scholarly journals GENETIC PROGRAMMING APPROACH FOR ELECTRON-ALKALI-METAL ATOM COLLISIONS

2006 ◽  
Vol 20 (32) ◽  
pp. 5463-5471 ◽  
Author(s):  
SALAH YASEEN EL-BAKRY ◽  
AMR RADI
Keyword(s):  
Experimental Data ◽  
Genetic Programming ◽  
Cross Sections ◽  
Alkali Metal Atom ◽  
Intermediate Energy ◽  
Target Atom ◽  
Programming Approach ◽  
Dipole Polarizability ◽  
Total Cross Sections ◽  
Alkali Atoms

New technique is presented for modeling the total cross sections of electron scattering by Na, K, Rb and Cs atoms in the low and intermediate energy regions. The calculations have been performed in the framework of genetic programming (GP) technique. The GP has been running based on the experimental data of the total collisional cross sections to produce the total cross sections for each target atom. The incident energy and atomic number as well as the static dipole polarizability have been used as input variables to find the functions that describe the total collisional cross sections of the scattering of electrons by alkali atoms. The experimental, calculated and predicted total collisional cross sections are compared. The discovered functions show a good match to the experimental data.

DISCOVERED FUNCTION FOR POSITRON COLLISIONS WITH ALKALI-METAL ATOMS USING GENETIC PROGRAMMING

2007 ◽  
Vol 18 (03) ◽  
pp. 351-358 ◽  
Author(s):  
SALAH YASEEN EL-BAKRY ◽  
AMR RADI
Keyword(s):  
Experimental Data ◽  
Genetic Programming ◽  
Cross Sections ◽  
Target Atom ◽  
Dipole Polarizability ◽  
Sodium Potassium ◽  
Intermediate Energies ◽  
Alkali Atoms ◽  
Input Variables ◽  
Positron Collisions

Genetic programming (GP) has been used to discover the function that describes the collisions of positrons with sodium, potassium, rubidium and cesium atoms at low and intermediate energies. The GP has been running based on experimental data of the total collisional cross sections to produce the total cross sections for each target atom. The incident energy and the static dipole polarizability of the alkali target atom have been used as input variables to find the discovered function. The experimental, calculated and predicted total collisional cross sections are compared. The discovered function shows a good match to the experimental data. We find that the GP technique is able to improve upon more traditional methods. To our knowledge, this is the first application of the GP technique to the data of positron collisions with alkali atoms at low and intermediate energies.

Some comments on positron–atom scattering at intermediate energy

1982 ◽  
Vol 60 (4) ◽  
pp. 558-564 ◽  
Author(s):  
F. W. Byron Jr.
Keyword(s):  
Finite Number ◽  
Cross Sections ◽  
Infinite Number ◽  
Intermediate Energy ◽  
Total Cross Sections ◽  
Type Approximation ◽  
Atom Scattering ◽  
Target States

A brief survey of available theoretical techniques is given for positron–atom scattering. The distinction between methods involving a finite number of target states and those with an infinite number of target states is emphasized. The situation regarding total cross sections is summarized, and a new, non-perturbative, eikonal-type approximation, based on the work of Wallace, is introduced.

scholarly journals Energy Dependence of Total Cross Sections for Reactions with 4, 6he, 6, 7, 9li Nuclei

KnE Energy ◽  
2018 ◽  
Vol 3 (1) ◽  
pp. 21
Author(s):  
Yu Penionzhkevich ◽  
Yu Sobolev ◽  
V Samarin ◽  
M Naumenko
Keyword(s):  
Experimental Data ◽  
Energy Range ◽  
Numerical Solution ◽  
Energy Dependence ◽  
Cross Sections ◽  
Beam Energy ◽  
Microscopic Analysis ◽  
Time Dependent ◽  
Total Cross Sections ◽  
Good Agreement

The paper presents the results of measurement of the total cross sections for reactions 4,6He + Si and 6,7,9Li + Si in the beam energy range 5−50 A⋅MeV. The enhancements of the total cross sections for reaction 6He + Si compared with reaction 4He + Si, and 9Li + Si compared with reactions 6,7Li + Si have been observed. The performed microscopic analysis of total cross sections for reactions 6He + Si and 9Li + Si based on numerical solution of the time-dependent Schrödinger equation for external neutrons of projectile nuclei 6He and 9Li yielded good agreement with experimental data.

scholarly journals Close Coupling Theory of Positron Scattering from Alkali Atoms

1994 ◽  
Vol 47 (6) ◽  
pp. 721 ◽  
Author(s):  
Jim Mitroy ◽  
Kurunathan Ratnavelu
Keyword(s):  
Cross Sections ◽  
Alkali Atom ◽  
Coupling Theory ◽  
Positron Scattering ◽  
Close Coupling ◽  
Total Cross Sections ◽  
Hartree Fock ◽  
Atom Scattering ◽  
Alkali Atoms ◽  
Rearrangement Process

The close coupling equatious for positron-alkali atom scattering are written as a set of coupled momentum-space Lippmann-Schwinger equations. The alkali atom is represented by a frozen-core model based upon the Hartree-Fock approximation. The interaction between the positronium and the residual ion is modified by the inclusion of a core potential. Similarly, a core term is present in the interaction describing the rearrangement process. Close coupling calculations of positron scattering from sodium are performed in a model containing multiple sodium (3s, 3p, 4s, 3d, 4p) and positronium (Is, 2s, 2p) states. Cross sections are reported for an energy range from threshold to 50�eV; the total cross sections are in agreement with experimental data.

scholarly journals Do we understand near-forward elastic scattering up to TeV energies?

2015 ◽  
Vol 30 (08) ◽  
pp. 1542006 ◽  
Author(s):  
Claude Bourrely ◽  
Jacques Soffer ◽  
Tai Tsun Wu
Keyword(s):  
Experimental Data ◽  
Elastic Scattering ◽  
Cross Sections ◽  
Phenomenological Model ◽  
Experimental Results ◽  
Proton Proton ◽  
Total Cross Sections

In 1970, on purely theoretical grounds, all total hadronic total cross-sections were predicted to increase without limit for higher and higher energies. This was contrary to the conventional belief at that time. In 1978, an accurate phenomenological model was formulated for the case of proton–proton and antiproton-proton interactions. The parameters for this model were slightly improved in 1984 using the additional available experimental data. Since then, for 30 years these parameters have not changed. This development, including especially the difficult task of formulating this phenomenological model and the comparison of the predictions of this model with later experimental results, is summarized.

scholarly journals The role of N*(2120) nucleon resonance in KΛ(1520) photon and hadronic productions

2014 ◽  
Vol 29 ◽  
pp. 1460244
Author(s):  
Ju-Jun Xie ◽  
En Wang ◽  
Bo-Chao Liu ◽  
J. Nieves
Keyword(s):  
Experimental Data ◽  
Invariant Mass ◽  
Cross Sections ◽  
Dalitz Plot ◽  
Total Cross Sections ◽  
Effective Lagrangian ◽  
Hadronic Production ◽  
Current Experimental Data ◽  
Theoretical Results

The associate KΛ(1520) photon and hadronic production in the γp → K+Λ(1520), pp → pK+Λ(1520) and π-p → K0Λ(1520) reactions are investigated within the effective Lagrangian approach and the isobar model. We are interested in the contribution from the N*(2120) (previously called N*(2080)) resonance, which has a significant coupling to the KΛ(1520) channel. The theoretical results show that the current experimental data for the γp → K+Λ(1520) reaction favor the existence of the N*(2120) resonance, and that these measurements can be used to further constrain its properties. We present results, including the N*(2120) contribution, for total cross sections of the γp → K+Λ(1520), π-p → K0Λ(1520), and pp → pK+Λ(1520) reactions. For this latter one, we also calculate invariant mass and Dalitz plot distributions.

Gaseous and surface reactions involving helium metastable atoms and resonance photons

1957 ◽  
Vol 241 (1225) ◽  
pp. 270-282 ◽  
Keyword(s):  
Cross Sections ◽  
Gold Surface ◽  
Target Atom ◽  
Photon Flux ◽  
Total Cross Sections ◽  
Metastable Helium ◽  
Helium Atoms ◽  
Atom Flux ◽  
Collision Chamber ◽  
Argon Ions

The absolute electron yield ( γ M ) for He (2 3 S ) metastable atoms incident on a gold surface has been measured. The method requires passage of a metastable atom flux through a collision chamber containing argon and thence to the gold surface. From observations on the current of argon ions arising from collisions of the type He (2 3 S ) + A → He + A + + e , together with measurements of the electron emission from the gold surface, γ M may be determined. The total cross-sections for collisions between metastable helium atoms and He, Ne, A and K have been measured and in the asymmetrical cases are observed to rise linearly with increasing atomic number of the target atom. Some collisions involving helium resonance radiation have also been studied. In particular, the photo-electric yield from the gold surface has been determined together with the attenuation of the photon flux in passage through certain noble gases.

Total cross sections for charge transfer between Alkali Atoms and Halogen Molecules

1969 ◽  
Vol 3 (7) ◽  
pp. 530-531 ◽  
Author(s):  
A.P.M. Baede ◽  
A.M.C. Moutinho ◽  
A.E. de Vries ◽  
J. Los
Keyword(s):  
Charge Transfer ◽  
Cross Sections ◽  
Total Cross Sections ◽  
Alkali Atoms

scholarly journals Вероятность процессов захвата электронов у атомов аргона ионами -=SUP=-3-=/SUP=-Не-=SUP=-2+-=/SUP=- при различных параметрах удара

2019 ◽  
Vol 89 (3) ◽  
pp. 342
Author(s):  
А.А. Басалаев ◽  
М.Н. Панов
Keyword(s):  
Cross Sections ◽  
Particle Interaction ◽  
Target Atom ◽  
Interaction Potentials ◽  
Atomic Particle ◽  
Total Cross Sections ◽  
Singly Charged ◽  
Scattering Cross Sections ◽  
The Impact ◽  
Argon Ion

AbstractWe have measured the absolute values of total cross sections of capture of one and two electrons by He^2+ ions from argon atoms. The differential scattering cross sections have been determined for fast atoms and singly charged helium ions formed in each of these processes (without and with additional ionization of the formed slow argon ion). Measurements have been taken for He^2+ ions with kinetic energy of 6 keV in scattering angle range 0–2.5°. Based on the measured differential cross sections using different model atomic particle interaction potentials, we have calculated the cross sections of these processes as functions of the impact parameter. The probabilities of realization of these processes with electron density distribution in different shells in the target atom have been compared. The applicability of the expressions for the screened Coulomb interaction potentials in the description of scattering of particles that have captured electrons has been demonstrated.

Sign in / Sign up

Export Citation Format

Share Document