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Carbon fusion reactions 12 C( 12 C,p) 23 Na and 12 C( 12 C, α ) 20 Ne play a key role in the evolution of massive stars and in explosive scenarios such as type-Ia supernovae and super-bursts in binary stars. A direct determination of their cross sections is extremely challenging and discrepancies exist between different data sets in the literature. Here we report the results of a direct measurement performed at the CIRCE Tandem Accelerator Laboratory in Caserta (Italy), using Δ E - E detectors for unambiguous charge identification. Cross sections were measured in the energy range E c. m. = 2.51 - 4.36 MeV with energy steps between 10 and 25 keV in the centre of mass. To our knowledge these represent the finest energy steps to date. Results are presented in the form of partial and summed astrophysical S ~ -factors for individual proton- and α -particle channels. Branching ratios of individual proton- and α -particle groups were found to vary significantly with energy. Angular distributions, albeit limited to three angles, were also found to be non-isotropic, which could be a potential explanation for the discrepancies observed among different data sets. Further efforts are ongoing to extend measurements to lower energies. [ABSTRACT FROM AUTHOR]

Carbon fusion reactions 12 C( 12 C,p) 23 Na and 12 C( 12 C, α ) 20 Ne play a key role in the evolution of massive stars and in explosive scenarios such as type-Ia supernovae and super-bursts in binary stars. A direct determination of their cross sections is extremely challenging and discrepancies exist between different data sets in the literature. Here we report the results of a direct measurement performed at the CIRCE Tandem Accelerator Laboratory in Caserta (Italy), using Δ E - E detectors for unambiguous charge identification. Cross sections were measured in the energy range E c. m. = 2.51 - 4.36 MeV with energy steps between 10 and 25 keV in the centre of mass. To our knowledge these represent the finest energy steps to date. Results are presented in the form of partial and summed astrophysical S ~ -factors for individual proton- and α -particle channels. Branching ratios of individual proton- and α -particle groups were found to vary significantly with energy. Angular distributions, albeit limited to three angles, were also found to be non-isotropic, which could be a potential explanation for the discrepancies observed among different data sets. Further efforts are ongoing to extend measurements to lower energies. [ABSTRACT FROM AUTHOR]

Rationale: Past climate has always influenced human adaptation to the environment. In order to reconstruct palaeoclimate fluctuations and their role in the evolution of Near Eastern societies during the mid‐Holocene, high‐resolution Δ13C records from fossil wood remains at the archaeoloical site of Arslantepe (eastern Turkey) have been developed. Methods: After chemical treatment, δ13C values were measured by sample combustion flow using a FLASH EA‐CHNS instrument interfaced with a Delta V isotope ratio mass spectrometer via a CONFLO III. Two replicates per sample were analysed. The measurement precision was evaluated by propagating variations of the δ13C values of samples and V‐PDB standards, whereas the accuracy was checked by a quality control sample. To account for changes in atmospheric CO2, Δ13C values were calculated. In addition, 14C/12C ratios were measured by means of an AMS system (3 MV tandem accelerator). Results: Mean Δ13C curves of deciduous Quercus and Juniperus from archaeological levels between 4700 and 2000  bc (Arslantepe periods VIII‐VI D) were produced, where the isotope values were ordered by the available Radiocarbon ages. Interspecific variations of evergreen vs deciduous plants were postulated for the juniper Δ13C values being higher than 3‰. The seasonal rainfall amount was recorded by the juniper remains, while the water table levels were obtained from the oak samples. Conclusions: The local climate experienced times of enhanced/reduced precipitation in concert with regional trends. Anomalies in the air mass circulation from the Mediterranean basin also produced oscillations of rainfall amount. In such a frame the Rapid Climate Change dry events had a consistent signature in the Arslantepe Δ13C record, thus potentially contributing to social or organisational changes at the site. [ABSTRACT FROM AUTHOR]

Retraction Note: Direct measurements of the 12C + 12C reactions cross-sections towards astrophysical energies After publication, we discovered a mistake in the script used to calculate beam energy losses from tabulated stopping powers. We deeply regret any inconvenience that this retraction may cause, and we apologize to the scientific community and to the readers of EPJA for any harm that may have been caused by the publication of this paper. [Extracted from the article]

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 paper, 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. [ABSTRACT FROM AUTHOR]

The question of whether the rise in CO2 levels observed during the industrial era has influenced the rates of tree biomass growth represents one of the main unsolved questions in the field of climate change science. In this framework, the African tropical forest represents one of the most important carbon (C) sinks, but detailed knowledge of its response to elevated CO2 is still lacking, especially regarding tree growth rate estimations. A major limitation to determining growth rates in the African tropical region is that many trees lack seasonality in cambial activity determining annual growth rings. In this study, several species of trees characterizing the African tropical forest have been investigated to estimate their biomass growth rate by means of a procedure based on 14C and growth models. A total of 71 subsamples were analyzed for a Entandrophragma cylindricum (sapele) tree, and 38 and 25 wood subsamples for Erythrophleum suaveolens (tali) and Triplochiton scleroxylon (ayous) trees, respectively, using radiocarbon measurements at the Centre for Isotopic Research on Cultural and Environmental Heritage (CIRCE). All measured modern samples were in agreement with the Southern Hemisphere (SH) 14C bomb-spike curve. Observed preliminary results indicate a decrease in the growth rate of the sapele tree (~350 yr old) in the industrial period compared to the pre-industrial era. Growth rates for trees of the other 2 species were higher than sapele, with ayous being the fastest-growing species. [ABSTRACT FROM AUTHOR]

The assessment of the radiological impact of a decommissioned nuclear power plant is presented here through the results of an environmental monitoring survey carried out in the area surrounding the Garigliano Power Plant. The levels of radioactivity in soil, water, air and other environmental matrices are shown, in which α, β and γ activity and the γ equivalent dose rate are measured. Radioactivity levels of the samples from the Garigliano area are analyzed and then compared with those from a control zone situated more than 100 km away. Moreover, a comparison is made with a previous survey carried out in 2001. The analyses and comparisons show no significant alteration in the radiological characteristics of the area surrounding the plant, with the overall radioactivity depending mainly on the global fallout and natural sources. [ABSTRACT FROM AUTHOR]

The paper presents new and important 14C data from eight Eneolithic sites in Campania measured at the Centre for Isotopic Research of Cultural and Environmental Heritage (CIRCE) AMS laboratory in Caserta (Italy). Twenty-four 14C determinations on bone and charcoal are used here for chronological reconstruction of human habitation and dating of some volcanic eruptions affecting the settlement activity. Our research has shed new light on absolute chronology of the whole Campanian Eneolithic, a period of profound cultural transformations triggered by introduction and use of metals, in particular copper. [ABSTRACT FROM AUTHOR]

We show the potentiality of coupling together different compound-specific isotopic analyses in a laboratory experiment, where 13C-depleted leaf litter was incubated on a 13C-enriched soil. The aim of our study was to identify the soil compounds where the C derived from three different litter species is retained. Three 13C-depleted leaf litter ( Liquidambar styraciflua L., Cercis canadensis L. and Pinus taeda L., δ13CvsPDB ≈ −43‰), differing in their degradability, were incubated on a C4 soil (δ13CvsPDB ≈ −18‰) under laboratory-controlled conditions for 8 months. At harvest, compound-specific isotope analyses were performed on different classes of soil compounds [i.e. phospholipids fatty acids (PLFAs), n-alkanes and soil pyrolysis products]. Linoleic acid (PLFA 18:2ω6,9) was found to be very depleted in 13C (δ13CvsPDB ≈ from −38 to −42‰) compared to all other PLFAs (δ13CvsPDB ≈ from −14 to −35‰). Because of this, fungi were identified as the first among microbes to use the litter as source of C. Among n-alkanes, long-chain (C27–C31) n-alkanes were the only to have a depleted δ13C. This is an indication that not all of the C derived from litter in the soil was transformed by microbes. The depletion in 13C was also found in different classes of pyrolysis products, suggesting that the litter-derived C is incorporated in less or more chemically stable compounds, even only after 8 months decomposition. [ABSTRACT FROM AUTHOR]

During microbial breakdown of leaf litter a fraction of the C lost by the litter is not released to the atmosphere as CO2 but remains in the soil as microbial byproducts. The amount of this fraction and the factors influencing its size are not yet clearly known. We performed a laboratory experiment to quantify the flow of C from decaying litter into the soil, by means of stable C isotopes, and tested its dependence on litter chemical properties. Three sets of 13C-depleted leaf litter ( Liquidambar styraciflua L., Cercis canadensis L. and Pinus taeda L.) were incubated in the laboratory in jars containing 13C-enriched soil (i.e. formed C4 vegetation). Four jars containing soil only were used as a control. Litter chemical properties were measured using thermogravimetry (Tg) and pyrolysis–gas chromatography/mass spectrometry–combustion interface–isotope ratio mass spectrometry (Py–GC/MS–C–IRMS). The respiration rates and the δ13C of the respired CO2 were measured at regular intervals. After 8 months of incubation, soils incubated with both L. styraciflua and C. canadensis showed a significant change in δ13C (δ13Cfinal = −20.2 ± 0.4‰ and −19.5 ± 0.5‰, respectively) with respect to the initial value (δ13Cinitial = −17.7 ± 0.3‰); the same did not hold for soil incubated with P. taeda (δ13Cfinal:−18.1 ± 0.5‰). The percentages of litter-derived C in soil over the total C loss were not statistically different from one litter species to another. This suggests that there is no dependence of the percentage of C input into the soil (over the total C loss) on litter quality and that the fractional loss of leaf litter C is dependent only on the microbial assimilation efficiency. The percentage of litter-derived C in soil was estimated to be 13 ± 3% of total C loss. [ABSTRACT FROM AUTHOR]

7Be decays via electron capture and therefore its half-life is expected to depend on the electron density at the nucleus. We measured the 7Be half-life in palladium, tungsten, zirconium and tantalum metals, in order to investigate the influence of the quasi-free electrons in metals on the probability of electron capture. The 7Be samples were obtained implanting a 4.85MeV pure radioactive 7Be ion beam. The 7Be half-life was determined measuring the 478keV gamma decay following the electron capture by means of HPGe detectors. In order to reduce systematic errors, we planned to perform independent measurements in three different laboratories: Naples (Italy), Bochum (Germany) and Debrecen (Hungary). On the basis of the first results, we do not find a 7Be half-life change within the experimental errors of 0.4%. [ABSTRACT FROM AUTHOR]

The total cross-section of 12C(α,γ)16O was measured for the first time by a direct and ungated detection of the 16O recoils. This measurement in inverse kinematics using the recoil mass separator ERNA in combination with a windowless He gas target allowed to collect data with high precision in the energy range E = 1.9 to 4.9 MeV. The data represent new information for the determination of the astrophysical S( E) factor. [ABSTRACT FROM AUTHOR]

Background: Several studies have confirmed the equivalence of the microvolt T-wave alternans (mTWA) and the electrophysiology (EPS) tests in cardiac disease. No data are available in populations of competitive athletes with arrhythmias that might jeopardize the pursuit of their professional career.Methods: We prospectively studied 100 trained competitive athletes, including elite types (72/100), (mean age +/- standard deviation: 26.1 +/- 4.5 years). Forty-eight of them were wholly normal (Group A, mean age: 24.5 +/- 8.5 years) and 52 of them had severe arrhythmias (Group B, mean age: 28.2 +/- 11.5 years) and were symptomatic in 85% of cases for prolonged palpitations and syncope, but lacked any overt structural heart disease at standardized cardiological screening. All athletes were evaluated with the microvolt T-wave alternans exercise-stress test, using the Heart Wave System with Microvolt Sensors. Group B underwent EPS to evaluate inducibility to sustained ventricular tachycardia (VT) during programmed electrical stimulation.Results: In Group A, the mTWA outcome was determinate in 45 subjects (94%) and indeterminate in 3 (6%). No symptomatic event was reported in a follow-up of 36.1 months. In Group B, the mTWA test was positive in 7 symptomatic subjects (15%), indeterminate in 3 (7%), and negative for the remaining 42 subjects (76%). Forty-one of 42 negative mTWA subjects were also negative in the EPS test, without any syncope or sustained VT during 25.3 months of follow-up. In the positive mTWA test subjects, 5 (72%) were positive for inducibility of rapid sustained monomorphic VT in EPS, 1 was positive for severe sustained atrial tachyarrhythmias, and 1 refused EPS. We were able to pronounce a correct diagnosis of lymphocytic myocarditis for only 1 mTWA and EPS-positive subject. For the other 4 positive patients with arrhythmogenic micropathology, severe arrhythmic events were revealed in the follow-up and aggressive hybrid treatment was necessary.Conclusion: Microvolt-TWA study seems to be a useful, noninvasive, and feasible tool for evaluating arrhythmic risk in the athletic population. The mTWA test showed a high negative predictive value, using both EPS and the follow-up observation for severe arrhythmic cardiac events as an endpoint. The positive predictive value was present in a limited number of cases that were, however, subjects with a high risk of sudden arrhythmic death. [ABSTRACT FROM AUTHOR]

For improved measurements of the key astrophysical reaction 12C(α,γ)16O in inverted kinematics, a recoil separator ERNA is being developed at the 4 MV Dynamitron tandem accelerator in Bochum to detect directly the 16O recoils with about 50% efficiency. Calculations of the ion beam optics including all filtering and focusing elements of ERNA are presented. Since the 12C projectiles and the 16O recoils have essentially the same momentum, and since the 12C ion beam emerging from the accelerator passes through a momentum filter (analysing magnet), the 12C ion beam must be as free as possible from 16O contamination for ERNA to succeed. In the present work, the 16O contamination was reduced from a level of 1 × 10−11 to a level below 2 × 10−29 by the installation of Wien filters both before and after the analysing magnet. The measurement of these and other beam specifications involved other parts of the final ERNA layout – sequentially a Wien filter, a 60˚ dipole magnet, another Wien filter, and a ΔE-E telescope. The setup led to a measured suppression factor of 5 × 10−18 for the 12C ion beam. The experiments also indicate that an almost free choice of the charge state for the 16O recoils is possible in the separator. [ABSTRACT FROM AUTHOR]

Particle-γ coincidence measurements were carried out for the systemNe+Ni at 44 MeV/A. Discrete lines in the coincidence and singles γ-ray spectra were attributed to transitions between low-spin levels of residual nuclei with masses between A = 46 and A = 60. The associated particle multiplicities were found to increase with decreasing mass number. The results are discussed in the framework of a « participant-spectator » model for the reaction mechanism. [ABSTRACT FROM AUTHOR]

The lifetimes of nine levels inF have been measured by using the DSAM and theHe(O, p)F inverse reaction at 21 MeV incident energy on Al backings. Particle-gamma coincidence was employed. Levels (MeV) and corresponding lifetime (ps) deduced by a line shape analysis are as follows: 1.70 (0.897±0.057), 2.10 (4.93±0.78), 2.52 (0.554±0.045), 3.06 (<0.004), 3.13 (0.343±0.022), 3.36 (0.451±0.034), 3.72 (<0.007), 3.79 (1.90±0.20) and 3.84 (0.021±0.004). [ABSTRACT FROM AUTHOR]

The lifetime of the 1.701 MeV level inF has been measured with the DSAM by means of the inverseHe(O, p) reaction at 15, 18 and 21 MeV incident energy, on Ta and Al backings. Dependence of the extracted values on incident energy and stopping material has been found. It is shown that both effects can be explained as due to cascade feeding from higher levels. [ABSTRACT FROM AUTHOR]

The absolute cross section σ of the d(Li, p)Li reaction near the E =0.61 MeV resonance has been measured using aLi ion beam and a windowless gas target system filled with D gas. The proton yield of the reaction and the β-delayed α-activity of the residual nuclidesLi were observed both concurrently with the elastic scattering yield, relating σ to the Rutherford scattering cross section σ . The resulting values, σ (from p)=143.6±8.9 mb and σ (fromLi)=151±20 mb, lead to a weighted mean value of σ=153±6 mb ( x =2.26) including all available values and σ=146±5 mb ( x =0.05) removing some values from the data set. The consequences for the expected flux of high-energy solar neutrinos are discussed. [ABSTRACT FROM AUTHOR]

γ-rays are measured in coincidence with the dissipative complex fragments from theCl +Ni reaction at 7.7 A MeV. Theoretical γ-ray coincidence spectra are determined through a fitting procedure using the contribution of the excited fragment statistical γ-decay calculated by means of the CASCADE code. Whereas the expected statistical spectra fit very well the data in the energy region E=2 to 8 MeV, above this energy another emission mechanism in addition to the statistical decay has to be considered in order to reproduce the experimental spectra. Simulations based on the Vlasov equation suggest that this emission could come from the decay of dipole strength excited in the intermediate dinuclear system. [ABSTRACT FROM AUTHOR]

TheSi+Ni reaction at 163.8 MeV incident energy is studied by measuring in coincidence γ-rays and charged particles identified from Z=2 to Z=16. The transition from quasi-elastic to more damped reactions is observed when the difference between the detected charge and the projectile one is increased. The strong influence of the particle decay on the measured γ-ray multiplicity is evidenced with the help of the statistical model computer code CASCADE. Dissipative events are well described in the rolling limit with excitation energy equally shared between the fragments. The overall agreement is lost for the fragments with the projectile charge which show a small value of the γ-multiplicity even for dissipative events. This is probably connected with the previously observed non statistical behavior of gamma rays emitted in coincidence with projectile-like fragments. In the alpha-spectrum measured in coincidence with gamma-rays, the deexcitation of fused systems is clearly separated from in flight emission of deep inelastic fragments. The low measured gamma-ray multiplicity for fusion events is qualitatively explained taking into account the effect of alpha-emission in the statistical decay. [ABSTRACT FROM AUTHOR]

It is shown that the Partially Overlapping Molecular Level Model (POMLM) accounts for the experimental results of the dissipativeSi +Ti collision around 210 MeV incident energy. The general trend of the properties of the fluctuations as well as the average angular distributions are reproduced by the same set of main parameters. A general consistency is also found between the present data and the data obtained in previous work on the same colliding system performed at lower incident energy (around 123 MeV). [ABSTRACT FROM AUTHOR]

An in-beam γ-ray study performed with theCd(Si, p 3 n) reaction has established the structure of the N=79 nucleusPm. States up to I=(20) ħ and 5.5 MeV excitation energy have been recognized above the 5.95 m isomeric state which we identify, from the GT decay toNd, as the 8 member of the ( πd vh) multiplet, changing the present 7 assignment. The low energy part of the level scheme is discussed in terms of the coupling of the valence holes in respect to the Z=64, N=82 shell closure. A new 8 isomeric state with t=1 ns has been observed, having most likely a ( πh vh) configuration. [ABSTRACT FROM AUTHOR]

Copyright of Il Nuovo Cimento: A is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Il Nuovo Cimento: A is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Il Nuovo Cimento: A is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The absolute cross section σ (E) of the radiative capture reaction p(7Be,γ)8B at the center-of-mass energy E = 992 keV has been measured using a radioactive 7Be ion beam and a windowless gas target system filled with H2 gas. The 8B residual nuclides were detected with a recoil separator consisting of momentum and velocity filters and a ΔE-E detector telescope. The 8B yield was observed concurrently with the 7Be + p elastic scattering yield, relating σ(E) to the Rutherford scattering cross section. The resulting value, σ(E) = 0.41 ± 0.11 μb, leads to an S(E) factor at zero energy of S(0) = 16 ± 4 eV b, in fair agreement with recommended values. [ABSTRACT FROM AUTHOR]

For an improved determination of theBe( p, γ)B absolute cross section, the reaction is studied in inverse kinematics. The study involves aBe radioactive ion beam of 8.0 MeV, a windowless H gas target, and an efficient recoil separator for the detection of theB residual nuclides. The techniques used to produce such a beam as well as the first direct observation ofB are reported. [ABSTRACT FROM AUTHOR]

The loss of 8Li recoil nuclei in 7Li(d,p)8Li has been measured using different backings and 7LiF target thicknesses as well as different deuteron energies. The results confirm essentially recent TRIM calculations. The losses are large (about 13%) for the combination of thin targets and heavy backings at Ed=0.80 MeV and increase with decreasing deuteron energy. The implications on the cross sections for 7Li(d,p)8Li and 7Be(p,γ)8B are discussed. [ABSTRACT FROM AUTHOR]

The 12C(12C,p)23Na and 12C(12C,α)20Ne fusion reactions are among the most important in stellar evolution since they determine the destiny of massive (M≃8-10M⊙) stars. However, experimental low-energy investigations of such reactions are significantly hampered by ubiquitous natural hydrogen and deuterium contaminants in the carbon targets. The associated beam-induced background completely masks the reaction products of interest thus preventing cross-section measurements at the relevant energies of astrophysical interest, E cm <2 MeV. In this work, we report about an investigation aimed at assessing possible deuterium reductions on both natural graphite and Highly Ordered Pyrolytic Graphite targets as a function of target temperature. Our results indicate that reductions up to about 80% can be attained on both targets in the temperature range investigated, T≃200-1200∘C. A further reduction by a factor of 2.5 in absolute deuterium content is observed when the scattering chamber is surrounded by a dry nitrogen atmosphere so as to minimise light-particles uptake within the chamber rest gas (and thus on target) through air leaks. The results from this study will inform the choice of optimal experimental conditions and procedures for improved measurements of the 12C + 12C reactions cross-sections at the low energies of astrophysical interest. [ABSTRACT FROM AUTHOR]

For the β+-decay of 22Na in the metallic environment Pd cooled to T = 12 K the 22Na half-life was observed to be shorter by 1.2±0.2%. The result is consistent with --but lower than-- the prediction of the Debye plasma model. [ABSTRACT FROM AUTHOR]

An in-beam γ-ray study performed with theCd(Si,p3n) reaction has established the high-spin states up to 5 MeV excitation energy and I=(21)ħ in the N=79 nucleusPm. The low energy part of the level scheme shows both positive and negative parity states which are interpreted as single particle excitations in the 2d and 1h orbitals. The level scheme is in qualitative agreement with the coupling of the odd particles to the known yrast levels of the appropriate core nuclei. [ABSTRACT FROM AUTHOR]

The production cross sections ofLi in its ground and first excited states have been measured at 14°, 120°, 150°, for the 742 MeVNe+Ni reaction. Hauser-Feshbach calculations show that the backward angle data are consistent with an emission temperature greater than 6 MeV. This is in agreement with the values extracted from the slope of the energy spectra and indicates that the emitting source is equilibrated. [ABSTRACT FROM AUTHOR]