magnetic spectrometer in coincidence with the 3H and 3He at the OSCAR silicon telescope. The main concept of the experiment is described and the data reduction strategy is reported.

The 18O+48Ti reaction was studied at the energy of 275 MeV for the first time under the NUMEN and NURE experimental campaigns with the aim to investigate the complete net of reaction channels potentially involved in the 48Ca→48Ti double charge exchange transition. Such a transition is of great interest because of its relevance to the extraction of 48Ca→48Ti double beta decay nuclear matrix element. The relevant experiment was carried out at the MAGNEX facility of INFN-LNS in Catania. Angular distribution measurements for the various reaction products were performed by using the MAGNEX large acceptance magnetic spectrometer. The present contribution is focused on the analysis of the one-proton transfer channel with emphasis on the particle identification technique and the estimation of background contaminations.

Double 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.

Background: In our recent experiment, $^9$Be+p at 5.67A MeV, the breakup decay rates to the 3 configurations, $\alpha$+$\alpha$+n, $^8$Be$^*$+n and $^5$He+$^4$He of $^9$Be, were observed and quantified, in a full kinematics approach. Unfolding step by step the accessibility to the above configurations, it will require similar studies at lower and higher energies as well as the interpretation of the data in a theoretical framework. Purpose: Investigate the breakup decay rate of $^9$Be+p at 2.72A MeV, where the $\alpha$+$\alpha$+n configuration is mainly accessible. Compare and interpret data at 2.72A MeV and 5.67A MeV into a 4-body CDCC formalism; Point out and discuss couplings to continuum. Methods: Our experimental method includes an exclusive breakup measurement in a full kinematic approach of $^9$Be incident on a proton target at 2.72A MeV, together with elastic scattering and other reaction channels measurements under the same experimental conditions. The interpretation of the data at 2.72A MeV and 5.67A MeV is considered in a 4-body CDCC approach, using the Transformed Harmonic Oscillator method for the 3-body projectile. Results: An elastic scattering angular distribution at 2.72A MeV is measured, which compares very well with CDCC calculations, indicating a strong coupling to continuum. At the same energy, the measured breakup and total reaction cross sections present good agreement with the calculated values. Further on, the elastic scattering and breakup cross section data at 5.67A MeV are found in very good agreement with the CDCC calculations. The present results support further our 3-body model for the structure of $^9$Be, validating relevant radiative reaction rates obtained previously.

Background: Heavy-ion induced two-nucleon transfer reactions are powerful tools to reveal peculiar aspects of the atomic nucleus, such as pairing correlations, single-particle and collective degrees of freedom, and more. Also, these processes are in competition with the direct meson exchange in the double charge exchange reactions, which have recently attracted great interest due to their possible connection to neutrinoless double-beta decay. In this framework, the exploration of two-nucleon transfer reactions in the 20Ne+116Cd collision at energies above the Coulomb barrier is particularly relevant since the 116Cd nucleus is a candidate for the double-beta decay. Methods: We measured the excitation energy spectra and absolute cross sections for the two reactions using the MAGNEX large acceptance magnetic spectrometer to detect the ejectiles. We performed direct coupled reaction channels and sequential distorted wave Born approximation calculations using the double folding S\~ao Paulo potential to model the initial and final state interactions. The spectroscopic amplitudes for two- and singleparticle transitions were derived by different nuclear structure approaches: microscopic large-scale shell model, interacting boson model-2 and quasiparticle random phase approximation. Results: The calculations are able to reproduce the experimental cross sections for both two-neutron and twoproton transfer reactions. The role of couplings with the inelastic channels are found to be important in the two-proton transfer case. A competition between the direct and the sequential process is found in the reaction mechanism. For the two-proton transfer case, the inclusion of the 1g7/2 and 2d5/2 orbitals in the model space is crucial.

The breakup of 9Be is studied via an inelastic scattering experiment on a proton target at 5.6 A MeV in inverse kinematics. Two of the three cluster constituents (α and α) as well as the proton target recoil were recorded in a triple coincidence mode allowing a full kinematics approach analysis. In this respect relative α - α and α - n, Q-value and 9Be excitation spectra, energy spectra for all fragments as well as the energy spectrum of the recoil proton were reconstructed. A clear signature of the two breakup sequential modes (5He + 4He and 8Be + n) was identified via the recoiling proton reconstructed spectra together with the direct breakup decay. A strong 5He + 4He mode was observed compatible with previous beta decay experiments.

Physics cases of increasing interest in the recent years, such as the study of double charge exchange reactions for neutrino physics, require the study of very suppressed reaction channels in medium-heavy ion induced nuclear reactions. The main experimental challenges are the possibility to identify and detect the medium-heavy quasi-projectiles and the capability to measure very low cross-sections (few nb) with high sensitivity at very forward angles, including zero degree. The experimental techniques adopted in the setup of the MAGNEX magnetic spectrometer to face these issues are described in this paper., arXiv admin note: substantial text overlap with arXiv:1811.08693

In the predominantly oxic, upland soils, periods of high wetness trigger anaerobic processes such as iron (Fe) reduction within the soil microsites, with implications for organic matter decompositi...

Chemical weathering is one of the major processes interacting with climate and tectonics to form clays, supply nutrients to soil micro-organisms and plants, and sequester atmospheric CO2. Hydrology and dissolution kinetics have been emphasized as factors controlling chemical weathering rates. However, the interaction between hydrology and transport of dissolved inorganic carbon (DIC) in controlling weathering has received less attention. In this paper, we present an analytical model that couples subsurface water and chemical molar balance equations to analyze the roles of hydrology and DIC-transport on chemical weathering. The balance equations form a dynamical system that fully determines the dynamics of the weathering zone chemistry as forced by the transport of DIC. The model is formulated specifically for the silicate mineral albite, but it can be extended to other minerals, and is studied as a function of percolation rate and water transit time. Three weathering regimes are elucidated. For very small or large values of transit time, the weathering is limited by reaction kinetics or transport, respectively. For intermediate values, the system is transport-controlled and is sensitive to transit time. We apply the model to a series of watersheds for which we estimate transit times and identify the type of weathering regime. The results suggest that hydrologic transport of DIC may be as important as reaction kinetics and dilution in determining chemical weathering rates.