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Studies of charged-particle reactions for low-energy nuclear astrophysics require high sensitivity, which can be achieved by means of detection setups with high efficiency and low backgrounds, to obtain precise measurements in the energy region of interest for stellar scenarios. High-efficiency total absorption spectroscopy is an established and powerful tool for studying radiative capture reactions, particularly if combined with the cosmic background reduction by several orders of magnitude obtained at the Laboratory for Underground Nuclear Astrophysics (LUNA). We present recent improvements in the detection setup with the Bismuth Germanium Oxide (BGO) detector at LUNA, aiming to reduce high-energy backgrounds and increase the summing detection efficiency. The new design results in enhanced sensitivity of the BGO setup, as we demonstrate and discuss in the context of the first direct measurement of the 65 keV resonance (E x = 5672 keV) of the 17O(p,γ)18F reaction. Moreover, we show two applications of the BGO detector, which exploit its segmentation. In the case of complex γ-ray cascades, e.g. the de-excitation of E x = 5672 keV in 18F, the BGO segmentation allows to identify and suppress the beam-induced background signals that mimic the sum peak of interest. We demonstrate another new application for such a detector in form of in situ activation measurements of a reaction with β + unstable product nuclei, e.g. the 14N(p,γ)15O reaction.

In 2012, Italy was struck by a seismic crisis characterized by two main shocks (ML 5.9 and 5.8) and relevant liquefaction events. Terre del Reno (Emilia-Romagna Region) is one of the municipalities that experienced the most extensive liquefaction effects due to its complex geo-stratigraphic and geo-morphological setting. Thus, it was chosen as case study for the PERL project, devoted to defining a new integrated methodology to assess the liquefaction susceptibility in complex stratigraphic conditions through a multi-level approach. About 1800 geotechnical, geophysical and hydrogeological investigations were collected and stored in a publicly available dataset named PERL that is here presented.

Background: The competing Ne22(α,γ)Mg26 and Ne22(α,n)Mg25 reactions control the production of neutrons for the weak s process in massive and asymptotic giant branch (AGB) stars. In both systems, the ratio between the corresponding reaction rates strongly impacts the total neutron budget and strongly influences the final nucleosynthesis. A number of experimental studies have been performed over recent years which necessitate the reevaluation of the Ne22(α,γ)Mg26 and Ne22(α,n)Mg25 reaction rates. Evaluations of the reaction rates following the collection of new nuclear data presently show differences of up to a factor of 500, resulting in considerable uncertainty in the resulting nucleosynthesis. Purpose: To reevaluate the Ne22(α,γ)Mg26 and Ne22(α,n)Mg25 reaction rates using updated nuclear data from a number of sources including updating spin and parity assignments. Methods: With updated spin and parity assignments, the levels which can contribute to the reaction rates are identified. The reaction rates are computed using a Monte Carlo method which has been used for previous evaluations of the reaction rates in order to focus solely on the changes due to modified nuclear data. Results: The evaluated Ne22(α,γ)Mg26 reaction rate remains substantially similar to that of Longland et al. but, including recent results from Texas A&M, the Ne22(α,n)Mg25 reaction rate is lower at a range of astrophysically important temperatures. Stellar models computed with newton and mesa predict decreased production of the weak branch s process due to the decreased efficiency of Ne22 as a neutron source. Using the new reaction rates in the mesa model results in Zr96/Zr94 and Ba135/Ba136 ratios in much better agreement with the measured ratios from presolar SiC grains. Conclusion: The Ne22+α reaction rates Ne22(α,γ)Mg26 and Ne22(α.n)Mg25 have been recalculated based on more recent nuclear data. The Ne22(α,γ)Mg26 reaction rate remains substantially unchanged since the previous evaluation but the Ne22(α.n)Mg25 reaction rate is substantially decreased due to updated nuclear data. This results in significant changes to the nucleosynthesis in the weak branch of the s process.

In patients with severe aortic stenosis, the presence of left ventricular systolic dysfunction is one of the main predictors of adverse events after valve replacement surgery. However, more and more patients are being referred for surgery early and have preserved systolic function at the time of surgery. Within this category, global longitudinal strain (GLS) has been proposed as a marker of ventricular remodeling after cardiac surgery. Our study aims to identify the variation of Global longitudinal strain (GLS) in patients undergoing aortic valve replacement and any differences compared to classes of diastolic dysfunction. Methods From June 2020 to June 2022 we analyzed patients with severe aortic stenosis with an indication for cardiac surgery treatment admitted to the cardiac surgery department of our AOU. All patients underwent an echocardiogram immediately before surgery and in the early postoperative period (mean 7 days). In all cases, the GLS of the left ventricle was calculated and patients were divided into four classes according to the degree of diastolic dysfunction (0–III) according to the most recent international guidelines. The data were analyzed with SPSS 28 software. Analysis of variance was performed with a t–test and ANOVA test. Results In the final analysis, 63 patients were included, with a mean age of 70.5±8.2%, of whom 28 were women (44.4%) and 35 were men (55.6%). In 12 patients (19%) ischaemic heart disease with an indication for coronary revascularization was also present. The mean preoperative ejection fraction was 59±9.5%. The mean GLS values before surgery were 15.26±4.3% vs. early postoperative 12.52±2.6%, p Conclusions In our case series, patients with severe aortic stenosis undergoing aortic valve replacement with or without myocardial revascularization show a significant early reduction in GLS regardless of the degree of diastolic dysfunction. An extension of follow–up is needed to assess any differences in the intervention‘s benefit in different diastolic dysfunction subgroups.

The 18O(p,α)15N reaction affects the synthesis of 15N, 18O and 19F isotopes, whose abundances can be used to probe the nucleosynthesis and mixing processes occurring deep inside asymptotic giant branch (AGB) stars. We performed a low-background direct measurement of the 18O(p,α)15N reaction cross-section at the Laboratory for Underground Nuclear Astrophysics (LUNA) from center of mass energy Ec.m.=340 keV down to Ec.m.=55 keV, the lowest energy measured to date corresponding to a cross-section of less than 1 picobarn/sr. The strength of a key resonance at center of mass energy Er=90 keV was found to be a factor of 10 higher than previously reported. A multi-channel R-matrix analysis of our and other data available in the literature was performed. Over a wide temperature range, T=0.01–1.00 GK, our new astrophysical rate is both more accurate and precise than recent evaluations. Stronger constraints can now be placed on the physical processes controlling nucleosynthesis in AGB stars with interesting consequences on the abundance of 18O in these stars and in stardust grains, specifically on the production sites of oxygen-rich Group II grains., SCOPUS: ar.j, info:eu-repo/semantics/published

Terre del Reno is a municipality in the Emilia-Romagna Region (Italy) that experienced relevant liquefaction events during the 2012 seismic crisis, which was characterised by two main shocks (ML 5.9 and 5.8). Such events are mainly related to the complex geo-stratigraphic setting of the area. In this background, the present work is devoted to achieving two main objectives: i) define a new integrated methodology to assess liquefaction susceptibility in complex stratigraphic conditions through a multi-level approach; ii) perform a level 3 seismic microzonation study of Terre del Reno. To this purpose, more than one thousand geophysical and geotechnical measurements available from three different databases and some hundreds of new collected investigations were stored in a dedicated geodatabase. Data and metadata, that were spatially and statistically manipulated to guarantee their harmonization, standardization, and uniqueness, were explored to reconstruct a model for the Terre del Reno subsoil. Specifically, a geological model of the studied area (~ several hundreds of meters) was first reconstructed as well as the seismic bedrock geometry (the latter defines as the layer characterized by the stiffness requirement: Vs > 800 m/s). This model was obtained by integrating deep bore-hole data available from previous studies and geophysical and geotechnical investigations. Furthermore, a high-resolution geological reconstruction of the upper 30 m has also been performed through sedimentological and paleo morphological analysis to characterize the sedimentary units affected by liquefaction. This analysis may be used to compare both well-known and innovative geotechnical indicators for liquefaction susceptibility assessment. Thus, a set of acceleration time histories, that are spectrum-compatibles with the spectrum of reference input motion at outcropping bedrock of the site, were used as input in 1D and 2D site effect numerical modelling. The obtained results were synthetized and represented in a level 3 seismic microzonation study with the aim of providing operational indicators devoted to urban planning and for challenging problem related to liquefaction.

The huge impact caused by liquefaction during past earthquakes stimulates the interest of researchers in investigating the factors ruling the susceptibility of subsoil and the triggering conditions. The concern of stakeholders raises the need for risk assessment methods applicable at the large scale. A crucial aspect for liquefaction risk assessment consists in the subsoil characterization, with the stratigraphic classification into homogeneous soil layers and the identification of the susceptible volumes, with the aim of constructing 2D and 3D geo-mechanical models. In the current practice, the CPT-based soil behavior type (SBT) and the soil behavior type index (Ic), are widely used to identify soil boundaries discontinuities (Robertson, 2016). Sometimes, the interpretation of subsoil profile is not immediate and unique, due to the lack of evident boundary changes. In these cases, the need is felt for sound, widely applicable tools that provide univocal identification of subsoil strata. Statistical procedure, developed over the years, provides a less subjective interpretation of the subsoil and, in conjunction with artificial intelligence, can lead to improve the current methodology obtaining an objective and extensive site characterization. This work exposes a data-driven analysis for the subsoil stratigraphic recognition combining geostatistical tools and AI genetic algorithms. The presented procedure is calibrated and validated on the case study of Terre del Reno (Italy), severely struck by liquefaction during the 2012 Mw 6.1 earthquake and characterized by complex geo-stratigraphic conditions. The selected area, homogeneously covered by about 1700 geognostic surveys, is investigated within the "PERL" research project, carried out by the Emilia Romagna Region (RER), CNR-IGAG and UniCas-DiCeM, aiming to provide a reliable procedure for liquefaction risk assessment and a seismic microzonation. From the RER geodatabase, 102 pairs of complementary CPT and boreholes were extracted to calibrate the method, defined as the couples of surveys located at a relative distance less than 30m, considered for this purpose as spatially correlated. Starting from the information available from the boreholes, a geologic-sedimentologic study has been carried out to define the main stratigraphic units. In parallel, CPT profiles are processed with a statistical method based on the spatial variability analysis of the measured parameters, identifying statistically homogeneous layers and associating to each of them the correspondent stratigraphic unit reported in the complementary borehole. At this stage, an artificial intelligence algorithm has been calibrated merging the outcomes derived from couples of CPTs and boreholes. Subsequently, the procedure has been applied to the remaining CPTs, combining the geological and geotechnical knowledge of the subsoil in an efficient and automatic way to enable a large-scale reconstruction of the subsoil stratigraphy.

In this paper, we report a detailed study on the de-excitation of the 46Ti compound nucleus populated by means of four different reactions: 16O + 30Si at 7 and 8 AMeV, 18O + 28Si at 7 AMeV and 19F + 27Al at 7 AMeV. The GARFIELD detection array was used to measure the light charged particles and the heavy fragments emitted. This setup covers a large fraction of the solid angle with high-granularity. Complete events are chosen through total charge (Z TOT = 22) detection. Fusion-evaporation events are selected based on the condition that only one heavy fragment is detected in coincidence with the light charged particles. The analysis of global observables, such as charge distribution and light charged particle multiplicities, is compatible with the formation of a thermalized compound nucleus for all the four reactions. Nevertheless, an enhanced emission of α-particles with respect to a pure statistical picture is observed at very forward angles (α-particles.

One of the main neutron sources for the astrophysical s process is the reaction ^{13}C(α,n)^{16}O, taking place in thermally pulsing asymptotic giant branch stars at temperatures around 90 MK. To model the nucleosynthesis during this process the reaction cross section needs to be known in the 150-230 keV energy window (Gamow peak). At these sub-Coulomb energies, cross section direct measurements are severely affected by the low event rate, making us rely on input from indirect methods and extrapolations from higher-energy direct data. This leads to an uncertainty in the cross section at the relevant energies too high to reliably constrain the nuclear physics input to s-process calculations. We present the results from a new deep-underground measurement of ^{13}C(α,n)^{16}O, covering the energy range 230-300 keV, with drastically reduced uncertainties over previous measurements and for the first time providing data directly inside the s-process Gamow peak. Selected stellar models have been computed to estimate the impact of our revised reaction rate. For stars of nearly solar composition, we find sizeable variations of some isotopes, whose production is influenced by the activation of close-by branching points that are sensitive to the neutron density, in particular, the two radioactive nuclei ^{60}Fe and ^{205}Pb, as well as ^{152}Gd.

One of the main neutron sources for the astrophysical s process is the reaction ^{13}C(α,n)^{16}O, taking place in thermally pulsing asymptotic giant branch stars at temperatures around 90 MK. To model the nucleosynthesis during this process the reaction cross section needs to be known in the 150-230 keV energy window (Gamow peak). At these sub-Coulomb energies, cross section direct measurements are severely affected by the low event rate, making us rely on input from indirect methods and extrapolations from higher-energy direct data. This leads to an uncertainty in the cross section at the relevant energies too high to reliably constrain the nuclear physics input to s-process calculations. We present the results from a new deep-underground measurement of ^{13}C(α,n)^{16}O, covering the energy range 230-300 keV, with drastically reduced uncertainties over previous measurements and for the first time providing data directly inside the s-process Gamow peak. Selected stellar models have been computed to estimate the impact of our revised reaction rate. For stars of nearly solar composition, we find sizeable variations of some isotopes, whose production is influenced by the activation of close-by branching points that are sensitive to the neutron density, in particular, the two radioactive nuclei ^{60}Fe and ^{205}Pb, as well as ^{152}Gd.

Light elements were produced in the first few minutes of the Universe through a sequence of nuclear reactions known as Big Bang nucleosynthesis (BBN)1,2. Among the light elements produced during BBN1,2, deuterium is an excellent indicator of cosmological parameters because its abundance is highly sensitive to the primordial baryon density and also depends on the number of neutrino species permeating the early Universe. Although astronomical observations of primordial deuterium abundance have reached percent accuracy3, theoretical predictions4,5,6 based on BBN are hampered by large uncertainties on the cross-section of the deuterium burning D(p,γ)3He reaction. Here we show that our improved cross-sections of this reaction lead to BBN estimates of the baryon density at the 1.6 percent level, in excellent agreement with a recent analysis of the cosmic microwave background7. Improved cross-section data were obtained by exploiting the negligible cosmic-ray background deep underground at the Laboratory for Underground Nuclear Astrophysics (LUNA) of the Laboratori Nazionali del Gran Sasso (Italy)8,9. We bombarded a high-purity deuterium gas target10 with an intense proton beam from the LUNA 400-kilovolt accelerator11 and detected the γ-rays from the nuclear reaction under study with a high-purity germanium detector. Our experimental results settle the most uncertain nuclear physics input to BBN calculations and substantially improve the reliability of using primordial abundances to probe the physics of the early Universe.

The astrophysical Li6(p,γ)Be7 reaction occurs during Big Bang nucleosynthesis and the pre-main sequence and main sequence phases of stellar evolution. The low-energy trend of its cross section remains uncertain, since different measurements have provided conflicting results. A recent experiment reported a resonancelike structure at center-of-mass energy 195 keV, associated to a positive-parity state of Be7. The existence of such resonance is still a matter of debate. We report a new measurement of the Li6(p,γ)Be7 cross section performed at the Laboratory for Underground Nuclear Astrophysics, covering the center-of-mass energy range E=60-350 keV. Our results rule out the existence of low-energy resonances. The astrophysical S-factor varies smoothly with energy, in agreement with theoretical models.

Background: Shell hydrogen burning during the asymptotic giant branch (AGB) phase through the oxygen isotopes has been indicated as a key process that is needed to understand the observed O 18 / O 16 relative abundance in presolar grains and in stellar atmospheres. This ratio is strongly influenced by the relative strengths of the reactions O 18 ( p , α ) N 15 and O 18 ( p , γ ) F 19 in low-mass AGB stars. While the former channel has been the focus of a large number of measurements, the ( p , γ ) reaction path has only recently received some attention and its stellar reaction rate over a wide temperature range rests on only one measurement. Purpose: Our aim is the direct measurement of states in F 19 as populated through the reaction O 18 ( p , γ ) F 19 to better determine their influence on the astrophysical reaction rate, and more generally to improve the understanding of the nuclear structure of F 19 .Method: Branchings and resonance strengths were measured in the proton energy range E p lab = 150 – 400 keV , using a high-purity germanium detector inside a massive lead shield. The measurement took place in the ultra-low-background environment of the Laboratory for Underground Nuclear Astrophysics (LUNA) experiment at the Gran Sasso National Laboratory, leading to a highly increased sensitivity. Results: The uncertainty of the γ branchings and strengths was improved for all four resonances in the studied energy range; many new transitions were observed in the case of the 334 keV resonance, and individual γ decays of the 215 keV resonance were measured for the first time. In addition a number of transitions to intermediate states that decay through α emission were identified. The strengths of the observed resonances are generally in agreement with literature values. Conclusions: Our measurements substantially confirm previous determinations of the relevant resonance strengths. Therefore the O 18 ( p , γ ) F 19 reaction rate does not change with respect to the reaction rate reported in the compilations commonly adopted in the extant computations of red-giant branch and AGB stellar models. Nevertheless, our measurements definitely exclude a nonstandard scenario for the fluorine nucleosynthesis and a nuclear physics solution for the O 18 depletion observed in Group 2 oxygen-rich stardust grains.