scholarly journals The Study of the 6Li(p,γ)7Be Reaction at LUNA

2020 ◽  
Vol 1668 (1) ◽  
pp. 012034
Author(s):  
D. Piatti
Keyword(s):  
Cross Section ◽  
Main Sequence ◽  
Theoretical Calculations ◽  
Nuclear Astrophysics ◽  
Recent Measurement ◽  
Main Sequence Stars ◽  
Primordial Nucleosynthesis ◽  
Direct Measurements ◽  
S Factor ◽  
Low Energies

Abstract The 6Li(p,γ)7Be reaction is mainly involved in two astrophysical scenarios: the primordial nucleosynthesis and 6Li consumption in pre-main and main sequence stars. A recent measurement of 6Li(p,γ)7Be reaction S-factor reported a resonance-like structure at Ecm = 195 keV, which has not been confirmed neither by other direct measurements nor by theoretical calculations. A new experiment was performed at the Laboratory for Underground Nuclear Astrophysics (LUNA). The extremely low background environment allowed to measure the 6Li(p,γ)7Be cross section down to low energies with unprecedented sensitivity leading to clarify the existence of the claimed resonance. Details on the experimental setup and the preliminary results of the ongoing analysis are reported in this work.

scholarly journals The 12C(a,g)16O Cross Section at Low Energies

1991 ◽  
Vol 44 (4) ◽  
pp. 369 ◽  
Author(s):  
FC Barker ◽  
T Kajino
Keyword(s):  
Cross Section ◽  
Ground State ◽  
State Transitions ◽  
Correct Treatment ◽  
R Matrix ◽  
A Value ◽  
S Factor ◽  
Low Energies ◽  
Cascade Transitions ◽  
Matrix Formula

An R-matrix formula for the cross section for radiative capture reactions is developed and applied to fit recently measured 12C(oc,y)160 data, for both ground-state transitions and cascade transitions through the 6�92 and 7 �12 MeV levels. The correct treatment of the channel contributions is significant for the E2 cascade transitions. Consistent fits of the cascade and ground-state data suggest a value of the channel radius larger than those previously used, and consequently a value of the low-energy astrophysical S-factor appreciably larger than that adopted recently.

scholarly journals Underground Nuclear Astrophysics: pushing direct measurements toward the Gamow window

2020 ◽  
Vol 227 ◽  
pp. 01015
Author(s):  
Paolo Prati
Keyword(s):  
Nuclear Reactions ◽  
Nuclear Astrophysics ◽  
Cosmic Ray ◽  
Reaction Rates ◽  
Carbon Ions ◽  
Ongoing Research ◽  
Ion Accelerator ◽  
Direct Measurements ◽  
Low Energies ◽  
Deep Underground

The aim of experimental nuclear astrophysics is to provide information on the nuclear processes involved in astrophysical scenarios at the relevant energy range. However, the measurement of the cross section of nuclear reactions at low energies present formidable difficulties due to the very low reaction rates often overwhelmed by the background. Several approaches have been proposed and exploited to overcome such severe obstacles: in such frame, the idea to install a low energy - high intensity ion accelerator deep underground, to gain high luminosity while reducing the cosmic ray background, brought more than 25 years ago, to the pilot LUNA experiment. LUNA stands for Laboratory for Underground Nuclear Astrophysics: in the cave under the Gran Sasso mountain (in Italy) first a 50 kV and then a 400 kV single-ended accelerator for protons and alphas were deployed and produced plenty of data mainly on reactions of the H-burning phase in stars. Recently, similar facilities have been installed and/or proposed in other underground laboratories in US and China. LUNA as well is going to make a big step forward, with a new machine in the MV range which will be able to provide intense beams of protons, alphas and carbon ions. The rationale of underground nuclear astrophysics will be presented together with the last updates on the ongoing research programs.

scholarly journals Nuclear astrophysics at Gran Sasso Laboratory: the LUNA experiment

2018 ◽  
Vol 178 ◽  
pp. 01007
Author(s):  
Francesca Cavanna
Keyword(s):  
Cross Section ◽  
Direct Measurement ◽  
Experimental Approach ◽  
Nuclear Reactions ◽  
Nuclear Fusion ◽  
Nuclear Astrophysics ◽  
Fusion Reactions ◽  
Primordial Nucleosynthesis ◽  
Future Goals ◽  
Nuclear Fusion Reactions

LUNA is an experimental approach for the study of nuclear fusion reactions based on an underground accelerator laboratory. Aim of the experiment is the direct measurement of the cross section of nuclear reactions relevant for stellar and primordial nucleosynthesis. In the following the latest results and the future goals will be presented.

Analysis of cross section and astrophysical S-factor at low energies

2013 ◽  
Author(s):  
Azni Abdul Aziz ◽  
Hasan Abu Kassim ◽  
Muhammad F. Zamrun
Keyword(s):  
Cross Section ◽  
S Factor ◽  
Low Energies

scholarly journals Nuclear astrophysics studies at NIPNE

2020 ◽  
Vol 227 ◽  
pp. 01016
Author(s):  
Livius Trache
Keyword(s):  
Nuclear Astrophysics ◽  
List Type ◽  
Salt Mine ◽  
Nuclear Engineering ◽  
Radioactive Beams ◽  
Indirect Measurements ◽  
Low Background ◽  
Direct Measurements ◽  
Gamma Coincidence ◽  
Low Energies

I will present results of doing nuclear astrophysics research at the National Institute for Physics and Nuclear Engineering, Bucharest-Magurele in the last 2-3 years. Own Nuclear Astrophysics Group (NAG) is focused on the basic types of experiments: -Direct measurements at low and very low energies with ion or alpha beams from the local 3 MV tandetron accelerator. We concentrate on activation measurements. The use of the ultra-low background laboratory in a salt mine at Slanic-Prahova, about 120 km away and of a beta-gamma coincidence unit at home is providing competitive sensitivity. -Indirect measurements done with beams at international facilities with radioactive beams: TAMU and RIBF RIKEN. With help from colleagues, I will mention some theory advances, too.

scholarly journals Proton-Induced Reactions of Astrophysical Interest

2018 ◽  
Vol 184 ◽  
pp. 02001
Author(s):  
Thomas Chillery
Keyword(s):  
Cross Sections ◽  
Main Sequence ◽  
Nuclear Astrophysics ◽  
Big Bang ◽  
High Accuracy ◽  
Low Energy ◽  
Current Status ◽  
Main Sequence Stars ◽  
Big Bang Nucleosynthesis ◽  
Proton Induced Reactions

A discrepancy exists between the 6Li abundances predicted from big bang nucleosynthesis models and those measured in pre-main sequence stars. To further constrain the predicted abundances of 6Li in these stars, high accuracy measurements are required of reactions destroying 6Li. Namely 6Li(p,γ)7Be and 6Li(p,α) 3He. These have recently been studied at the Laboratory for Underground Nuclear Astrophysics (LUNA) to measure their low energy cross sections. I present both the campaign’s experimental setup and current status of the data analysis.

scholarly journals Investigation of 54Fe(α, n)57Ni Reaction for Low Activation Material Fe

2021 ◽  
Vol 2 (9) ◽  
pp. 826-829
Author(s):  
Ercan Yildiz ◽  
Saniye Tekerek
Keyword(s):  
Nuclear Reactions ◽  
Material Selection ◽  
Theoretical Calculations ◽  
Computer Code ◽  
Structural Materials ◽  
Nuclear Model ◽  
Model Code ◽  
S Factor ◽  
Low Energies ◽  
Talys 1.8

In fusion reactors, radioactivity can be controlled by effective material selection. Material selection is always important for efficient conversion of radioactivity to electrical energy.The selection of structural materials provides more efficient use of these structural materials with the results obtained from nuclear reactions. Low activation materials not only high in structural material performance and longer life, but also minimize related problems. Iron is an important element in fusion reactor technologies and astrophysical applications. For this reason, we obtained the theoretical cross-section values of the 54Fe(α, n)57Ni reaction in the range of 5-15 MeV (Mega electron volt) in this study. TALYS 1.8 (nuclear model code system) and NON-SMOKER (computer code) were used for theoretical calculations. Astrophysical S-factor values describing reactions at low energies were also calculated. In addition, reaction rate values were calculated with TALYS 1.8 and compared with EXFOR (experimental nuclear reaction data).

Chromospheric activity as a function of age in main-sequence stars

1966 ◽  
Vol 24 ◽  
pp. 40-43
Author(s):  
O. C. Wilson ◽  
A. Skumanich
Keyword(s):  
Main Sequence ◽  
The Sun ◽  
Main Sequence Stars ◽  
Tentative Conclusion ◽  
Chromospheric Activity ◽  
General Field ◽  
Large Clusters

Evidence previously presented by one of the authors (1) suggests strongly that chromospheric activity decreases with age in main sequence stars. This tentative conclusion rests principally upon a comparison of the members of large clusters (Hyades, Praesepe, Pleiades) with non-cluster objects in the general field, including the Sun. It is at least conceivable, however, that cluster and non-cluster stars might differ in some fundamental fashion which could influence the degree of chromospheric activity, and that the observed differences in chromospheric activity would then be attributable to the circumstances of stellar origin rather than to age.

On The Radii of Ap Stars

1976 ◽  
Vol 32 ◽  
pp. 49-55 ◽  
Author(s):  
F.A. Catalano ◽  
G. Strazzulla
Keyword(s):  
Observational Data ◽  
Line Width ◽  
Main Sequence ◽  
Main Sequence Stars ◽  
Ap Stars

SummaryFrom the analysis of the observational data of about 100 Ap stars, the radii have been computed under the assumption that Ap are main sequence stars. Radii range from 1.4 to 4.9 solar units. These values are all compatible with the Deutsch's period versus line-width relation.

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