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We introduce the LUNA neutron detector array developed for the investigation of the 13C(α, n)16O reaction towards its astrophysical s-process Gamow peak in the low-background environment of the Laboratori Nazionali del Gran Sasso (LNGS). Eighteen 3He counters are arranged in two different configurations (in a vertical and a horizontal orientation) to optimize neutron detection efficiency, target handling and target cooling over the investigated energy range Eα,lab=300−400 keV (En=2.2−2.6MeV in emitted neutron energy). As a result of the deep underground location, the passive shielding of the setup and active background suppression using pulse shape discrimination, we reached a total background rate of 1.23±0.12 counts/hour. This resulted in an improvement of two orders of magnitude over the state of the art allowing a direct measurement of the 13C(α, n)16O cross-section down to Eα,lab=300 keV. The absolute neutron detection efficiency of the setup was determined using the 51V(p,n)51Cr reaction and an AmBe radioactive source, and completed with a Geant4 simulation. We determined a (34 ± 3)% and (38 ± 3)% detection efficiency for the vertical and horizontal configurations, respectively, for En=2.4MeV neutrons.

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 13C({\alpha},n)16O, 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 150-230keV 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 13C({\alpha},n)16O, covering the energy range 230-300keV, 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 60Fe and 205Pb, as well as 152Gd, Comment: 7 pages, 4 figures, accepted on PRL on 17th August 2021

In the frame of an integrated knowledge path applied to the archaeological site of Hierapolis in Phrygia (Turkey), several mortar samples were collected and analysed by means of a multi-analytical approach to study the production techniques and the conservation state, and to evaluate the possible dateability by means of the absolute radiocarbon dating method (14C). This study was part of a collaboration research including structural engineering and geophysical investigations, aimed at evaluating the current conditions of the archaeological remains for the possible use of the whole site as an archaeo-seismic park.

Direct measurements of reaction cross-sections at astrophysical energies often require the use of solid targets able to withstand high ion beam currents for extended periods of time. Thus, monitoring target thickness, isotopic composition, and target stoichiometry during data taking is critical to accountfor possible target modifications and to reduce uncertainties in the final cross-section results. A common technique used for these purposes is the Nuclear Resonant Reaction Analysis (NRRA), which however requires that a narrow resonance be available inside the dynamic range of the accelerator used. In caseswhen this is not possible, as for example the 13C(α,n)16O reaction recently studied at low energies at the Laboratory for Underground Nuclear Astrophysics (LUNA) in Italy, alternative approaches must be found. Here, we present a new application of the shape analysis of primary ϒ rays emitted by the 13C(p,)14Nradiative capture reaction. This approach was used to monitor 13C target degradation in situ during the13C(α,n)16O data taking campaign. The results obtained are in agreement with evaluations subsequently performed at Atomki (Hungary) using the NRRA method. A preliminary application for the extraction ofthe 13C(α,n)16O reaction cross-section at one beam energy is also reported.

One of the main neutron sources for the astrophysical s process is the reaction C 13 (α ,n )O 16 , 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 C 13 (α ,n )O 16 , 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 Fe 60 and Pb 205 , as well as Gd 152 .

One of the main neutron sources for the astrophysical s-process is the reaction 13C(��,n)16O, 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 150-230keV 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 13C(��,n)16O, covering the energy range 230-300keV, 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 60Fe and 205Pb, as well as 152Gd, 7 pages, 4 figures, accepted on PRL on 17th August 2021

We introduce the LUNA neutron detector array developed for the investigation of the 13C(𝛼, 𝑛)16O reaction towards its astrophysical 𝑠-process Gamow peak in the low-background environment of the Laboratori Nazionali del Gran Sasso (LNGS). Eighteen 3He counters are arranged in two different configurations (in a vertical and a horizontal orientation) to optimize neutron detection efficiency, target handling and target cooling over the investigated energy range E𝛼,lab = 300 − 400 keV (En = 2.2 − 2.6 MeV in emitted neutron energy). As a result of the deep underground location, the passive shielding of the setup and active background suppression using pulse shape discrimination, we reached a total background rate of 1.23 ± 0.12 counts/hour. This resulted in an improvement of two orders of magnitude over the state of the art allowing a direct measurement of the 13C(𝛼, 𝑛)16O cross-section down to E𝛼,lab = 300 keV. The absolute neutron detection efficiency of the setup was determined using the 51V(p,n)51Cr reaction and an AmBe radioactive source, and completed with a Geant4 simulation. We determined a (34 ± 3)% and (38 ± 3)% detection efficiency for the vertical and horizontal configurations, respectively, for En = 2.4 MeV neutrons.

Radiocarbon dating was used on mortars exploiting the C uptake during the carbonation process, where the atmospheric CO2 signal is absorbed by reaction with lime putty, and then it is converted back into CaCO3-binder containing the signature of the construction time. The CaCO3-binder must be isolated from other carbonate sources and contaminants such as delayed hydraulic and secondary alteration products which could affect the dating process [1]–[3]. An appropriate mineralogical characterization of the mortar greatly enhances the understanding of the reaction history of the material allowing the preliminary assessment of the “dateability” of the binder, and afterwards, the choice of the needed pretreatments for a reliable radiocarbon dating. In this paper, our procedures in mortar characterization, binder isolation and innovative treatments of the fine binder fraction in order to obtain a suitable dateable material are shown.

CIRCE (Università della Campania “Luigi Vanvitelli”) and CIRCe (Università di Padova) represent a unique multidisciplinary group with competences spanning different fields of research, from applied physics to geology, and including geochemistry involved in the development and characterization of dating methodologies for anthropogenic carbonates and mortars. Mortar dating often requires a specific tuninig of the applied procedure driven by the characteristics of each specimen in order to guarantee accurate dating. Such tuning is driven by the complex characteristics of mortars, and is often inferred by means of analyses such as Optical Microscopy on Thin Sections (TSOM), X-Ray Diffractometry (XRD) and Scanning Electron Microscopy Energy Dispersion X-ray Spectroscopy (SEM-EDS), but ultimately rely on the measurement of radiocarbon isotope ratios. Aiming to decrease the economic effort spent on dating the development of pre-screening analyses geared towards mortar quality evaluations represents a desirable tool. In this paper a model describ-ing the relationship between measured mortar δ13C and observed offset in radiocarbon ages is developed and validated onto a previ-ously published dataset Marzaioli et al. 2011a. Overall agreement verified on this experimental dataset allowed us to simulate δ13C for archeological mortars, pointing out its validity in a defined range, especially if measured using the purification procedure.

The review of an old14C dating investigation and the new radi-ometric analysis on 10 different samples, conducted by the Center for Isotopic Research on Cultural and Environmental heritage (CIRCE) of the University of Campania “Luigi Vanvitelli”, through the AMS (Accelerator Mass Spectrometry), offer useful elements to date the excavation and relative phases of the catacomb of St. Ianuarius, the most important Late Antique cemetery in Naples. Several excavations have been carried out in the catacomb since the nineteenth century, not always conducted in a systematic manner and published only in part. In the last decade, the Pontifical Commission for Sacred Archeology has started the edition of the old excavations and finds, thanks also to the archaeometric analysis. The recalibration of a previous measurement of a beam fragment discovered during the excavations carried out in the 1970s, based on the new IntCal 13 Calibration Curve and the Oxcal Software 4.3, allowed the finding to be more correctly dated to 530-659 A.D. (±2σ). The AMS reduces not only the14C isotopic measurement time but also the weight of the material used for dating. Furthermore, advances in chemical treatments on samples of different nature make it possible not only to quantify radiocarbon in a wider range of organic materials but also, through an innovative calcite extraction process, dating from mortars (first mortar radiocarbon dating of the catacombs analyzed). The results obtained in this study expand our knowledge on the catacomb not only in Late Antiquity and in the Middle Ages, but also in the following centuries (see the dating of the samples Sgn 1, Sgn 2, Sgn 3, Sgn 6).

Direct measurements of reaction cross-sections at astrophysical energies often require the use of solid targets able to withstand high ion beam currents for extended periods of time. Thus, monitoring target thickness, isotopic composition, and target stoichiometry during data taking is critical to account for possible target modifications and to reduce uncertainties in the final cross-section results. A common technique used for these purposes is the Nuclear Resonant Reaction Analysis (NRRA), which however requires that a narrow resonance be available inside the dynamic range of the accelerator used. In cases when this is not possible, as for example the 13C(alpha,n)16O reaction recently studied at low energies at the Laboratory for Underground Nuclear Astrophysics (LUNA) in Italy, alternative approaches must be found. Here, we present a new application of the shape analysis of primary gamma rays emitted by the 13C(p,g)14N radiative capture reaction. This approach was used to monitor 13C target degradation {\em in situ} during the 13C(alpha,n)16O data taking campaign. The results obtained are in agreement with evaluations subsequently performed at Atomki (Hungary) using the NRRA method. A preliminary application for the extraction of the 13C(alpha,n)16O reaction cross-section at one beam energy is also reported., Comment: 10 pages, 6 figures, to be published in EPJ A

The stable isotope composition of living and of Holocene Mytilidae shells was measured in the area of Camarones (Chubut, Argentina). The most striking results were the high &delta, 18O values measured in samples older than ca. 6.1 cal ka BP. In the younger samples, the &delta, 18O values remained substantially stable and similar to those of living specimens. Analysis of the data revealed the possibility for this isotopic shift to be driven mainly by changes in temperature probably accompanied by minor changes in salinity, suggesting cooler seawater before 6.1 cal ka BP, with a maximum possible temperature shift of ca. 5 &deg, C. A possible explanation of this change can be related to a northward position of the confluence zone of the Falkland and Brazilian currents. This is consistent with the data obtained in marine cores, which indicate a northerly position of the confluence in the first half of the Holocene. Our data are also in line with the changes in wind strength and position of the Southern Westerlies Wind, as reconstructed in terrestrial proxies from the Southernmost Patagonia region.

Annually resolved radiocarbon (¹⁴C) measurements on tree rings led to the discovery of abrupt variations in ¹⁴C production attributed to large solar flares. We present new results of annual and subannual ¹⁴C fluctuations in tree rings from a middle-latitude sequoia (California) and a high-latitude pine (Finland), analyzed for the period 1030–1080 CE, to trace a possible impact of the Crab supernova explosion, occurring during the Oort minimum of solar activity. Our results indicate an increase of Δ¹⁴C around 1054/55 CE, which we estimate is higher in magnitude than the cyclic variability due to solar activity at a 2σ significance level. The net signal appears to be synchronized in the studied locations. Several sources of this event are possible including γ-rays from the Crab supernova, an unusually weak solar minimum or a solar energetic particle incident. More data are needed to provide more insight into the origin of this ¹⁴C event.

This work derives from the requirement to investigate on the silver surface enrichment of objects of historical and artistic interest using the X-ray fluorescence non-destructive technique (XRF). The aim is the thickness estimation through the experimental relationship between K K α β and K Lα α of Ag as a function of the thickness. Measurements on silver sheets of different thicknesses and three concentrations are carried out using a XRF spectrometer with a maximum voltage of 50 kV. The results allow to analyse the plating layer of silver objects also to make other interesting considerations. © 2018 Societa Italiana di Fisica. All rights reserved.

7Be(p,γ)8B has an important role in nuclear astrophysics, having a direct impact on both the high energy component of solar neutrinos and the 7Li abundance after the Big Bang Nucleosynthesis. All direct measurements providing useful information on this reaction so far used the same approach, i.e. a proton beam on a radioactive 7Be target. The overall precision and accuracy of the estimate of the astrophysical rate of this reaction are limited by the discrepancy between the results of existing measurements, possibly due to the complicated stoichiometry and beam induced deterioration of the radioactive targets. The ERNA (European Recoil separator for Nuclear Astrophysics) collaboration planned a new experiment in inverse kinematics exploiting the intense 7Be beam available at CIRCE (Center for Isotopic Research on Cultural and Environmental heritage), Caserta, Italy. The 8B recoils are produced in a windowless hydrogen gas target and detected after the efficient mass separation provided by ERNA. Here we present the commissioning of the experimental setup and a first cross section measurement at Ecm≈ 812 keV.

The fusion reaction C12(C12,p)Na23 has been studied from E=2.00 to 4.00 MeV by particle spectroscopy. The data reveal broad resonances above E=3.00 MeV and are compatible with previously reported resonance structure around E=2.1 MeV. The data were limited at low energies by low count rates as well as possible background contributions. This experiment extends the previously achieved low-energy measurement by charged particle spectroscopy to 2 MeV, which corresponds to the high-energy side of the astrophysically relevant temperature. Present knowledge of level structures and nonresonant contribution cannot explain the results of the present experiment, which may change the C12+C12 reaction rate significantly. Despite the progress decreasing the low-energy limit, any extrapolation into the astrophysical energy range remains highly uncertain based on available experimental data.

The fusion reaction C-12 (C-12 ,p)Na-23 has been studied from E = 2.00 to 4.00 MeV by particle spectroscopy. The data reveal broad resonances above E = 3.00 MeV and are compatible with previously reported resonance structure around E = 2.1 MeV. The data were limited at low energies by low count rates as well as possible background contributions. This experiment extends the previously achieved low-energy measurement by charged particle spectroscopy to 2 MeV, which corresponds to the high-energy side of the astrophysically relevant temperature. Present knowledge of level structures and nonresonant contribution cannot explain the results of the present experiment, which may change the C-12 + C-12 reaction rate significantly. Despite the progress decreasing the low-energy limit, any extrapolation into the astrophysical energy range remains highly uncertain based on available experimental data.

The western Calabria region is characterized by high relief rocky coasts alternating with large plains, such as the St Eufemia plain. The Holocene history of this plain has been reconstructed by integrating morphostratigraphic, chronostratigraphic and palaeoenvironmental analyses. A new core, 20-m long, drilled in the modern plain and chronologically constrained through ten 14 C datings, proved to cover the last 9500 years. Micropaleontological and sedimentological analyses, coupled with palynological investigation, allowed the evolution of the environments to be reconstructed in detail. During the early Holocene, an open lagoon established along the coast over the alluvial environment left by the late Pleistocene sea level low stand. At ca. 8600 yr BP the growth of barrier ridges drove the development of marshy areas, bounded at their back by a Pleistocene marine terrace +30/40 m high. Humid conditions, with small lakes and wetlands, persisted in the narrow coastal plain along the middle-late Holocene. Between 2500 and 1500 yr BP, the increase in the alluvial and littoral sedimentation triggered the final phase of coastline progradation. Comparison between the sedimentary evolution of the St Eufemia plain and the Holocene sea-level rise history sheds lights on the tectonic behavior of this coastal sector which seems to have experienced a more intense uplift in the early Holocene and a tendency to stability in the middle-late Holocene.

Background: The origin of fluorine is a widely debated issue. Nevertheless, the 15N(α,γ)19F reaction is a common feature among the various production channels so far proposed. Its reaction rate at relevant temperatures is determined by a number of narrow resonances together with the direct capture and the tails of the two broad resonances at Ec.m.=1323 and 1487 keV. Purpose: The broad resonances widths, Γγ and Γα, have to be measured with adequate precision in order to better determine their contribution to the 15N(α,γ)19F stellar reaction rate. Methods: Measurement through the direct detection of the 19F recoil ions with the European Recoil separator for Nuclear Astrophysics (ERNA) were performed. The reaction was initiated by a 15N beam impinging onto a 4He windowless gas target. The observed yield of the resonances at Ec.m.=1323 and 1487 keV is used to determine their widths in the α and γ channels. Results: We show that a direct measurement of the cross section of the 15N(α,γ)19F reaction can be successfully obtained with the recoil separator ERNA, and the widths Γγ and Γα of the two broad resonances have been determined. While a fair agreement is found with earlier determination of the widths of the 1487 keV resonance, a significant difference is found for the 1323 keV resonance Γα. Conclusions: The revision of the widths of the two more relevant broad resonances in the 15N(α,γ)19F reaction presented in this work is the first step toward a more firm determination of the reaction rate. At present, the residual uncertainty at the temperatures of the 19F stellar nucleosynthesis is dominated by the uncertainties affecting the direct capture component and the 364 keV narrow resonance, both so far investigated only through indirect experiments.

Background: The origin of fluorine is a widely debated issue. Nevertheless, the N15(α,γ)F19 reaction is a common feature among the various production channels so far proposed. Its reaction rate at relevant temperatures is determined by a number of narrow resonances together with the direct capture and the tails of the two broad resonances at Ec.m.=1323 and 1487 keV. Purpose: The broad resonances widths, Γγ and Γα, have to be measured with adequate precision in order to better determine their contribution to the N15(α,γ)F19 stellar reaction rate. Methods: Measurement through the direct detection of the F19 recoil ions with the European Recoil separator for Nuclear Astrophysics (ERNA) were performed. The reaction was initiated by a N15 beam impinging onto a He4 windowless gas target. The observed yield of the resonances at Ec.m.=1323 and 1487 keV is used to determine their widths in the α and γ channels. Results: We show that a direct measurement of the cross section of the N15(α,γ)F19 reaction can be successfully obtained with the recoil separator ERNA, and the widths Γγ and Γα of the two broad resonances have been determined. While a fair agreement is found with earlier determination of the widths of the 1487 keV resonance, a significant difference is found for the 1323 keV resonance Γα. Conclusions: The revision of the widths of the two more relevant broad resonances in the N15(α,γ)F19 reaction presented in this work is the first step toward a more firm determination of the reaction rate. At present, the residual uncertainty at the temperatures of the F19 stellar nucleosynthesis is dominated by the uncertainties affecting the direct capture component and the 364 keV narrow resonance, both so far investigated only through indirect experiments.

This paper concerns the relative sea-level changes associated with the Atlantic Patagonian coast derived from sea-level index points whose elevation was determined by a differential global position system (DGPS). Bio encrustations from outcrops located near Camarones, Chubut, Argentina, consist of autochthonous deposits characterized by Austromegabalanus psittacus (Molina, 1782), encrusting acer vulinid foraminifera, coralline red algae and bryozoans. The association of the different organisms is interpreted as being associated with an intertidal environment, and they have been used as index points to establish the relative sea-level position. The main conclusion is that the relative sea-level between c. 7000 and 5300 cal. yr BP was in the range ofc. 2?4 m a.s.l., with a mean value of c. 3.5 m a.s.l. Our data seem to support the existence of different rates of relative sea-level fall in different sectors of Atlantic Patagonia during the Holocene and highlight the importance of a more precise and accurate relative sea-level estimation by producing new data and revisiting the indicative meaning of most of the indicators so far used in the area., Facultad de Ciencias Naturales y Museo

The nucleosynthesis of light elements, from helium up to silicon, mainly occurs in Red Giant and Asymptotic Giant Branch stars and Novae. The relative abundances of the synthesized nuclides critically depend on the rates of the nuclear processes involved, often through non-trivial reaction chains, combined with complex mixing mechanisms. In this review, we summarize the contributions made by LUNA experiments in furthering our understanding of nuclear reaction rates necessary for modeling nucleosynthesis in AGB stars and Novae explosions., 23 pages, 12 figures

The origin of fluorine is a widely debated issue. Nevertheless, the ^{15}N({\alpha},{\gamma})^{19}F reaction is a common feature among the various production channels so far proposed. Its reaction rate at relevant temperatures is determined by a number of narrow resonances together with the DC component and the tails of the two broad resonances at E_{c.m.} = 1323 and 1487 keV. Measurement through the direct detection of the 19F recoil ions with the European Recoil separator for Nuclear Astrophysics (ERNA) were performed. The reaction was initiated by a 15N beam impinging onto a 4He windowless gas target. The observed yield of the resonances at Ec.m. = 1323 and 1487 keV is used to determine their widths in the {\alpha} and {\gamma} channels. We show that a direct measurement of the cross section of the ^{15}N({\alpha},{\gamma})^{19}F reaction can be successfully obtained with the Recoil Separator ERNA, and the widths {\Gamma}_{\gamma} and {\Gamma}_{\alpha} of the two broad resonances have been determined. While a fair agreement is found with earlier determination of the widths of the 1487 keV resonance, a significant difference is found for the 1323 keV resonance {\Gamma}_{\alpha} . The revision of the widths of the two more relevant broad resonances in the 15N({\alpha},{\gamma})19F reaction presented in this work is the first step toward a more firm determination of the reaction rate. At present, the residual uncertainty at the temperatures of the ^{19}F stellar nucleosynthesis is dominated by the uncertainties affecting the Direct Capture component and the 364 keV narrow resonance, both so far investigated only through indirect experiments., Comment: 8 pages, 11 figures. Accepted for publication in PRC

Background: The origin of fluorine is a widely debated issue. Nevertheless, the 15N(α ,γ )19F reaction is a common feature among the various production channels so far proposed. Its reaction rate at relevant temperatures is determined by a number of narrow resonances together with the direct capture and the tails of the two broad resonances at Ec .m .=1323 and 1487 keV. Purpose: The broad resonances widths, Γγ and Γα, have to be measured with adequate precision in order to better determine their contribution to the 15N(α ,γ )19F stellar reaction rate. Methods: Measurement through the direct detection of the 19F recoil ions with the European Recoil separator for Nuclear Astrophysics (ERNA) were performed. The reaction was initiated by a 15N beam impinging onto a 4He windowless gas target. The observed yield of the resonances at Ec .m .=1323 and 1487 keV is used to determine their widths in the α and γ channels. Results: We show that a direct measurement of the cross section of the 15N(α ,γ )19F reaction can be successfully obtained with the recoil separator ERNA, and the widths Γγ and Γα of the two broad resonances have been determined. While a fair agreement is found with earlier determination of the widths of the 1487 keV resonance, a significant difference is found for the 1323 keV resonance Γα. Conclusions: The revision of the widths of the two more relevant broad resonances in the 15N(α ,γ )19F reaction presented in this work is the first step toward a more firm determination of the reaction rate. At present, the residual uncertainty at the temperatures of the 19F stellar nucleosynthesis is dominated by the uncertainties affecting the direct capture component and the 364 keV narrow resonance, both so far investigated only through indirect experiments.

The origin of fluorine is a widely debated issue. Nevertheless, the ^{15}N(��,��)^{19}F reaction is a common feature among the various production channels so far proposed. Its reaction rate at relevant temperatures is determined by a number of narrow resonances together with the DC component and the tails of the two broad resonances at E_{c.m.} = 1323 and 1487 keV. Measurement through the direct detection of the 19F recoil ions with the European Recoil separator for Nuclear Astrophysics (ERNA) were performed. The reaction was initiated by a 15N beam impinging onto a 4He windowless gas target. The observed yield of the resonances at Ec.m. = 1323 and 1487 keV is used to determine their widths in the �� and �� channels. We show that a direct measurement of the cross section of the ^{15}N(��,��)^{19}F reaction can be successfully obtained with the Recoil Separator ERNA, and the widths ��_�� and ��_�� of the two broad resonances have been determined. While a fair agreement is found with earlier determination of the widths of the 1487 keV resonance, a significant difference is found for the 1323 keV resonance ��_�� . The revision of the widths of the two more relevant broad resonances in the 15N(��,��)19F reaction presented in this work is the first step toward a more firm determination of the reaction rate. At present, the residual uncertainty at the temperatures of the ^{19}F stellar nucleosynthesis is dominated by the uncertainties affecting the Direct Capture component and the 364 keV narrow resonance, both so far investigated only through indirect experiments., 8 pages, 11 figures. Accepted for publication in PRC

Studying atmospheric neutrino oscillations in the few-GeV range with a multimegaton detector promises to determine the neutrino mass hierarchy. This is the main science goal pursued by the future KM3NeT/ORCA water Cherenkov detector in the Mediterranean Sea. In this paper, the processes that limit the obtainable resolution in both energy and direction in charged-current neutrino events in the ORCA detector are investigated. These processes include the composition of the hadronic fragmentation products, the subsequent particle propagation and the photon-sampling fraction of the detector. GEANT simulations of neutrino interactions in seawater produced by GENIE are used to study the effects in the 1-20 GeV range. It is found that fluctuations in the hadronic cascade in conjunction with the variation of the inelasticity y are most detrimental to the resolutions. The effect of limited photon sampling in the detector is of significantly less importance. These results will therefore also be applicable to similar detectors/media, such as those in ice.

The knowledge of the mechanisms regulating the concentration of nutrients in rivers is of fundamental importance in maintaining the ecological functioning of streams. In particular, in the riverbed sediments, where the biogeochemical activity is enhanced, the study of retention mechanisms becomes crucial in order to determine the restoring capacity of a watercourse. In case of groundwater inflow, hot-spots in the recycling of nutrients within the riparian and hyporheic zones can be observed, influencing the nutrient load transported into the stream depending on retention mechanisms. Hence, the study of biotic and abiotic factors affecting retention within the riverbed sediments, and the study of processes occurring at the interface of groundwater and surface water (i.e., the hyporheic zone) are fundamental in understanding the mechanisms of retention and transport, which regulate the concentration of nutrients, and in particular nitrates, in streams. The main scope of the present project, within the framework of the IAEA Coordinated Research Project (CRP)“Environmental Isotopes and Age Dating Methods to Assess Nitrogen Pollution and Other Quality Issues in Rivers”, is to find a reliable methodology to, spatially and temporally, quantify groundwater inflows to a river in order to study nitrates contamination of a groundwater dependent river ecosystem. This goal will be achieved focusing on three main objectives: 1. The identification and quantification of spatio-temporal variation of the connectivity between groundwater and surface water in the considered river basin. 2. The identification of the nitrate contamination sources of shallow groundwater in the considered alluvial aquifer. 3. The study of the nitrates retention and recycling mechanisms in riverbed sediments in critical effluent river reaches (key sites) in order to determine the importance of hyporheic and riparian zones in the considered catchment. Here, the preliminary results of the hydrogeologic, chemical and isotopic monitoring are presented and discussed.

Accelerator mass spectrometry (AMS) is presently the most sensitive technique for the measurement of long-lived actinides, e.g. 236U and 239Pu. A new actinide line is in operation at the Center for Isotopic Research on Cultural and Environmental heritage (CIRCE) in Caserta, Italy. Using the actinide line a uranium mass sensitivity of around 4 μg has been reached measuring with a 16-strip silicon detector, and a 239Pu background level of below 0.1 fg has been obtained. In this work we also discuss preliminary results for environmental and structural samples from in and around the Garigliano nuclear power plant (GNPP), presently in the decommissioning phase. Measurements on environmental samples from the vicinity of the plant allow the assessment of contamination, if any, over the years. Measurements of structural samples from the plant are relevant to the optimization of the decommissioning program for the GNPP.

The KM3NeT research infrastructure, currently under construction in the Mediterranean Sea, will host neutrino telescopes for the identification of neutrino sources in the Universe and for studies of the neutrino mass hierarchy. These telescopes will house hundreds of thousands of photomultiplier tubes that will have to be operated in a stable and reliable fashion. In this context, the stability of the dark counts has been investigated for photomultiplier tubes with negative high voltage on the photocathode and held in insulating support structures made of 3D printed nylon material. Small gaps between the rigid support structure and the photomultiplier tubes in the presence of electric fields can lead to discharges that produce dark count rates that are highly variable. A solution was found by applying the same insulating varnish as used for the high voltage bases directly to the outside of the photomultiplier tubes. This transparent conformal coating provides a convenient and inexpensive method of insulation. © 2016 IOP Publishing Ltd and Sissa Medialab srl.

The 15N(p,g)16O reaction represents a break out reaction linking the first and second cycle of the CNO cycles redistributing the carbon and nitrogen abundances into the oxygen range. The reaction is dominated by two broad resonances at Ep = 338 keV and 1028 keV and a Direct Capture contribution to the ground state of 16O. Interference effects between these contributions in both the low energy region (Ep < 338 keV) and in between the two resonances (338, Comment: 15 pages, 9 figures

Proton captures on Mg isotopes play an important role in the Mg-Al cycle active in stellar H-shell burning. In particular, the strengths of low-energy resonances with E