scholarly journals APPLICATION OF TWO-CLUSTER MICROSCOPIC MODEL TO STUDY PROCESSES ASSOCIATED WITH THE COSMOLOGICAL LITHIUM PROBLEM

2020 ◽  
Vol 72 (4) ◽  
pp. 105-111
Author(s):  
N.K. Kalzhigitov ◽  
◽  
V.О. Kurmangaliyeva ◽  
N.K. Amanzhol ◽  
B.K. Turarov ◽  
...  
Keyword(s):  
Nuclear Physics ◽  
Radiative Capture ◽  
Nuclear Astrophysics ◽  
Group Method ◽  
Calculation Methods ◽  
Resonance States ◽  
Algebraic Version ◽  
The Universe ◽  
Good Agreement ◽  
Exchange Parameters

This paper presents the results of studies of long-lived resonance states of the 6Li nucleus and the radiative capture reaction leading to the synthesis of 6Li. In connection with the importance of the lithium problem for the fields of nuclear physics and nuclear astrophysics, the reactions of primary nucleosynthesis are of great interest for studies and consideration using new calculation methods. Cluster models are a powerful tool for theoretical analysis and solution of this problem. One of these models is the microscopic cluster model, or a method known as the algebraic version of the resonant group method (AVRGM), which will allow us to investigate this problem from a new angle and obtain data on resonance states. For this task, a modified Hasegawa-Nagata potential was chosen, which has its own unique characteristics and exchange parameters. The obtained data were compared with experimental data and it was shown that they showed good agreement, and the applicability of this technique to the description of similar reactions that originate in the first three minutes after the birth of the universe.

ON THE CLUSTER-MODEL DESCRIPTION OF COLLISIONS

2011 ◽  
Vol 20 (04) ◽  
pp. 769-774
Author(s):  
DANIEL BAYE
Keyword(s):  
Cluster Model ◽  
Radiative Capture ◽  
Nuclear Astrophysics ◽  
Model Description ◽  
Group Method ◽  
Final State ◽  
Full Account ◽  
Scattering States ◽  
Quantum Numbers ◽  
Three Body

With simple cluster wave functions describing the colliding nuclei, the resonating-group method allows treating collisions realistically with full account of antisymmetrization and of good quantum numbers. The introduction of generator coordinates leads to a striking simplification by allowing the systematic use of Slater determinants. Reactions involving bound and scattering states simultaneously, such as radiative-capture reactions in nuclear astrophysics, are a particularly rich field of applications. In recent years, the microscopic cluster model has evolved to the study of three-body scattering which appears as a final state in a number of processes. The challenge is now to extend microscopic descriptions of collisions to ab initio calculations with realistic forces.

scholarly journals THE RADIATIVE NEUTRON CAPTURE ON 2H, 6Li, 7Li, 12C AND 13C AT ASTROPHYSICAL ENERGIES

2013 ◽  
Vol 22 (05) ◽  
pp. 1350028 ◽  
Author(s):  
SERGEY DUBOVICHENKO ◽  
ALBERT DZHAZAIROV-KAKHRAMANOV ◽  
NATALIA BURKOVA
Keyword(s):  
Neutron Capture ◽  
Nuclear Physics ◽  
Nuclear Reactions ◽  
Nuclear Astrophysics ◽  
General Description ◽  
Primordial Nucleosynthesis ◽  
Atomic Nuclei ◽  
Radiative Neutron ◽  
Radiative Neutron Capture ◽  
The Universe

The continued interest in the study of radiative neutron capture on atomic nuclei is due, on the one hand, to the important role played by this process in the analysis of many fundamental properties of nuclei and nuclear reactions, and, on the other hand, to the wide use of the capture cross-section data in the various applications of nuclear physics and nuclear astrophysics, and, also, to the importance of the analysis of primordial nucleosynthesis in the Universe. This paper is devoted to the description of results for the processes of the radiative neutron capture on certain light atomic nuclei at thermal and astrophysical energies. The consideration of these processes is done within the framework of the potential cluster model (PCM), general description of which was given earlier. The methods of usage of the results obtained, based on the phase shift analysis intercluster potentials, are demonstrated in calculations of the radiative capture characteristics. The considered capture reactions are not part of stellar thermonuclear cycles, but involve in the basic reaction chain of primordial nucleosynthesis in the course of the Universe formation.

Origin and status of LUNA at Gran Sasso

2014 ◽  
Vol 29 (34) ◽  
pp. 1430038
Author(s):  
Carlo Broggini ◽  
Keyword(s):  
Nuclear Physics ◽  
Nuclear Reactions ◽  
Chemical Elements ◽  
Nuclear Astrophysics ◽  
Hydrogen Burning ◽  
Proton Proton ◽  
Oxygen Cycle ◽  
Comprehensive Picture ◽  
Deep Underground ◽  
The Universe

The ultimate goal of nuclear astrophysics, the union of nuclear physics and astronomy, is to provide a comprehensive picture of the nuclear reactions which power the stars and, in doing so, synthesize the chemical elements. Deep underground in the Gran Sasso Laboratory the key reactions of the proton–proton chain and of the carbon–nitrogen–oxygen cycle have been studied down to the energies of astrophysical interest. The main results obtained in the past 20 years are reviewed and their influence on our understanding of the properties of the neutrino, the Sun, and the Universe itself is discussed. Finally, future developments of underground nuclear astrophysics beyond the study of hydrogen burning are outlined.

Nuclear astrophysics: nucleosynthesis in the Universe

2012 ◽  
Vol 11 (4) ◽  
pp. 243-250 ◽  
Author(s):  
Alinka Lépine-Szily ◽  
Pierre Descouvemont
Keyword(s):  
Energy Range ◽  
Cross Sections ◽  
Nuclear Physics ◽  
Nuclear Astrophysics ◽  
Reaction Rates ◽  
Reaction Cross ◽  
Point Of View ◽  
Definition Of ◽  
The Universe ◽  
Reaction Cross Sections

AbstractNuclear astrophysics is a relatively young science; it is about half a century old. It is a multidisciplinary subject, since it combines nuclear physics with astrophysics and observations in astronomy. It also addresses fundamental issues in astrobiology through the formation of elements, in particular those required for a carbon-based life. In this paper, a rapid overview of nucleosynthesis is given, mainly from the point of view of nuclear physics. A short historical introduction is followed by the definition of the relevant nuclear parameters, such as nuclear reaction cross sections, astrophysical S-factors, the energy range defined by the Gamow peak and reaction rates. The different astrophysical scenarios that are the sites of nucleosynthesis, and different processes, cycles and chains that are responsible for the building of complex nuclei from the elementary hydrogen nuclei are then briefly described.

scholarly journals New theoretical results for radiative 3H(p,γ)4He, 3He(2H,γ)5Li, 4He(2H,γ)6Li, 4He(3H,γ)7Li and 4He(3He,γ)7Be captures at astrophysical energies

2019 ◽  
Vol 28 (03) ◽  
pp. 1930004 ◽  
Author(s):  
Sergey Dubovichenko ◽  
Albert Dzhazairov-Kakhramanov ◽  
Nataliya Burkova
Keyword(s):  
Radiative Capture ◽  
Nuclear Astrophysics ◽  
Big Bang ◽  
Proton Proton ◽  
Capture Reaction ◽  
Primordial Nucleosynthesis ◽  
Proton Fusion ◽  
The Big Bang ◽  
The Universe ◽  
Theoretical Results

We have studied the proton capture reaction [Formula: see text]. It plays a role in the nucleosynthesis of primordial elements in the early Universe leading to the prestellar formation of [Formula: see text] nuclei. All results of our researches and more new data from works show that the contribution of the [Formula: see text] capture reaction into the processes of primordial nucleosynthesis is relatively small. However, it makes sense to consider this process for making the picture complete for the formation of prestellar [Formula: see text] and clearing of mechanisms of this reaction. Furthermore, we have considered the [Formula: see text] reaction in the low energy. This reaction also forms part of the nucleosynthesis chain of the processes occurring in the early stages of formation of stable stars. They are possible candidates for overcoming the well-known problem of the [Formula: see text] gap in the synthesis of light elements in the primordial Universe. Continuing the study, we have considered the radiative capture [Formula: see text] at superlow energies, which has a undeniable interest for nuclear astrophysics, since it takes part in the proton–proton fusion chain, and new experimental data on the astrophysical [Formula: see text]-factors of this process at energies down to 90 and 23[Formula: see text]keV and data on the radiative capture reaction [Formula: see text] down to 50[Formula: see text]keV appeared recently. Moreover, radiative capture reactions [Formula: see text] and [Formula: see text] may have played a certain role in prestellar nucleosynthesis after the Big Bang, when the temperature of the Universe decreased to the value of [Formula: see text].

Observations of the Sun

1997 ◽  
Author(s):  
Douglas V. Hoyt ◽  
Kenneth H. Shatten
Keyword(s):  
Nuclear Physics ◽  
Nuclear Reactions ◽  
Stellar Structure ◽  
Heavy Elements ◽  
Helium Nucleus ◽  
The Sun ◽  
Helium Gas ◽  
A Chain ◽  
The One ◽  
The Universe

Our sun is a typical “second generation,” or G2, star nearly 4.5 billion years old. The sun is composed of 92.1% hydrogen and 7.8% helium gas, as well as 0.1% of such all-important heavy elements as oxygen, carbon, nitrogen, silicon, magnesium, neon, iron, sulfur, and so forth in decreasing amounts (see Appendix 3). The heavy elements are generated from nucleosynthetic processes in stars, novae, and supernovae after the original formation of the Universe. This has led to the popular statement that we are, literally, the “children of the stars” because our bodies are composed of the elements formed inside stars. From astronomical studies of stellar structure, we know that, since its beginnings, the sun’s luminosity has gradually increased by about 30%. This startling conclusion has raised the so-called faint young sun climate problem: if the sun were even a few percent fainter in the past, then Earth could have been covered by ice. In this frozen state, it might not have warmed because the ice would reflect most of the incoming solar radiation back into space. Although volcanic aerosols covering the ice, early oceans moderating the climate, and other theories have been suggested to circumvent the “faint young sun” problem, how Earth escaped the ice catastrophe remains uncertain. How can the sun generate vast amounts of energy for billions of years and still keep shining? Before nuclear physics, scientists believed the sun generated energy by means of slow gravitational collapse. Still, this process would only let the sun shine about 30 million years before its energy was depleted. To shine longer, the sun requires another energy source. We now believe that a chain of nuclear reactions occurs inside the sun, with four hydrogen nuclei fusing into one helium nucleus at the sun’s center. Because the four hydrogen nuclei have more mass than the one helium nucleus, the resulting mass deficit is converted into energy according to Einstein’s famous formula E = mc2. The energy, produced near the sun’s center, creates a central temperature of about 15 million degrees Kelvin (°K).

Astrophysics and Nucleosynthesis

2019 ◽  
Author(s):  
Eric Scerri
Keyword(s):  
Steady State ◽  
Relative Abundance ◽  
Nuclear Physics ◽  
Big Bang ◽  
Atomic Weight ◽  
Considerable Extent ◽  
Cosmological Debate ◽  
State Models ◽  
The Big Bang ◽  
The Universe

Having now examined attempts to explain the nature of the elements and the periodic system in a theoretical manner, it is necessary to backtrack a little in order to pick up a number of important issues not yet addressed. As in the preceding chapters, several contributions from fields outside of chemistry are encountered, and the treatment proceeds historically. So far in this book, the elements have been treated as if they have always existed, fully formed. Nothing has yet been said about how the elements have evolved or about the relative abundance of the isotopes of the elements. These questions form the contents of this chapter. It also emerges that different isotopes show different stabilities, a feature that can be explained to a considerable extent by appeal to theories from nuclear physics. The study of nucleosynthesis, and especially the development of this field, is intimately connected to the development of the field of cosmology as a branch of physical science. In a number of instances, different cosmological theories have been judged according to the degree to which they could explain the observed universal abundances of the various elements. Perhaps the most controversial cosmological debate has been over the rival theories of the big bang and the steady-state models of the universe. The proponents of these theories frequently appealed to relative abundance data, and indeed, the eventual capitulation of the steady-state theorists, or at least some of them, was crucially dependent upon the observed ratio of hydrogen to helium in the universe. Chapters 2, 3, and 6 discussed Prout’s hypothesis, according to which all the elements are essentially made out of hydrogen. Although the hypothesis was initially rejected on the basis of accurate atomic weight determinations, it underwent a revival in the twentieth century. As mentioned in chapter 6, the discoveries of Anton van den Broek, Henry Moseley, and others showed that there is a sense in which all elements are indeed composites of hydrogen.

Studying the Patterns of the Universe

2011 ◽  
Vol 20 (2) ◽  
Author(s):  
T. Sepp ◽  
E. Tempel ◽  
M. Gramann ◽  
P. Nurmi ◽  
M. Haupt
Keyword(s):  
Dark Matter ◽  
Galaxy Cluster ◽  
Analytical Models ◽  
Matter Distribution ◽  
Galaxy Groups ◽  
The Galaxy ◽  
Dark Matter Distribution ◽  
Distribution Studies ◽  
The Universe ◽  
Good Agreement

AbstractThe SDSS galaxy catalog is one of the best databases for galaxy distribution studies. The SDSS DR8 data is used to construct the galaxy cluster catalog. We construct the clusters from the calculated luminosity density field and identify denser regions. Around these peak regions we construct galaxy clusters. Another interesting question in cosmology is how observable galaxy structures are connected to underlying dark matter distribution. To study this we compare the SDSS DR7 galaxy group catalog with galaxy groups obtained from the semi-analytical Millennium N-Body simulation. Specifically, we compare the group richness, virial radius, maximum separation and velocity dispersion distributions and find a relatively good agreement between the mock catalog and observations. This strongly supports the idea that the dark matter distribution and galaxies in the semi-analytical models and observations are very closely linked.

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