scholarly journals New reaction rates for the destruction of 7Be during big bang nucleosynthesis measured at CERN/n_TOF and their implications on the cosmological lithium problem

2020 ◽  
Vol 239 ◽  
pp. 07001
Author(s):  
A. Mengoni ◽  
L.A. Damone ◽  
M. Barbagallo ◽  
O. Aberle ◽  
V. Alcayne ◽  
...  
Keyword(s):  
Energy Range ◽  
Thermal Energy ◽  
Cross Sections ◽  
Reaction Rates ◽  
Big Bang ◽  
Reaction Cross ◽  
Big Bang Nucleosynthesis ◽  
Destruction Rate ◽  
Viable Solution ◽  
Reaction Cross Sections

New measurements of the 7Be(n,α)4He and 7Be(n,p)7Li reaction cross sections from thermal to keV neutron energies have been recently performed at CERN/n_TOF. Based on the new experimental results, astrophysical reaction rates have been derived for both reactions, including a proper evaluation of their uncertainties in the thermal energy range of interest for big bang nucleosynthesis studies. The new estimate of the 7Be destruction rate, based on these new results, yields a decrease of the predicted cosmological 7Li abundance insufficient to provide a viable solution to the cosmological lithium problem.

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.

Calculation of proton total reaction cross sections for some target nuclei in incident energy range of 10–600 MeV

2010 ◽  
Vol 73 (10) ◽  
pp. 1700-1706 ◽  
Author(s):  
H. Büyükuslu ◽  
A. Kaplan ◽  
A. Aydin ◽  
E. Tel ◽  
G. Yıldırım
Keyword(s):  
Energy Range ◽  
Cross Sections ◽  
Incident Energy ◽  
Reaction Cross ◽  
Total Reaction ◽  
Reaction Cross Sections

scholarly journals Statistical model calculations of 72,73Ge(n,p) and 72,74Ge(n,α) reactions on natural Ge

2020 ◽  
Vol 15 ◽  
pp. 104
Author(s):  
S. Galanopoulos ◽  
R. Vlastou ◽  
P. Demetriou ◽  
M. Kokkoris ◽  
C. T. Papadopoulos ◽  
...  
Keyword(s):  
Statistical Model ◽  
Energy Range ◽  
Neutron Energy ◽  
Cross Sections ◽  
Reaction Cross ◽  
Model Calculations ◽  
Monoenergetic Neutron ◽  
Theoretical Investigations ◽  
Equilibrium Emission ◽  
Reaction Cross Sections

Systematic experimental and theoretical investigations of the 72,73Ge(n,p)72,73 Ga and 72,74Ge(n,α)69,71Znm reaction cross sections are presented in the energy range from thresh- old to about 17 MeV neutron energy. The above reaction cross sections were measured from 8.8 to 11.4 MeV by using the activation method, relative to the 27Al(n,α)24Na refer- ence reaction. The quasi-monoenergetic neutron beams were produced via the 2H(d,n)3He reaction at the 5 MV VdG Tandem T11/25 accelerator of NCSR “Demokritos”. Statisti- cal model calculations using the code EMPIRE-II (version 2.19) taking into consideration pre-equilibrium emission were performed on the data measured in this work as well as on data reported in literature.

Microscopic analysis of the energy dependence of the 6He, 6Li + 28Si total reaction cross sections in the energy range E = 5−50 A MeV

2008 ◽  
Vol 72 (3) ◽  
pp. 356-360
Author(s):  
K. V. Lukyanov ◽  
E. V. Zemlyanaya ◽  
V. K. Lukyanov ◽  
I. N. Kukhtina ◽  
Yu. E. Penionzhkevich ◽  
...  
Keyword(s):  
Energy Range ◽  
Energy Dependence ◽  
Cross Sections ◽  
Microscopic Analysis ◽  
Reaction Cross ◽  
Total Reaction ◽  
Reaction Cross Sections

Reaction cross sections for protons in the energy range 220–570 MeV

1972 ◽  
Vol 183 (1) ◽  
pp. 81-104 ◽  
Author(s):  
P.U. Renberg ◽  
D.F. Measday ◽  
M. Pepin ◽  
P. Schwaller ◽  
B. Favier ◽  
...  
Keyword(s):  
Energy Range ◽  
Cross Sections ◽  
Reaction Cross ◽  
Reaction Cross Sections

STAU-CATALYZED BIG-BANG NUCLEOSYNTHESIS AND NUCLEAR CLUSTER MODEL

2009 ◽  
Vol 24 (11) ◽  
pp. 2076-2083 ◽  
Author(s):  
M. KAMIMURA ◽  
Y. KINO ◽  
E. HIYAMA
Keyword(s):  
Cross Sections ◽  
Cluster Model ◽  
Nuclear Reactions ◽  
Light Element ◽  
Bound State ◽  
Big Bang ◽  
Reaction Cross ◽  
Big Bang Nucleosynthesis ◽  
Model Calculations ◽  
Three Body

Three-body cluster-model calculations are performed for the new types of big-bang nucleosynthesis (BBN) reactions that are calalyzed by a supersymmetric (SUSY) particle stau, a scalar partner of the tau lepton. If a stau has a lifetime ≳ 103s, it would capture a light element previously synthesized in standard BBN and form a Coulombic bound state. The bound state, an exotic atom, is expected to induce various reactions, such as (αX-) + d → 6 Li + X-, in which a negatively charged stau (denoted as X-) works as a catalyzer. Recent literature papers have claimed that some of these stau-catalyzed reactions have significantly large cross sections so that inclusion of the reactions into the BBN network calculation can change drastically abundances of some elements, giving not only a solution to the 6 Li -7 Li problem (calculated underproduction of 6 Li by ~ 1000 times and overproduction of 7 Li +7 Be by ~ 3 times) but also a constraint on the lifetime and the primordial abundance of the elementary particle stau. However, most of these literature calculations of the reaction cross sections were made assuming too naive models or approximations that are unsuitable for those complicated low-energy nuclear reactions. We use a few-body calculational method developed by the authors, and provides precise cross sections and rates of the stau-catalyzed BBN reactions for the use in the BBN network calculation.

scholarly journals Chemical Reaction Kinematics

1968 ◽  
Vol 23 (12) ◽  
pp. 2080-2083 ◽  
Author(s):  
D. Hyatt ◽  
K. Lacmann
Keyword(s):  
Energy Range ◽  
Cross Section ◽  
Mass Spectrometer ◽  
Cross Sections ◽  
Impulse Approximation ◽  
Reaction Cross ◽  
Molecule Reaction ◽  
Polarization Theory ◽  
Reaction Cross Sections

A Bendix time of flight mass spectrometer has been modified to enable the determination of some ion-molecule reaction cross sections in the energy range 1 — 100 eV.In the reactions studiedX+ + D2 → XD++Dwhere X may be Ar, N2 or CO, the results obtained agree with the predictions of the polarization theory in the range below 10 eV despite the fact that no intermediate complex is formed at these energies. Between about 10—50 eV where spectator stripping occurs the cross section follows an approximate E-l dependence. Above these energies the results are consistent with a transition to a region in which knock-on processes predominate and where an impulse approximation treatment would be valid.

Proton total reaction cross sections for the doubly magic nucleiO16,Ca40, andPb208in the energy range 20-50 MeV

1975 ◽  
Vol 12 (4) ◽  
pp. 1167-1175 ◽  
Author(s):  
R. F. Carlson ◽  
A. J. Cox ◽  
J. R. Nimmo ◽  
N. E. Davison ◽  
S. A. Elbakr ◽  
...  
Keyword(s):  
Energy Range ◽  
Cross Sections ◽  
Reaction Cross ◽  
Total Reaction ◽  
Reaction Cross Sections

scholarly journals Thermonuclear Reaction Rates for Reactions Leading to N = 28 Nuclei

1995 ◽  
Vol 48 (1) ◽  
pp. 125
Author(s):  
A.J Morton ◽  
DG Sargood
Keyword(s):  
Statistical Model ◽  
Nuclear Reaction ◽  
Cross Sections ◽  
Optical Model ◽  
Reaction Rates ◽  
Reaction Cross ◽  
Model Parameters ◽  
Thermonuclear Reaction ◽  
Model Calculations ◽  
Reaction Cross Sections

Nuclear reaction cross sections derived from statistical-model calculations have been used in the calculation of thermonuclear reaction rates for 36 nuclei at temperatures that are representative of the interiors of evolving stars and supernovae as nucleosynthesis approaches the production of nuclei with N = 28. The statistical-model calculations used optical-model parameters in the particle channels which had been selected to give the best overall agreement between theoretical and experimental cross sections for reactions on stable target nuclei in the mass and energy ranges of importance for the stellar conditions of interest. The optical-model parameters used, and the stellar reaction rates obtained, are tabulated. Comparisons are made between these stellar rates and those from other statistical-model calculations in the literature.

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