Collision Processes Involving Highly Ionized Atoms

1951 ◽  
Vol 4 (4) ◽  
pp. 437
Author(s):  
ER Hill
Keyword(s):  
Quantum Theory ◽  
Cross Section ◽  
Cross Sections ◽  
Radiative Recombination ◽  
Inelastic Collisions ◽  
Electron Collision ◽  
Mechanical Methods ◽  
Classical Quantum ◽  
Collision Processes ◽  
The Cross

The cross section of FeXIV for inelastic collisions resulting in the transition from the 2P3/2 to the 2P1/2 state of the ion, for electron collision ionization, and for radiative recombination of FeXIV and MgX are calculated by wave mechanical methods. A method is given whereby radiative recombination cross sections of all highly ionized atoms may be calculated. Where possible the cross sections obtained are compared with corresponding results given by the classical quantum theory. Finally, the wave mechanical values are used to verify the general conclusion, obtained using classical quantum values of the cross sections, that the agitation temperature of the coronal electrons is about 106 �K.

scholarly journals Elastic and inelastic cross-sections of the mercury atom

1935 ◽  
Vol 151 (873) ◽  
pp. 256-274 ◽  
Author(s):  
F. L. Arnot ◽  
G. O. Baines ◽  
Herbert Stanley Allen
Keyword(s):  
Total Cross Section ◽  
Cross Section ◽  
Cross Sections ◽  
Inelastic Collision ◽  
Elastic Collision ◽  
Mercury Atom ◽  
Discrete Energy ◽  
Complete Knowledge ◽  
Collision Processes ◽  
The Cross

A considerable amount of experimental work has been done in investigating the total cross-section of an atom for collision with an electron in various gases. The total cross-section is measured by determining the number of electrons deflected out of a homogeneous beam, or which have their energy decreased, as the beam passes through the gas. For a complete knowledge of collision processes, it is necessary to know not only the total cross-section for collision but also the cross-section of the atom for various specific types of collision. The total cross-section can be divided into two main partial cross-sections—that for elastic collision and that for inelastic collision. The latter may be subdivided into the cross-section for excitation and the cross-section for ionization. The cross-section for excitation may then be further subdivided into the various cross-sections pertaining to the numerous discrete energy losses that the electron may suffer in its collision with the atom.

Inelastic collisions between ions and atoms

1952 ◽  
Vol 212 (1109) ◽  
pp. 235-248 ◽  
Keyword(s):  
Excited States ◽  
Cross Section ◽  
Cross Sections ◽  
Negative Ions ◽  
Inelastic Collisions ◽  
Electron Affinities ◽  
Atomic Collision ◽  
Low Energies ◽  
Low Energy Electron ◽  
The Cross

Charge-exchange cross-sections for H + , D + , O + 2 , H + 2 , O + , CO + and N + 2 in A; D + , O + and N + in Kr; D + , C + and Br + in Xe, and O + in H 2 O have been measured between 25 and 4000 eV energy by a method previously described. The normal atomic collision cross-sections rise to a maximum at a voltage which depends on the value of Δ E √ M for the process, M being the atomic mass and Δ E the energy defect of the reaction. Collisions between negative ions and atoms have been studied with the same apparatus, the cross-section of the detachment reaction X - + Y → X + e + Y — Δ E being obtained. For S - , Br - , I - , C - , P - , Li - in Ne, and H - in He, Ne, A, Kr, Xe, this rises with increasing energy of the incident ion. For O - in He, Ne, A, Kr, Xe, Cl - in He, Ne, A, Kr, Xe, and F - in Ne, Kr, Xe the cross-section at low energies is unexpectedly large for the value of Δ E √M. This may be interpreted as being due to the presence of excited states of these ions, of low electron affinities, in the beam. With O - , a low energy electron bombardment source gave smaller cross-sections, i.e. a smaller proportion of excited ions.

Rotationally inelastic collisions of orbitally degenerate molecules; maser action in OH and CH

1979 ◽  
Vol 368 (1732) ◽  
pp. 99-123 ◽  
Keyword(s):  
Low Temperature ◽  
Cross Section ◽  
Cross Sections ◽  
Born Approximation ◽  
Open Shell ◽  
Inelastic Collisions ◽  
Distorted Wave ◽  
Distorted Wave Born Approximation ◽  
The Cross ◽  
Maser Action

The theory of rotationally inelastic collisions between orbitally degenerate diatomic molecules and open-shell atoms is developed. Because of the orbital degeneracy two or more electronic potential energy surfaces are involved. Matrix elements of the interaction Hamiltonian are given, hyperfine coupling in the diatomic molecule also being included. From these it is apparent th at the parity of the initial Λ -doublet level will influence the inelastic scattering cross section for poles of interaction λ such that λ ≥ 2 Λ .An expression is developed for state-to-state cross sections using the restricted distorted wave Born approximation. A set of branching coefficients is defined which allows the representation of the parity dependence of the cross section in a simple parametric form. The theory is applied to collisional pumping as an excitation mechanism for interstellar maser action of OH and CH through the inversion of Λ -doublet populations. H atoms, H 2 , He, H + and H + 3 are considered as collision partners. Branching coefficients are tabulated for a variety of excitations from the rotational ground states. The sense of the parity dependence of the cross sections arises from the gross features of the interaction potential at medium and long range, and can be deduced using approximate theoretical surfaces or empirical models. An analogy is drawn with the experimental rates of rotational energy transfer in the closely related system H + NH 2 (Ã, 2 A 1 ), which are ca. 10 -9 cm 3 s -1 , and which have been successfully interpreted using the distorted wave Born approximation. These results are used to give qualitative predictions of population inversion in the Λ -doublets of OH, OD and CH in interstellar clouds. We show th at the ground J = 1 ½ doublet, and excited doublets of the F 1 manifold, of OH and OD will be inverted following collisions with H, H 2 and He. The J = 1/2 doublet of the F 2 manifold of OH and OD will be inverted by collisions with the ions H + and H + 3 . In CH low temperature collisions with H atoms will result in inversion of the ground J = 1 ½ doublet. Collisions with H 2 and He at low temperature result in cooling of the doublet. Implications for maser action are briefly discussed.

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.

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.

Inelastic collisions at low energies

1969 ◽  
Vol 47 (10) ◽  
pp. 1723-1729 ◽  
Author(s):  
A. Dalgarno
Keyword(s):  
Energy Loss ◽  
Cross Sections ◽  
Low Energy ◽  
Inelastic Collisions ◽  
Low Energies ◽  
Low Energy Electrons ◽  
The Cross ◽  
Loss Rates

A summary is presented of the processes by which low energy electrons lose energy in moving through the atmosphere and estimates are given of the cross sections and energy loss rates. The mechanisms by which thermal electrons cool are described and the cooling efficiencies are listed.

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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