scholarly journals The Interaction of Neutrons with 7Be at BBN Temperatures: Lack of Standard Nuclear Solution to the “Primordial 7Li Problem”

2020 ◽  
Vol 227 ◽  
pp. 01007 ◽  
Author(s):  
M. Gai ◽  
E.E. Kading ◽  
M. Hass ◽  
K.M. Nollett ◽  
S.R. Stern ◽  
...  
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
High Energy ◽  
Big Bang ◽  
Alpha Particles ◽  
P Wave ◽  
Recent Measurement ◽  
S Wave ◽  
Big Bang Nucleosynthesis ◽  
The Cross

We report the first measurement of alpha-particles from the interaction of neutrons with 7Be at “temperatures” of Big Bang Nucleosynthesis (BBN). We measured the Maxwellian averaged cross sections (MACS), with neutron beams produced by the LiLiT at the SARAF in Israel (with kT = 49.5 keV hence 0.57 GK). In addition, we measured the cross section of the 7Be(n,p) reaction, which is in excellent agreement with the recent measurement of the n_TOF collaboration, further substantiating our method as a demonstration of “proof of principle”. The cross section for the 7Be(n,ga) and the 7Be(n,a) reaction measured in the “BBN window” is considerably smaller than compiled by Wagoner in 1969 and used today in Big Bang Nucleosynthesis (BBN). We also rule out a hitherto unknown resonance in 8Be at the BBN window, that was conjectured as a possible standard nuclear physics solution to the “Primordial 7Li Problem”. Together with previous results, we deduce a new Wagoner-like Rate for the destruction of 7Be by neutrons which is based on all current measured data. We conclude the lack of a standard nuclear solution to the “Primordial 7Li Problem”. Our upper limit on the cross sections for the high energy alpha-particles is in agreement with recent measurement of the n_TOF collaboration, but it is considerably smaller than the p-wave extrapolation of the Kyoto collaboration. We measured the alpha-particles from the 7Be(n,gi)8Be*(3.03 MeV) reaction, which is considerably larger than a previous s-wave estimate. Hence, in contrast, we conclude s-wave dominance at BBN energies, as would be expected due to the broad (122 keV) low lying 2” state at En = 10 keV.

scholarly journals Total cross sections of eγ → $$ eX\overline{X} $$ processes with X = μ, γ, e via multiloop methods

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Roman N. Lee ◽  
Alexey A. Lyubyakin ◽  
Vyacheslav A. Stotsky
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Elliptic Integral ◽  
High Energy ◽  
Calculation Methods ◽  
Complete Elliptic Integral ◽  
Total Cross Sections ◽  
Multiloop Calculation ◽  
The Cross ◽  
Analytical Expressions

Abstract Using modern multiloop calculation methods, we derive the analytical expressions for the total cross sections of the processes e−γ →$$ {e}^{-}X\overline{X} $$ e − X X ¯ with X = μ, γ or e at arbitrary energies. For the first two processes our results are expressed via classical polylogarithms. The cross section of e−γ → e−e−e+ is represented as a one-fold integral of complete elliptic integral K and logarithms. Using our results, we calculate the threshold and high-energy asymptotics and compare them with available results.

Inelastic cross sections of nucleons and π mesons in carbon and lead near 100 GeV

1968 ◽  
Vol 46 (10) ◽  
pp. S694-S696 ◽  
Author(s):  
A. V. Alakoz ◽  
V. N. Bolotov ◽  
M. I. Devishev ◽  
L. F. Klimanova ◽  
A. P. Shmeleva
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Cosmic Ray ◽  
High Energy ◽  
Active Particle ◽  
Particle Interactions ◽  
Active Particles ◽  
The Cross

An experiment to measure the cross section for high-energy cosmic-ray neutrons and charged nuclear-active particle interactions with Pb and C nuclei has been carried out at an altitude of 2 000 m. Large spark chambers were used in a detector which selected neutrons and charged nuclear-active particles in the region of 100 GeV. The results are σπ(nPb) = (1.65 ± 0.17) barn, σπ(nC) = (0.204 ± 0.02) barn, σπ(πPb) = (1.53 ± 0.17) barn, σπ(πC) = (0.168 ± 0.017) barn.

scholarly journals Investigating Scalar Unparticle Production at Collisions with Polarized Beams in Unparticle Physics

2020 ◽  
Vol 36 (4) ◽  
Author(s):  
Le Nhu Thuc ◽  
Dao Thi Le Thuy
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Z Boson ◽  
Collision Energy ◽  
High Energy ◽  
Polarized Beams ◽  
Boson Exchange ◽  
The Cross ◽  
Muon Colliders ◽  
Energy Frontier

Scalar unparticle production in the process is studied from unparticle physics perspective. We have calculated and evaluated the cross sections for muon and Z boson exchange when the  beams are initially polarized. Numerical calculations show that the cross section of collisions depends strongly on the polarized condition of the initial beams and the collision energy . The results are plotted in the energy reach available at the present accelerators and the future high energy frontier muon colliders as shown in the scheme by Muon Accelerator Program (MAP) and other different colliders.

scholarly journals EMPIRICAL FORMALISM FOR PROJECTILE FRAGMENTATION AND PRODUCTION OF NEW NEUTRON-RICH NUCLEI WITH RIBS

1998 ◽  
Vol 13 (33) ◽  
pp. 2665-2678 ◽  
Author(s):  
DEBASIS BHOWMICK ◽  
ALOK CHAKRABARTI ◽  
D. N. BASU ◽  
PREMOMOY GHOSH ◽  
RANJANA GOSWAMI
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Ion Beam ◽  
Production Cross ◽  
High Energy ◽  
Exotic Nuclei ◽  
Radioactive Beams ◽  
Fragment Separator ◽  
Projectile Fragment ◽  
The Cross

The projectile fragment separator type radioactive ion beam (RIB) facilities, being developed in different laboratories, provide the scope for producing many new exotic nuclei through fragmentation of high energy radioactive ion (RI) beams. A new empirical parametrization for the estimation of cross-sections of projectile fragments has been prescribed for studying the advantages and limitations of high energy RI beams for the production of new exotic nuclei. The parametrization reproduces the experimental data for the production of fragments from neutron-rich projectiles accurately in contrast to the existing parametrization which tends to overestimate the cross-section of neutron-rich fragments in most cases. The modified formalism has been used to compute the cross-sections of neutron-rich species produced by fragmentation of radioactive projectiles (RIBs). It has been found that, given any limit of production cross-section, the exoticity of the fragment increases rather slowly and shows a saturation tendency as the projectile is made more and more exotic. This essentially limits, to an extent, the utility of very neutron-rich radioactive beams vis-a-vis production of new neutron-rich exotic species.

scholarly journals Scattering Cross Sections in Argon from Electron Transport Parameters

1982 ◽  
Vol 35 (1) ◽  
pp. 35 ◽  
Author(s):  
GN Haddad ◽  
TF O'Malley
Keyword(s):  
Phase Shift ◽  
Cross Section ◽  
Cross Sections ◽  
Lateral Diffusion ◽  
Phase Shifts ◽  
P Wave ◽  
Transport Parameters ◽  
S Wave ◽  
Wave Phase ◽  
Range Theory

Previously determined experimental drift velocities Vdr and ratios of lateral diffusion coefficient to mobility DT/µ have been refitted directly with a three parameter modified effective range theory (MER T) representation of the S wave phase shift, a one parameter fit to the P wave phase shift and fixed higher partial wave phase shifts. The MERT representation now extends to 1·0 eV, a threefold extension of the energy range of the MERT fit reported by Milloy et al. (1977). The total cross section derived from the phase shifts is also reported, together with the differential cross section at 1·0 eV which is compared with a previous experimental determination.

scholarly journals Deuteron breakup at zero angle in the Coulomb nuclear field

2019 ◽  
Vol 204 ◽  
pp. 10011
Author(s):  
Igor Sitnik
Keyword(s):  
Cross Section ◽  
High Precision ◽  
Cross Sections ◽  
High Energy Physics ◽  
Nuclear Research ◽  
High Energy ◽  
Deuteron Breakup ◽  
The Cross ◽  
Cross Section Maximum ◽  
Energy Physics

Deuteron breakup cross sections on the C and CH2 targets have been measured up to the proton internal momenta of 0.3 GeV/c. The cross-sections 12C(d, p)X and 1H(d, p)X reactions have been obtained with high precision. The obtained data are compared with previous measurements. The behavior features in the vicinity of the cross section maximum were studied in dependence on the transversal momentum in the region of 0.01 < pt < 0.16 GeV/c. The measurements have been performed at the Veksler Baldin Laboratory of High Energy Physics of the Joint Institute for Nuclear Research.

scholarly journals New measurement of the cross section of the big bang nucleosynthesis reaction $D(\alpha,\gamma)^{6}Li$ and its astrophysical impact

2010 ◽  
Author(s):  
Feirouz Hammache ◽  
Daniel Galaviz ◽  
K. Sümmerer ◽  
S. Typel ◽  
F. Uhlig ◽  
...  
Keyword(s):  
Cross Section ◽  
Big Bang ◽  
Big Bang Nucleosynthesis ◽  
The Cross ◽  
The Big Bang

Resonance charge transfer between H(1s) and H + calculated by means of an approximation based on an expansion in atomic eigenfunctions

1961 ◽  
Vol 264 (1319) ◽  
pp. 547-557 ◽  
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Atomic Hydrogen ◽  
High Energy ◽  
Wave Functions ◽  
Final States ◽  
Energy Limit ◽  
Full Account ◽  
The Cross ◽  
Resonance Charge

An expression for the cross-section describing electron capture by protons in atomic hydrogen is derived from an expansion based on atomic wave functions. Full account is taken of momentum transfer and of the non-orthogonality of the wave functions of the initial and final states by the method due to Bates. The cross-sections have been computed for proton energies from 100 to 1 MeV. In the low energy limit, the results agree with the p.s.s. calculations of Dalgarno & Yadav and in the high energy limit with the calculations of Brinkm an & Kramers.

scholarly journals n + 7Be Cross-Sections of Astrophysical Interest at the CERN n_TOF Facility

Proceedings ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 12
Author(s):  
Mario Mastromarco ◽  
Lucia Damone ◽  
Massimo Barbagallo ◽  
Keyword(s):  
Cross Section ◽  
Neutron Energy ◽  
Cross Sections ◽  
Big Bang ◽  
Neutron Energy Range ◽  
Big Bang Nucleosynthesis ◽  
Destruction Rate ◽  
A Value ◽  
First Time ◽  
Rule Out

One of the possible explanations of the so-called Cosmological Lithium Problem (CLIP), i.e., the large overestimate of the primordial 7 Li abundance by the standard Big Bang Nucleosynthesis theory (BBN), is related to an incorrect underestimation of the 7 Be destruction rate by neutron-induced reactions. To verify this possibility, the n + 7 Be reactions have been investigated at n_TOF (CERN) in a wide neutron energy range, taking advantage of the new high-flux experimental area (EAR2) and specifically developed experimental setups. The 7 Be(n, α ) 4 He cross section, measured for the first time from thermal to 10 keV neutron energy, was found consistent with previous estimates. A 10% increase of the 7 Be destruction rate was instead determined on the basis of the 7 Be(n, p) 7 Li cross section measured at n_TOF from thermal to 300 keV neutron energy, a value clearly insufficient to provide a solution to the Cosmological Lithium Problem. Combined together, the two measurements finally rule out neutron-induced reactions on 7 Be as a possible explanation of the CLIP.

scholarly journals ANALYSIS OF HIGH ENERGY K+K- PHOTOPRODUCTION ON HYDROGEN

2005 ◽  
Vol 20 (02n03) ◽  
pp. 581-583
Author(s):  
Ł. BIBRZYCKI ◽  
L. LEŚNIAK ◽  
A. P. SZCZEPANIAK
Keyword(s):  
Effective Mass ◽  
Cross Section ◽  
Good Description ◽  
Mass Range ◽  
High Energy ◽  
Mass Region ◽  
P Wave ◽  
S Wave ◽  
Mass Distributions ◽  
Scalar Resonances

We have analyzed the γp→pK+K- reaction in the K+K- effective mass region around the mass of the ϕ(1020) meson. The interference of the S-wave contribution with the P-wave has been studied. Both scalar resonances f0(980) and a0(980) have been taken into account. We obtained a good description of the available experimental data, in particular the mass distributions and the moments of the kaon angular distribution. Our calculations give values of the integrated S-wave total photoproduction cross section between 4 and 7 nb for the K+K- effective mass range around the ϕ(1020) mass and at the laboratory photon energy near 5 GeV. These numbers favor lower experimental estimates obtained at DESY.

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