scholarly journals The LUNA experiment: past and future

2018 ◽  
Vol 184 ◽  
pp. 01003
Author(s):  
Carlo Broggini
Keyword(s):  
Cross Sections ◽  
Chemical Elements ◽  
Nuclear Astrophysics ◽  
Hydrogen Burning ◽  
Life And Death ◽  
Reac Tions ◽  
Nuclear Burning ◽  
Deep Underground ◽  
Solar Phase ◽  
Carbon Burning

The essential ingredients of nuclear astrophysics are the thermonuclear reac-tions which shape the life and death of stars and which are responsible for the synthesis of the chemical elements in the Universe. Deep underground in the Gran Sasso Laboratory the cross sections of the key reactions responsible for the hydrogen burning in stars have been measured with two accelerators of 50 and 400 kV voltage right down to the energies of astrophysical interest. In particular, the main results obtained during the 'solar' phase of LUNA are here reviewed and their influence on our understanding of the properties of the neutrino and of the Sun is discussed. Then, the future of LUNA during the next decade is outlined. It will be mainly focused on the study of the nuclear burning stages after hydrogen burning: helium and carbon burning. All this will be accomplished thanks to a new 3.5 MV accelerator able to deliver high current beams of proton, helium and carbon which will start running under Gran Sasso in 2019.

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.

scholarly journals The Study of Key Reactions Shaping the Post-Main Sequence Evolution of Massive Stars in Underground Facilities

2021 ◽  
Vol 7 ◽  
Author(s):  
F. Ferraro ◽  
G. F. Ciani ◽  
A. Boeltzig ◽  
F. Cavanna ◽  
S. Zavatarelli
Keyword(s):  
Cross Sections ◽  
Main Sequence ◽  
Nuclear Reactions ◽  
Nuclear Astrophysics ◽  
Sequence Evolution ◽  
Present Contribution ◽  
Hydrogen Burning ◽  
Ion Accelerator ◽  
Direct Cross ◽  
Carbon Burning

The chemical evolution of the Universe and several phases of stellar life are regulated by minute nuclear reactions. The key point for each of these reactions is the value of cross-sections at the energies at which they take place in stellar environments. Direct cross-section measurements are mainly hampered by the very low counting rate and by cosmic background; nevertheless, they have become possible by combining the best experimental techniques with the cosmic silence of an underground laboratory. In the nineties, the LUNA (Laboratory for Underground Nuclear Astrophysics) collaboration opened the era of underground nuclear astrophysics, installing first a homemade 50 kV and, later on, a second 400 kV accelerator under the Gran Sasso mountain in Italy: in 25 years of experimental activity, important reactions responsible for hydrogen burning could have been studied down to the relevant energies thanks to the high current proton and helium beams provided by the machines. The interest in the next and warmer stages of star evolution (i.e., post-main sequence and helium and carbon burning) drove a new project based on an ion accelerator in the MV range called LUNA-MV, able to deliver proton, helium, and carbon beams. The present contribution is aimed to discuss the state of the art for some selected key processes of post-main sequence stellar phases: 12C(α,γ)16O and 12C+12C are fundamental for helium and carbon burning phases, and 13C(α,n)16O and 22Ne(α,n)25Mg are relevant to the synthesis of heavy elements in AGB stars. The perspectives opened by an underground MV facility will be highlighted.

scholarly journals Nuclear Astrophysics Deep Underground

2018 ◽  
Vol 46 ◽  
pp. 1860003 ◽  
Author(s):  
Rosanna Depalo
Keyword(s):  
Cross Sections ◽  
Nuclear Reactions ◽  
Nuclear Astrophysics ◽  
Cosmic Ray ◽  
Big Bang ◽  
Big Bang Nucleosynthesis ◽  
Present Contribution ◽  
Hydrogen Burning ◽  
The Earth ◽  
Deep Underground

Cross sections of nuclear reactions relevant for astrophysics are crucial ingredients to understand the energy generation inside stars and the synthesis of the elements. At astrophysical energies, nuclear cross sections are often too small to be measured in laboratories on the Earth surface, where the signal would be overwhelmed by the cosmic-ray induced background. LUNA is a unique Nuclear Astrophysics experiment located at Gran Sasso National Laboratories. The extremely low background achieved at LUNA allows to measure nuclear cross sections directly at the energies of astrophysical interest. Over the years, many crucial reactions involved in stellar hydrogen burning as well as Big Bang nucleosynthesis have been measured at LUNA. The present contribution provides an overview on underground Nuclear Astrophysics as well as the latest results and future perspectives of the LUNA experiment.

scholarly journals The Chemical Evolution of the Main Component of the Binary System v Sagitarrii

1998 ◽  
Vol 11 (1) ◽  
pp. 390-390
Author(s):  
V. Leushin ◽  
V. Chuvenkov ◽  
L. Snezhko
Keyword(s):  
Chemical Composition ◽  
Binary System ◽  
Core Mass ◽  
Hydrogen Burning ◽  
Convective Mixing ◽  
Mixing Parameters ◽  
Burning Zone ◽  
Nuclear Burning ◽  
Nitrogen Abundance ◽  
Main Component

A model of internal structure and evolution of the peculiar binary system v Sgr is presented. The model corresponds well to the observed chemical composition of the main component atmosphere (10-4 H, 0.844 He, 0.013 C, 0.042 N by mass). It is supposed that about 5 million years ago the main component passed the stage of hydrogen nuclear burning in the shell over the helium core where the helium-carbon reactions took place. Because of convective mixing, the synthesized carbon diffusing into the hydrogen burning zone was catalyzing the reactions of the CN - cycle. This has resulted in anomalies in the chemical composition, particularly high nitrogen abundance in the layer observed now as the atmosphere of the main component since external layers were thrown off during the evolution. Following the calculated results, the quantitative restrictions of temperature and density in the layers and values of mixing parameters are obtained. It is shown that the best agreement with observations exists if the mass of the matter penetrating from the zone of helium-carbon reactions into the helium layer is 0.25 of the helium-carbon core mass. Moreover, the ratio of mass concentration He/C in this matter should equal 2, and the mass share diffusing into the layer of hydrogen burning should be in the range 0.25 - 0.30 of the layer mass.

scholarly journals Global predictions for astrophysics applications

2020 ◽  
Vol 13 ◽  
pp. 18
Author(s):  
P. Demetriou
Keyword(s):  
Nuclear Reaction ◽  
Cross Sections ◽  
Nuclear Reactions ◽  
Nuclear Astrophysics ◽  
Reaction Network ◽  
Reaction Rates ◽  
Reaction Cross ◽  
Hartree Fock ◽  
Microscopic Models ◽  
The Stability

Nuclear reaction rates play a crucial role in nuclear astrophysics. In the last decades there has been an enormous effort to measure reaction cross sections and extensive experimental databases have been compiled as a result. In spite of these efforts, most nuclear reaction network calculations still have to rely on theoretical predic- tions of experimentally unknown rates. In particular, in astrophysics applications such as the s-, r- and p-process nucleosynthesis involving a large number of nuclei and nuclear reactions (thousands). Moreover, most of the ingredients of the cal- culations of reaction rates have to be extrapolated to energy and/or mass regions that cannot be explored experimentally. For this reason it is important to develop global microscopic or semi-microscopic models of nuclear properties that give an accurate description of existing data and are reliable for predictions far away from the stability line. The need for more microscopic input parameters has led to new devel- opments within the Hartree-Fock-Bogoliubov method, some of which are presented in this paper.

scholarly journals Neutron capture data for unstable nuclei – Astrophysical quests and experimental challenges

2019 ◽  
Vol 23 ◽  
pp. 1
Author(s):  
F. Käppeler
Keyword(s):  
Cross Sections ◽  
Reaction Path ◽  
Chemical Elements ◽  
Neutron Sources ◽  
Unstable Nuclei ◽  
Quantitative Studies ◽  
Branching Points ◽  
Supernova Explosions ◽  
R Process ◽  
Pulsed Neutron

The abundances of the chemical elements heavier than iron can be attributed in about equal parts to the r and s processes, which are taking place in supernova explosions and during the He and C burning phases of stellar evolution, respectively. So far, quantitative studies of the r-process are out of reach, because it involves reactions on extremely short-lived neutron-rich nuclei. On the contrary, the situation for the s-process is far advanced, thanks to a comprehensive database of experimental (n,γ) cross sections for most isotopes along the reaction path from 12C to the Pb/Bi region. For the stable isotopes last gaps in the data are presently closed, but further studies are clearly needed to reach the required accuracy and to resolve remaining discrepancies. The quest for cross sections of unstable isotopes remains a persisting challenge though. In particular, nuclei which act as branching points are of prime interest, because they provide key information on the deep stellar interior. While the activation method is limited to a few exceptional branch-point nuclei, successful measurements via the time-of- flight technique are depending on intense pulsed neutron sources and elaborate methods for sample production. Current developments in Europe are providing promising perspectives in both areas.

scholarly journals Unscreened cross-sections for nuclear astrophysics via the Trojan Horse Method

2014 ◽  
Vol 569 ◽  
pp. 012018
Author(s):  
A Tumino ◽  
C Spitaleri ◽  
M La Cognata ◽  
L Lamia ◽  
R G Pizzone ◽  
...  
Keyword(s):  
Cross Sections ◽  
Nuclear Astrophysics ◽  
Trojan Horse ◽  
Trojan Horse Method

Nuclear Astrophysics Experiments for Explosive Hydrogen Burning

2016 ◽  
Vol 66 (12) ◽  
pp. 1511-1517
Author(s):  
Insik HAHN* ◽  
Aram KIM
Keyword(s):  
Nuclear Astrophysics ◽  
Hydrogen Burning

CNO hydrogen burning studied deep underground

2010 ◽  
pp. 161-170
Author(s):  
D. Bemmerer ◽  
F. Confortola ◽  
A. Lemut ◽  
R. Bonetti ◽  
C. Broggini ◽  
...  
Keyword(s):  
Hydrogen Burning ◽  
Deep Underground

Analysis of the hair coat of domestic cats with special focus on histological structure

2017 ◽  
Vol 13 (1) ◽  
pp. 47-58
Author(s):  
Anna Wyrostek ◽  
Katarzyna Roman ◽  
Katarzyna Czyż ◽  
Marzena Janczak ◽  
Bożena Patkowska-Sokoła
Keyword(s):  
Cross Sections ◽  
Chemical Elements ◽  
Coat Colour ◽  
Histological Structure ◽  
Special Focus ◽  
Domestic Cats ◽  
Hair Coat ◽  
Research Material ◽  
Hair Type ◽  
Axis Length

The aim of the study was to characterize the hair coat of domestic cats. The research material consisted of hairs of different fractions collected in winter from female cats with a uniform hair coat colour: white,cream, red, brown and black. The hairs were divided into individual fractions, i.e. underhair, bristle hair and guard hair, and the following characteristics were evaluated: thickness, length, long and short axis length, stress at break and elongation. SEM (scanning electron microscope) images of all types of hair were taken and used to characterize each hair type and to calculate the number of scales per mm of hair length. The content of ions of various chemical elements was determined as well. Underhairs, which accounted for the largest percentage in the coat, were the thinnest and shortest, and had the most regular and distinct scale pattern. Guard hairs were the least numerous, but were the longest and thickest of all hairs examined. Both guard and bristle hairs had irregular scales with jagged edges. The cross-sections of these hairs revealed the presence of all the layers, i.e. the cuticle, cortex and medulla. In the underhair fraction the medulla was observed only in red cats. In all hairs the share of carbon, oxygen and sulphur ions was largest; these are the main omponents of hair protein, i.e. keratin.

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