Nuclear Astrophysics Research Papers - Academia.edu (original) (raw)

We present the details of the construction and commissioning of the Texas–Edinburgh–Catania Silicon Array (TECSA). TECSA is composed of up to 16 Micron Semiconductor Ltd. type-YY1 silicon strip detectors and associated electronics, which... more

We present the details of the construction and commissioning of the Texas–Edinburgh–Catania Silicon Array (TECSA). TECSA is composed of up to 16 Micron Semiconductor Ltd. type-YY1 silicon strip detectors and associated electronics, which is designed for use in studies of nuclear astrophysics and nuclear structure with rare isotope beams. TECSA was assembled at the Texas A&M University, Cyclotron Institute and will be housed there for the next few years. The array was commissioned in a recent experiment where the d(14C,p)15C reaction at 11.7 MeV/u was measured in inverse kinematics.
The results of the measurement and a discussion of the future use of this array are presented.

The golden ring to which most physicists aspire is a unified field theory that incorporates all of modern and classical physics. Some scientists and others call this a TOE or ‘theory of everything’, but it is no more than false hubris to... more

The golden ring to which most physicists aspire is a unified field theory that incorporates all of modern and classical physics. Some scientists and others call this a TOE or ‘theory of everything’, but it is no more than false hubris to believe that humans could possibly know and explain everything about the universe at this time. Einstein chased this goal for the last three decades of his life, basing his theoretical research on his general theory of relativity. Meanwhile, the vast majority of scientists supporting the other major accomplishment of the Second Scientific Revolution were investing all of their time and efforts to advancing the quantum theory and their quest has been extremely successful. They originally had no interest in a unified field theory. After Einstein died in 1955, his efforts were all but abandoned because of his philosophical stance against the prevalent Copenhagen Interpretation of quantum theory even though he had been one of quantum theory’s founders. During the 1970s the tables started to turn and quantum theorists became interested in unifying physics, although not from the foundational principles of relativity theory. They claimed that quantum theory was more fundamental than relativity so they began the same quest from a totally different direction despite their claims to be continuing Einstein’s quest. Throughout the development of the ensuing standard quantum model, superstring theory and many other theoretical schemes, quantum theorists have remained resolute in their conviction that the quantum and relativity are mutually incompatible so the quantum must completely do away with and replace relativity once and for all. However, the quantum theory and relativity are not actually incompatible and, in fact, say the some of the same things about the nature of physical reality. When the similarities are fully defined and studied and the basic assumptions behind each of the theories are altered to reflect the similarities instead of the incompatibilities, only then can the point of their compatibility be determined and act as a unifying principle resulting in a completed unified field theory of the type that Einstein once sought. The development of this physical model of reality is not without irony. Not only is the quantum theory incomplete as Einstein argued in EPR, but Einstein’s general relativity is also seriously incomplete and true unification cannot be rendered complete at any level of reality until all the theoretical models being unified are themselves complete.

The Extreme Light Infrastructure-Nuclear Physics (ELI-NP) facility, under construction in Magurele near Bucharest in Romania, will provide highintensity and high-resolution gamma ray beams that can be used to address hotly debated... more

The Extreme Light Infrastructure-Nuclear Physics (ELI-NP) facility,
under construction in Magurele near Bucharest in Romania, will provide highintensity and high-resolution gamma ray beams that can be used to address hotly debated problems in nuclear astrophysics. For this purpose, a silicon strip detector array (named ELISSA) will be realized in a common effort by ELI-NP and Laboratori Nazionali del Sud (INFN-LNS), in order to measure excitation functions and angular distributions over a wide energy and angular range. An experimental campaign is ongoing in order to test the feasibility of the future study at ELI-NP. With this aim, an experiment has been approved at INFN-LNS in order to measure the 19F(p,απ)16O reaction at astrophysical energies using a prototype of the ELISSA array. Moreover, an exploratory experiment to measure the 7Li(γ, 3H)4He reaction has been performed at High Intensity Gamma Source (HIγS). The good preliminary results of our tests and simulations allows us to conclude that the ELISSA detector will be very suitable for nuclear astrophysics experiments with the upcoming gamma ray beam at the ELI-NP facility.

1. The Main Hypothesis: The Matter Is Created From The Light 2. The produced matter is created in motion, that means the solar planets are created in motions (regardless the motion reason) 3. The solar group are a group of motions... more

1. The Main Hypothesis: The Matter Is Created From The Light
2. The produced matter is created in motion, that means the solar planets are created in motions (regardless the motion reason)
3. The solar group are a group of motions conveyors, So the motions of all solar planets are depended on each other
4. The solar group motions aim to create a difference in motion velocity = C between 2 points in the group.
5. i.e. The Solar Planets work as gears or conveyors group, transfer the motion from point to another point, aiming to create a difference in motion velocity = C velocity. And that's happening where the solar group motions create a difference in velocities between the Earth and Sun motions = C velocity (for that reason the sun is our source of light)
6. The solar group is A Dipole System has 2 heads (the sun and the Earth)
7. The light Production by the planets motions (i.e. by transferring of the mechanical waves into light waves), the original source of light beams energy, from which the solar planets were created, will be conserved.
8. Because there's a difference in velocity = C between 2 points in the solar group (the sun and the Earth), we may conclude easily that, there's more than one frame in the solar group.
9. To create a difference of velocity = C, all solar planets should revolve around the dipole line (The Sun-Earth Line) in the same direction, enabling the velocities addition process to gather all motions in the same point…
10. The Produced Solar Planets should have relationships between their Geometrical structures (if they were created from the light), so the planets are not created independent but related to each other geometrically.

This paper provides an explanation for The Earth Moon Puzzles Let's remember them here again: 1. Earth Moon Distance at Perigee point =363000 km = Solar Outer Planets Diameters Total (error 1%) 2. Earth Moon Distance at Apogee point... more

This paper provides an explanation for The Earth Moon Puzzles Let's remember them here again: 1. Earth Moon Distance at Perigee point =363000 km = Solar Outer Planets Diameters Total (error 1%) 2. Earth Moon Distance at Apogee point =406000 km = Solar Planets Diameters Total 3. The Distance between Perigee and Apogee = 40000km = Inner Solar Planets Diameters Total = Earth Circumference. 4. Saturn Circumference = Earth Moon Distance at total solar eclipse radius (377000 km) 5. Earth daily motion = The moon orbit circumference at apogee radius (406000 km) Why these relationships are found? Because all these distances are originated from the same source, from which all solar planets diameters are created also If all these elements (the diameters and distances) are created from the same source that will support the main concept of my research which is: "The Matter and Distance Are Created Together From the Same Energy That means The Matter is Energy (E=mc 2) The distance is Energy (my hypothesis) That means the Matter and Energy are created from the same Energy which causes the solar group general harmony Please review the planet diameter and orbital distance relationship (d=r*109 2) Mars Immigration Proves (Revised)

We calculate the present expansion of our Universe endowed with relict colored objects - quarks and gluons - that survived hadronization either as isolated islands of quark-gluon "nuggets", or spread uniformly in the Universe. In the... more

We calculate the present expansion of our Universe endowed with relict colored objects - quarks and gluons - that survived hadronization either as isolated islands of quark-gluon "nuggets", or spread uniformly in the Universe. In the first scenario, the QNs can play the role of dark matter. In the second scenario, we demonstrate that uniform colored objects can play the role of dark energy providing the late-time accelerating expansion of the Universe.

Photodisintegration reaction rates involving charged particles are of relevance to the p-process nucleosynthesis that aims at explaining the production of the stable neutron-deficient nuclides heavier than iron. In this study, the cross... more

Photodisintegration reaction rates involving charged particles are of relevance to the p-process nucleosynthesis that aims at explaining the production of the stable neutron-deficient nuclides heavier than iron. In this study, the cross sections and astrophysical rates of (g,p) and (g,a) reactions for about 3000 target nuclei with 10<Z<100 ranging from stable to proton dripline nuclei are computed. To study the sensitivity of the calculations to the optical model potentials (OMPs), both the phenomenological Woods-Saxon and the microscopic folding OMPs are taken into account. The systematic comparisons show that the reaction rates, especially for the (g,a) reaction, are dramatically influenced by the OMPs. Thus the better determination of the OMP is crucial to reduce the uncertainties of the photodisintegration reaction rates involving charged particles. Meanwhile, a gamma-beam facility at ELI-NP is being developed, which will open new opportunities to experimentally study the photodisintegration reactions of astrophysics interest. Considering both the important reactions identified by the nucleosynthesis studies and the purpose of complementing the experimental results for the reactions involving p-nuclei, the measurements of six (g,p) and eight (g,a) reactions based on the gamma-beam facility at ELI-NP and the ELISSA detector for the charged particles detection are proposed, and the GEANT4 simulations are correspondingly performed. The minimum required energies of the gamma-beam to measure these reactions are estimated. It is shown that the direct measurements of these photonuclear reactions within the Gamow windows at T_9=2.5 for p-process are fairly feasible and promising at ELI-NP. The expected experimental results will be used to constrain the OMPs of the charged particles, which can eventually reduce the uncertainties of the reaction rates for the p-process nucleosynthesis.

Present and future gamma-beam facilities represent a great opportunity to validate and evaluate the cross-sections of many photonuclear reactions at near-threshold energies. Monte Carlo (MC) simulations are very important to evaluate the... more

Present and future gamma-beam facilities represent a great opportunity to validate and evaluate the cross-sections of many photonuclear reactions at near-threshold energies. Monte Carlo (MC) simulations are very important to evaluate the reaction rates and to maximize the detection efficiency but, unfortunately, they can be very cpu-time-consuming and in some cases very hard to reproduce, especially when exploring near-threshold cross-section. We developed a software that makes use of the validated tracking GEANT4 libraries and the n-body event generator of ROOT in order to provide a fast, realiable and complete MC tool to be used for nuclear physics experiments. This tool is indeed intended to be used for photonuclear reactions at γ-beam facilities with ELISSA (ELI Silicon Strip Array), a new detector array under development at the Extreme Light Infrastructure-Nuclear Physics (ELI-NP). We discuss the results of MC simulations performed to evaluate the effects of the electromagnetic induced background, of the straggling due to the target thickness and of the resolution of the silicon detectors.

A brief presentation about Stellar Nucleosynthesis on Nuclear Physics classes at FURG.

In stars, four hydrogen nuclei are converted into a helium nucleus in two competing nuclear fusion processes, namely the proton-proton chain (p-p chain) and the carbon-nitrogen-oxygen (CNO) cycle. For temperatures above 20 million kelvin,... more

In stars, four hydrogen nuclei are converted into a helium nucleus in two competing nuclear fusion processes, namely the proton-proton chain (p-p chain) and the carbon-nitrogen-oxygen (CNO) cycle. For temperatures above 20 million kelvin, the CNO cycle dominates energy production, and its rate is determined by the slowest process, the 14N(p,γ)15O radiative capture reaction. This reaction proceeds through direct and resonant capture into the ground state and several excited states in 15O. High energy data for capture into each of these states can be extrapolated to stellar energies using an R-matrix fit. The results from several recent extrapolation studies are discussed. A new experiment at the LUNA (Laboratory for Underground Nuclear Astrophysics) 400kV accelerator in Italy's Gran Sasso laboratory measures the total cross section of the 14N(p,γ)15O reaction with a windowless gas target and a 4π BGO summing detector, down to center of mass energies as low as 70keV. After reviewing the characteristics of the LUNA facility, the main features of this experiment are discussed, as well as astrophysical scenarios where cross section data in the energy range covered have a direct impact, without any extrapolation.

An escape-suppressed, composite high-purity germanium detector of the Clover type has been installed at the Laboratory for Underground Nuclear Astrophysics (LUNA) facility, deep underground in the Gran Sasso Laboratory, Italy. The... more

An escape-suppressed, composite high-purity germanium detector of the Clover type has been installed at the Laboratory for Underground Nuclear Astrophysics (LUNA) facility, deep underground in the Gran Sasso Laboratory, Italy. The laboratory gamma-ray background of the Clover detector has been studied underground at LUNA and, for comparison, also in an overground laboratory. Spectra have been recorded both for the single segments and for the virtual detector formed by online addition of all four segments. The effect of the escape-suppression shield has been studied as well. Despite their generally higher intrinsic background, escape-suppressed detectors are found to be well suited for underground nuclear astrophysics studies. As an example for the advantage of using a composite detector deep underground, the weak ground state branching of the Ep = 223 keV resonance in the 24Mg(p,gamma)25Al reaction is determined with improved precision.

Abstract—The isotopic anomalies of some extinct radionuclides testify to the outburst of a nearby supernova just before the collapse of the protosolar nebula, and to the fact that the supernova was Sn Ia, i.e. the carbon-detonation... more

Abstract—The isotopic anomalies of some extinct radionuclides testify to the outburst of a nearby
supernova just before the collapse of the protosolar nebula, and to the fact that the supernova was Sn Ia, i.e.
the carbon-detonation supernova. A key role of spallation reactions in the formation of isotopic anomalies
in the primordial matter of the Solar System is revealed. It is conditioned by the diffusive acceleration of
particles in the explosive shock waves, which leads to the amplification of rigidity of the energy spectrum of
particles and its enrichment with heavier ions. The quantitative calculations of such isotopic anomalies of
many elements are presented. It is well-grounded that the anomalous Xe-HL in meteoritic nanodiamonds
was formed simultaneously with nanodiamonds themselves during the shock wave propagation at the Sn Ia
explosion. The possible effects of shock wave fractionation of noble gases in the atmosphere of planets are
considered. The origin of light elements Li, Be and B in spallation reactions, predicted by Fowler in the
middle of the last century, is argued. All the investigated isotopic anomalies give the evidence for the
extremely high magneto- hydrodynamics (MHD) сonditions at the initial stage of free expansion of the
explosive shock wave from Sn Ia, which can be essential in solution of the problem of origin of cosmic rays.
The specific iron-enriched matter of Sn Ia and its MHD-separation in turbulent processes must be taking
into account in the models of origin of the Solar System.

The work reported in this dissertation concern the study of kinetics, cycles and quantum mechanic processes of nuclear reactions involved in massive stars together with explosive nucleosynthesis phenomena having a key role in supernovae... more

The work reported in this dissertation concern the study of kinetics, cycles and quantum mechanic processes of nuclear reactions involved in massive stars together with explosive nucleosynthesis phenomena having a key role in supernovae explosion. Four main fields are explored: physics of nuclear reaction, hydrogen burning, CNO cycles and explosive supernovae phenomena. The first chapter provide an overview of the background of the nuclear physics and of the potential approaches to the field as quantum mechanic aspects, cross section and Maxwell-Boltzmann distribution. The next chapter describe the hydrogen burning processes for stars with low mass (our sun), the CNO and hot CNO cycles involved for higher mass stars and other cycles as sodium and magnesium. The third chapter review the helium burning process involved in Red Giants as result of the exhausted hydrogen fuel. A short overview of other helium processes is briefly discussed. The fourth chapter provide a summary of the accepted model of explosive burning process involved in supernovae explosion. Explosive nucleosynthesis together with heavy elements as silicon burning processes are also described.

The work of this dissertation concerns the analysis of the physical properties of 27 Stripped Envelope Supernovae (SE-SNe) using photometric and spectroscopic methods. The first chapter provides an overview of the SE-SNe key features as... more

The work of this dissertation concerns the analysis of the physical properties of 27 Stripped Envelope Supernovae (SE-SNe) using photometric and spectroscopic methods. The first chapter provides an overview of the SE-SNe key features as type classification, light curve properties, spectra profiles, and the explosion mechanisms, including a brief discussion of the possible progenitor stars involved. The second chapter describes and compares four analytical models to compute nickel mass (𝑀𝑁𝑖) and mass ejecta (𝑀𝑒𝑗) highlighting discrepancies of the Khatami’s model between the SNe light curve intensity and velocity rate values. Bolometric light curves for 27 SESNe are computed and key physical properties as nickel mass (𝑀𝑁𝑖) values are estimated and discussed. Spectra analysis including the equivalent width (𝐸𝑊) feature of the Hα and He I lines are briefly discussed, analysing the P-Cygni profile at 6200Ả of the Balmer line. Furthermore, other SE-SNe spectra features as mass ejecta (𝑀𝑒𝑗 ) are calculated analysing the H and He lines strengths and the velocity rate values. Tomographic maps of the nickel mass vs mass ejecta are also included discussing the possible progenitor star origins. The third chapter gives a brief overview of the results obtained and future work. Appendices are also included containing full details of the bolometric light curves, nickel mass (𝑀𝑁𝑖), photospheric velocities (𝑣𝑝ℎ) and the mass ejecta (𝑀𝑒𝑗) calculated values. Uncertainties and error analysis are briefly discussed.

The interior of neutron stars consists of the densest, although relatively cold, matter known in the universe. Here, baryon number densities might reach values close to ten times the nuclear saturation density. These suggest that the... more

The interior of neutron stars consists of the densest, although relatively cold, matter known in the universe. Here, baryon number densities might reach values close to ten times the nuclear saturation density. These suggest that the constituents of neutron star cores not only consist of nucleons, but also of more exotic baryons like hyperons or a phase of deconfined quarks. We discuss the consequences of such exotic particles on the gross properties and phenomenology of neutron stars. In addition, we determine the general phase structure of dense and also hot matter in the chiral parity-doublet model and confront model results with the recent constraints derived from the neutron star merger observation.

Present and future gamma-beam facilities represent a great opportunity to validate and evaluate the cross-sections of many photonuclear reactions at near-threshold energies, whose data mostly come from theoretical calculations. We... more

Present and future gamma-beam facilities represent a great opportunity to validate and evaluate the cross-sections of many photonuclear reactions at near-threshold energies, whose data mostly come from theoretical calculations. We developed a Monte Carlo (MC) software that makes use of the validated tracking Geant4 libraries and the n-body event generator of ROOT libraries in order to provide a fast, realiable and complete MC tool to be used for nuclear physics experiments, with a particular focus on photo-nuclear processes. We discuss the results of the MC simulations performed in order to evaluate the effects of the electromagnetic background, the straggling of the emitted particles due to the target thickness and the resolution of the silicon detectors. Finally we present the preliminary results on some nuclear reactions involved in the p-process, which will be studied with ELISSA and the GBS at ELI-NP.

The accurate knowledge of the ¹Au(n,) reaction cross section is of great importance, since this reaction if often used as a reference in capture cross section measurements relevant to Nuclear Astrophysics, as well as for neutron flux... more

The accurate knowledge of the ¹Au(n,) reaction cross section is of great importance, since this reaction if often used as a reference in capture cross section measurements relevant to Nuclear Astrophysics, as well as for neutron flux determination in nuclear power reactors. With the aim of improving the accuracy of the neutron capture cross section on ¹Au, extensive measurements were

Neutron star mergers are among the most promising sources of gravitational waves for advanced ground-based detectors. These mergers are also expected to power bright electromagnetic signals, in the form of short gamma-ray bursts,... more

Neutron star mergers are among the most promising sources of gravitational waves for advanced ground-based detectors. These mergers are also expected to power bright electromagnetic signals, in the form of short gamma-ray bursts, infrared/optical transients powered by r-process nucleosynthesis in neutron-rich material ejected by the merger, and radio emission from the interaction of that ejecta with the interstellar medium. Simulations of these mergers with fully general relativistic codes are critical to understand the merger and post-merger gravitational wave signals and their neutrinos and electromagnetic counterparts. In this paper, we employ the Spectral Einstein Code (SpEC) to simulate the merger of low-mass neutron star binaries (two 1.2M neutron stars) for a set of three nuclear-theory based, finite temperature equations of state. We show that the frequency peaks of the post-merger gravitational wave signal are in good agreement with predictions obtained from recent simulations using a simpler treatment of gravity. We find, however, that only the fundamental mode of the remnant is excited for long periods of time: emission at the secondary peaks is damped on a millisecond timescale in the simulated binaries. For such low-mass systems, the remnant is a massive neutron star which, depending on the equation of state, is either permanently stable or long-lived (i.e. rapid uniform rotation is sufficient to prevent its collapse). We observe strong excitations of l = 2, m = 2 modes, both in the massive neutron star and in the form of hot, shocked tidal arms in the surrounding accretion torus. We estimate the neutrino emission of the remnant using a neutrino leakage scheme and, in one case, compare these results with a gray two-moment neutrino transport scheme. We confirm the complex geometry of the neutrino emission, also observed in previous simulations with neutrino leakage, and show explicitly the presence of important differences in the neutrino luminosity, disk composition, and outflow properties between the neutrino leakage and transport schemes.

The objective of the R&D project CLAIRE is to prove the principle of a gamma-ray lens for nuclear astrophysics. CLAIRE features a Laue diffraction lens, an actively shielded array of germanium detectors, and a balloon gondola stabilizing... more

The objective of the R&D project CLAIRE is to prove the principle of a gamma-ray lens for nuclear astrophysics. CLAIRE features a Laue diffraction lens, an actively shielded array of germanium detectors, and a balloon gondola stabilizing the gamma-ray lens to a few arcseconds. On June 14 2001, the instrument was flown on a stratospheric balloon by the French Space Agency CNES; the astrophysical target was a Òstandard candleÓ, the Crab nebula. CLAIREÕs first light consists of ~33 diffracted photons from the Crab, corresponding to a 3 σ detection. The performance of the gamma-ray lens during the balloon flight has been confirmed by ground data obtained at a 200 meter long test range. Based on the diffraction efficiencies measured with CLAIRE, the mission concept of a space borne gamma-ray lens is proposed, and its potential for nuclear astrophysics is outlined.