Processus non réactifs dans les collisions H2 + H(2s) aux énergies thermiques

1990 ◽  
Vol 68 (2) ◽  
pp. 206-213
Author(s):  
B. Stern
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Cross Section ◽  
Cross Sections ◽  
Differential Rotation ◽  
Collision Energy ◽  
Close Coupling ◽  
Interference Phenomenon ◽  
The Cross ◽  
Energy Surfaces

Ab initio calculations of energy surfaces of the system [Formula: see text] corresponding to dissociation into H(2s) + H2 (X, 1Σg+) and H(2p0) + H2(X) are presented. For a thermal collision energy (0,064 eV), multistate close-coupling calculations are performed. In relation to experiments in progress, elastic and inelastic differential rotation cross sections are shown. For the quenching of H(2s) by H2:[Formula: see text]the cross section is obtained from an interference phenomenon between the elastic amplitudes associated to the two molecular states related to the entrance and exit channels, respectively. After criticizing the models used for the collision, which are valid only for small scattering angles, improvements are proposed in conclusion.[Journal translation]

A measurement of the cross section for production of He + (2 S ) ions by electron impact excitation of ground state helium ions

1966 ◽  
Vol 290 (1420) ◽  
pp. 74-93 ◽  
Keyword(s):  
Plane Wave ◽  
Cross Section ◽  
Cross Sections ◽  
Absolute Magnitude ◽  
Impact Excitation ◽  
Electron Impact Excitation ◽  
Close Coupling ◽  
Born Cross Section ◽  
The Absolute ◽  
The Cross

A crossed beams method has been used to measure the cross section for the production of He + (2 S ) by electrons incident upon He + (1 S ) in the energy range from threshold to 750 eV. The cross section was measured in arbitrary units with an accuracy of ± 5 % and at the higher energies its energy dependence is in close agreement with that calculated by means of the plane-wave Born approximation. Consequently the cross section has been normalized to the plane-wave Born cross section at energies between 435 and 750 eV to obtain the absolute magnitude. An independent estimate of the absolute magnitude was made to with in ± 30 % using only the experimental parameters, and the absolute cross sections given by the two methods agree within the experimental uncertainties. The normalized cross section is compared with cross sections given by the close-coupling approximation and various Coulomb-Born approximations. At the lower energies the normalized cross section is considerably smaller than any of the theoretical values, but the measurements are consistent with the existence of a finite cross section at threshold if the energy spread of the electron beam is taken in to account.

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.

Ladungsaustausch zwischen Ionen und Atomen der Edelgase bei Stoßenergien unterhalb 200 eV

1969 ◽  
Vol 24 (11) ◽  
pp. 1716-1720
Author(s):  
H. Schlumbohm
Keyword(s):  
Cross Section ◽  
Charge Exchange ◽  
Cross Sections ◽  
Collision Energy ◽  
Threshold Energy ◽  
Strong Increase ◽  
Published Data ◽  
Slow Ions ◽  
Endothermic Process ◽  
The Cross

Charge exchange cross sections for the four systems He+, Ne+ + Ar, Kr have been measured, ap­plying slow ions gathering techniques. The values are several 1O-16 cm2 and are almost constant between 20 and 200 eV collision energy. The comparison with previously published data for charge exchange into optically excited higher states of the ions show that these reactions prefer at least at 25 to 30% endothermic channels instead of the exothermic one without excitation. - Additionally the cross section of the endothermic process Ar++Ne was measured. Above a threshold energy of 17 eV it shows a strong increase and a constant value of 7 · 10-17 cm2 between 20 and 200 eV.

Experimental Studies Of Multilayer Glass Structures On Compression, Compression With Bending And Simple Bending

2019 ◽  
pp. 22-30
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Applied Load ◽  
Experimental Studies ◽  
Strength Properties ◽  
Research Topic ◽  
Normative Values ◽  
Laminated Glass ◽  
The Cross ◽  
Experimental Values

The work of multilayer glass structures for central and eccentric compression and bending are considered. The substantiation of the chosen research topic is made. The description and features of laminated glass for the structures investigated, their characteristics are presented. The analysis of the results obtained when testing for compression, compression with bending, simple bending of models of columns, beams, samples of laminated glass was made. Overview of the types and nature of destruction of the models are presented, diagrams of material operation are constructed, average values of the resistance of the cross-sections of samples are obtained, the table of destructive loads is generated. The need for development of a set of rules and guidelines for the design of glass structures, including laminated glass, for bearing elements, as well as standards for testing, rules for assessing the strength, stiffness, crack resistance and methods for determining the strength of control samples is emphasized. It is established that the strength properties of glass depend on the type of applied load and vary widely, and significantly lower than the corresponding normative values of the strength of heat-strengthened glass. The effect of the connecting polymeric material and manufacturing technology of laminated glass on the strength of the structure is also shown. The experimental values of the elastic modulus are different in different directions of the cross section and in the direction perpendicular to the glass layers are two times less than along the glass layers.

Rotational de-excitations of C3H+ (1Σ+) by collision with He: new ab initio potential energy surface and scattering calculations

2020 ◽  
Vol 494 (4) ◽  
pp. 5675-5681 ◽  
Author(s):  
Sanchit Chhabra ◽  
T J Dhilip Kumar
Keyword(s):  
Potential Energy ◽  
Potential Energy Surface ◽  
Ab Initio ◽  
Cross Sections ◽  
Energy Surface ◽  
Molecular Ions ◽  
Basis Set ◽  
Rate Coefficients ◽  
Close Coupling ◽  
Collisional Rate Coefficients

ABSTRACT Molecular ions play an important role in the astrochemistry of interstellar and circumstellar media. C3H+ has been identified in the interstellar medium recently. A new potential energy surface of the C3H+–He van der Waals complex is computed using the ab initio explicitly correlated coupled cluster with the single, double and perturbative triple excitation [CCSD(T)-F12] method and the augmented correlation consistent polarized valence triple zeta (aug-cc-pVTZ) basis set. The potential presents a well of 174.6 cm−1 in linear geometry towards the H end. Calculations of pure rotational excitation cross-sections of C3H+ by He are carried out using the exact quantum mechanical close-coupling approach. Cross-sections for transitions among the rotational levels of C3H+ are computed for energies up to 600 cm−1. The cross-sections are used to obtain the collisional rate coefficients for temperatures T ≤ 100 K. Along with laboratory experiments, the results obtained in this work may be very useful for astrophysical applications to understand hydrocarbon chemistry.

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.

scholarly journals Asymptotic Behavior of Stable Structures Made of Beams

2021 ◽  
Author(s):  
Georges Griso ◽  
Larysa Khilkova ◽  
Julia Orlik ◽  
Olena Sivak
Keyword(s):  
Asymptotic Behavior ◽  
Cross Section ◽  
Cross Sections ◽  
Linear Elasticity ◽  
Circular Cross Section ◽  
Linear Elasticity Theory ◽  
Linear Elastic ◽  
The Cross ◽  
Small Rotation ◽  
Stable Structures

AbstractIn this paper, we study the asymptotic behavior of an $\varepsilon $ ε -periodic 3D stable structure made of beams of circular cross-section of radius $r$ r when the periodicity parameter $\varepsilon $ ε and the ratio ${r/\varepsilon }$ r / ε simultaneously tend to 0. The analysis is performed within the frame of linear elasticity theory and it is based on the known decomposition of the beam displacements into a beam centerline displacement, a small rotation of the cross-sections and a warping (the deformation of the cross-sections). This decomposition allows to obtain Korn type inequalities. We introduce two unfolding operators, one for the homogenization of the set of beam centerlines and another for the dimension reduction of the beams. The limit homogenized problem is still a linear elastic, second order PDE.

ISOSPIN DECOMPOSITION OF pp → NNππ CROSS SECTIONS — DO WE SEE A SIGN OF Δ(1600) EXCITATION IN THE nnπ+π+ CHANNEL?

2009 ◽  
Vol 24 (02n03) ◽  
pp. 450-453
Author(s):  
◽  
T. SKORODKO ◽  
M. BASHKANOV ◽  
D. BOGOSLOWSKY ◽  
H. CALÉN ◽  
...  
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Differential Cross ◽  
Pion Production ◽  
Significant Contribution ◽  
Differential Cross Sections ◽  
Pp Collisions ◽  
Theoretical Predictions ◽  
Order Of Magnitude ◽  
The Cross

The two-pion production in pp-collisions has been investigated in exclusive measurements from threshold up to Tp = 1.36 GeV . Total and differential cross sections have been obtained for the channels pnπ+π0, ppπ+π-, ppπ0π0 and also nnπ+π+. For intermediate incident energies Tp > 1 GeV , i.e. in the region, which is beyond the Roper excitation but at the onset of ΔΔ excitation the total ppπ0π0 cross section falls behind theoretical predictions by as much as an order of magnitude near 1.2 GeV, whereas the nnπ+π+ cross section is a factor of five larger than predicted. A model-unconstrained isospin decompostion of the cross section points to a significant contribution of an isospin 3/2 resonance other than the Δ(1232). As a possible candidate the Δ(1600) is discussed.

Intermolecular potential energy surfaces and spectra of Ne–HCN complex from ab initio calculations

2001 ◽  
Vol 114 (2) ◽  
pp. 764 ◽  
Author(s):  
Garold Murdachaew ◽  
Alston J. Misquitta ◽  
Robert Bukowski ◽  
Krzysztof Szalewicz
Keyword(s):  
Potential Energy ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Potential Energy Surfaces ◽  
Intermolecular Potential ◽  
Energy Surfaces

scholarly journals The Cross Section for the J = 0 → 2 Rotational Excitation of Hydrogen by Slow Electrons

1969 ◽  
Vol 22 (6) ◽  
pp. 715 ◽  
Author(s):  
RW Crompton ◽  
DK Gibson ◽  
AI McIntosh
Keyword(s):  
Momentum Transfer ◽  
Cross Section ◽  
Cross Sections ◽  
Vibrational Excitation ◽  
The Cross ◽  
Excitation Processes ◽  
Slow Electrons ◽  
And Diffusion ◽  
Momentum Transfer Cross Section ◽  
Section Analysis

The results of electron drift and diffusion measurements in parahydrogen have been analysed to determine the cross sections for momentum transfer and for rotational and vibrational excitation. The limited number of possible excitation processes in parahydrogen and the wide separation of the thresholds for these processes make it possible to determine uniquely the J = 0 → 2 rotational cross section from threshold to 0.3 eV. In addition, the momentum transfer cross section has been determined for energies less than 2 eV and it is shown that, near threshold, a vibrational cross section compatible with the data must lie within relatively narrow limits. The problems of uniqueness and accuracy inherent in the swarm method of cross section analysis are discussed. The present results are compared with other recent theoretical and experimental determinations; the agreement with the most recent calculations of Henry and Lane is excellent.

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