A5071518998- Nuclear physics research studies
- Nuclear Physics and Applications
- Astro and Planetary Science
- Stellar, planetary, and galactic studies
- Astronomical and nuclear sciences
- Atomic and Molecular Physics
- Gamma-ray bursts and supernovae
- Particle physics theoretical and experimental studies
- Quantum Chromodynamics and Particle Interactions
- Advanced Chemical Physics Studies
- Nuclear reactor physics and engineering
- High-pressure geophysics and materials
- Astronomy and Astrophysical Research
- X-ray Spectroscopy and Fluorescence Analysis
- Laser-induced spectroscopy and plasma
- Planetary Science and Exploration
- Geomagnetism and Paleomagnetism Studies
- Neutrino Physics Research
- Genetic factors in colorectal cancer
- Chemical Reactions and Isotopes
- Scientific Research and Discoveries
- Boron Compounds in Chemistry
- Laser-Plasma Interactions and Diagnostics
- High-Energy Particle Collisions Research
- Geological and Geochemical Analysis
Istituto Nazionale di Fisica Nucleare, Sezione di Perugia
2014-2023
University of Perugia
2014-2023
Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud
2012-2020
Istituto Nazionale di Fisica Nucleare
2012-2020
Arcetri Astrophysical Observatory
2015
Karlsruhe Institute of Technology
2015
Recent spectroscopic measurements in open clusters younger than the Sun with [Fe/H] ≳ 0 showed that abundances of neutron-rich elements have continued to increase Galaxy after formation Sun, roughly maintaining a solar-like distribution. This growth requires neutron fluences larger those so far assumed, as these would too few neutrons per iron seed. We suggest observed enhancements can be produced by nucleosynthesis asymptotic giant branch (AGB) stars low mass (M < 1.5 M☉) if they release...
ABSTRACT Slow neutron captures are responsible for the production of about 50% elements heavier than iron, mainly occurring during asymptotic giant branch phase low-mass stars (1 ≲ M / ⊙ 3), where main source is 13 C( α , n ) 16 O reaction. This last reaction activated from locally produced C, formed by partial mixing hydrogen into He-rich layers. We present here first attempt to describe a physical mechanism formation C reservoir, studying mass circulation induced magnetic buoyancy without...
The 13C(α, n)16O reaction is the neutron source for main component of s-process, responsible production most nuclei in mass range 90 ≲ A 208. This takes place inside helium-burning shell asymptotic giant branch stars, at temperatures 108 K, corresponding to an energy interval where effective 140–230 keV. In this regime, astrophysical S(E)-factor dominated by −3 keV sub-threshold resonance due 6.356 MeV level 17O, giving rise a steep increase S-factor. Its contribution still controversial as...
Slow neutron captures at A$\gtrsim$ 85 are mainly guaranteed by the reaction 13C($\alpha$,n)16O in AGB stars, requiring proton injections from envelope. These were so far assumed to involve a small mass ($\lesssim 10^{-3}$ M$_{\odot}$), but models with rotation suggest that such tiny layers excessive 14N hampers s-processing. Furthermore, s-element abundances Galaxies require 13C-rich substantially extended ($\gtrsim 4 \times M$_{\odot}$). We therefore present new calculations aiming...
Fluorine nucleosynthesis represents one of the most intriguing open questions in nuclear astrophysics. It has triggered new measurements which may modify presently accepted paradigm fluorine production and establish as an accurate probe inner layers asymptotic giant branch (AGB) stars. Both direct indirect have attempted to improve recommended extrapolation astrophysical energies, showing no resonances. In this work, we will demonstrate that interplay between techniques suitable approach...
The (13)C(α,n)(16)O reaction is the neutron source for main component of s-process, responsible production most nuclei in mass range 90</~A</~204. It active inside helium-burning shell asymptotic giant branch stars, at temperatures </~10(8) K, corresponding to an energy interval where effective from 140 230 keV. In this region, astrophysical S(E)-factor dominated by -3 keV subthreshold resonance due 6.356 MeV level (17)O, giving rise a steep increase S(E)-factor. Notwithstanding that it...
The detection of the neutrinos produced in p−p chain and CNO cycle can be used to test Standard Solar Model. 3He(α,γ)7Be reaction is first 2nd 3rd branch chain, therefore, uncertainty its cross section sensitively influences prediction 7Be 8B neutrino fluxes. Despite importance large number experimental theoretical works devoted this reaction, knowledge on at energies characterizing core Sun (15 keV - 30 keV) limited further efforts are needed reach desired (≈ 3%) accuracy. precise external...
Abstract The cosmological lithium problem (CLP) stems from the outstanding discrepancy between theoretical predictions and astronomical observations of primordial abundances. For radiogenic production 7 Li, Be plays a pivotal role in Big Bang nucleosynthesis (BBN). Nevertheless, data for neutron-induced destruction processes were still sparse, especially lacked information on contributions transitions to Li excited states. In this work, we have determined <mml:math...
The $^{13}{\rm C}(\alpha,n)^{16}{\rm O}$ reaction is considered to be the main neutron source responsible for production of heavy nuclides (from ${\rm Sr}$ Bi}$) through slow $n$-capture nucleosynthesis ($s$-process) at low temperatures during asymptotic giant branch (AGB) phase mass stars ($\lesssim 3-4\;{\rm M}_{\odot}$, or LMSs). In recent years, several direct and indirect measurements have been carried out determine cross section energies astrophysical interest (around $190\pm40\;{\rm...
Abstract Recent improvements in stellar models for intermediate-mass stars and massive (MSs) are recalled, together with their expectations the synthesis of radioactive nuclei lifetimes τ ≲ 25 Myr, order to re-examine origins now extinct radioactivities that were alive solar nebula. The Galactic inheritance broadly explains most them, especially if r -process produced by neutron star merging, according recent models. Instead, 26 Al, 41 Ca, 135 Cs, possibly 60 Fe require nucleosynthetic...
Abstract The main source of 19 F in the universe has not yet been clearly identified and this issue represents one unanswered questions stellar modeling. This lack knowledge can be due to F( α , p) 22 Ne reaction cross-section that proven difficult at low energies: direct measurements stop only about ∼660 keV, leaving roughly half astrophysical relevant energy region (from 200 keV 1.1 MeV) explored by R-matrix calculations. In work, we applied Trojan Horse Method quasi-free three-body 6 Li(...
Background: The $^{6}\mathrm{Li}(p,\ensuremath{\gamma})^{7}\mathrm{Be}$ cross section influences a variety of astrophysical scenarios, including big-bang and stellar nucleosynthesis. In recent years, conflicting results direct measurements have been published, reporting contradictory low-energy trends.Purpose: To shed light on the contradiction between existing data sets, reaction was studied using asymptotic normalization coefficient (ANC) technique which up-to-now never used for this...
The 22Ne(α,γ)26Mg and 22Ne(α,n)25Mg reactions play an important role in astrophysics because they have significant influence on the neutron flux during weak branch of s-process. We constrain astrophysical rates for these by measuring partial α-widths resonances 26Mg located Gamow window Ne22+α capture. These were populated using 22Ne(6Li,d)26Mg 22Ne(7Li,t)26Mg at energies near Coulomb barrier. At low α-transfer favor population spin states extracted observed exhibit only minor dependence...
We present here the application of a model for mass circulation mechanism in between H-burning shell and base convective envelope low AGB stars, aimed at studying isotopic composition those presolar grains showing most extreme levels 18O depletion high concentration 26Mg from decay 26Al. The mixing scheme we is based on previously suggested magnetic-buoyancy process, already shown to account adequately formation main neutron source slow captures stars. find that this scenario also capable...
Low mass Asymptotic Giant Branch stars are among the most important polluters of interstellar medium. In their interiors, main component (A>90) slow neutron capture process (the s-process) is synthesized, source being 13C(alpha,n)16O reaction. this paper we review its current experimental status discussing possible future synergies between some experiments currently focused on determination rate. Moreover, in order to determine level precision needed fully characterize reaction, present a...
We study the effects of neutron captures in AGB stars on "Fe-group" elements, with an emphasis Cr, Fe, and Ni. These elements show anomalies 54Cr, 58Fe, 64Ni solar system materials, which are commonly attributed to supernovae (SNe). However, as large fractions interstellar medium (ISM) were reprocessed stars, these reprocessed, too. calculate such reprocessing Ni through 1.5 3 models, adopting 1/3 metallicities. All cases produce excesses 64Ni, while other isotopes little altered; hence,...
Abstract The Mineo pallasite is characterized here for the first time. only 42 g still available worldwide part of collection Department Physics and Geology, University Perugia. A multianalytical approach was used, joining field‐emission scanning electron microscopy, Raman analysis, X‐ray powder diffraction, electron‐probe microanalysis, laser ablation inductively coupled plasma mass spectrometry. Results highlighted that (1) belongs to Main Group pallasites; (2) silicate component...
Abstract Asymptotic Giant Branch (AGB) stars have been proven to be sites of F production through spectroscopy observations by several authors, but it is not clear whether these might account for the total fluorine abundance Galaxy. Recently two main channels 19 destruction in AGB stars, namely F(α,p) 22 Ne and F(p,α) 16 O reactions, studied via Trojan Horse Method energy range interest astrophysics. In both cases experimental results shown presence resonant structures below 500 keV, hinting...
Asymptotic Giant Branch (AGB) stars are among the most important astrophysical sites influencing nucleosynthesis and chemical abundances in Universe. From a pure nuclear point of view, several processes take part during this peculiar stage stellar evolution thus requiring detailed experimental cross section measurements. Here, we report on recent results achieved via application Trojan Horse Method (THM) Normalization Coefficient (ANC) indirect techniques, discussing details procedure...
The Trojan Horse Method (THM) has been applied extensively for the last 25 years to measure nuclear reaction cross sections of interest astrophysics. Although it mainly charged particle-induced reactions, recently found have also a relevant role neutron-induced reactions. Here, some advantages THM will be discussed and preliminary results cosmological 7Be(n,α)4He section measurement are discussed.
The cosmological 7Li problem has been one of the big issues left in standard Big-Bang nucleosynthesis (BBN) model. In order to determine radiogenic abundance by BBN, it is important know production and destruction rate 7Be rather than itself. We performed indirect measurements relevant neutron-induced reactions 7Be(n, p)7Li α)4He simultaneously Trojan Horse Method (THM) via three-body 7Be(d,7Lip)1H 7Be(d, αα)1H. A radioactive-isotope (RI) beam at 3.16 MeV/u was produced...