Dispersion relations and the elastic scattering of electrons by helium atoms

1966 ◽  
Vol 294 (1437) ◽  
pp. 149-159 ◽  
Keyword(s):  
Dispersion Relation ◽  
Elastic Scattering ◽  
Cross Sections ◽  
Scattering Length ◽  
Excitation Threshold ◽  
Zero Energy ◽  
Total Cross Sections ◽  
Scattering Angle ◽  
Helium Atoms ◽  
Microwave Probe

The elastic scattering of electrons by helium is analysed in terms of a dispersion relation for the forward scattering intensity. The zero energy scattering length obtained from this relation agrees well with that derived from application of effective range formulae to observed data on total cross sections and to drift velocity and microwave probe data. It also agrees well with results of exchange-adiabatic calculations. At energies below the excitation threshold these calculations give total and differential cross sections which agree well with observed results except at small scattering angles at energies of 10 eV and below. The dispersion relation gives results agreeing with the calculated at zero scattering angle suggesting that the observed distributions are in error. At energies above the excitation threshold the dispersion relation shows that Born’s first approximation is still considerably in error (by a factor of 2) at zero scattering angle at energies of 300 eV. Experimental data between 100 and 300 eV are consistent with extrapolation to the values given by the dispersion relation for the forward scattered intensity.

SCATTERING AND DISSOCIATION OF DEUTERONS AND 3H-NUCLEI BY NUCLEI AT INTERMEDIATE ENERGIES

1995 ◽  
Vol 04 (03) ◽  
pp. 563-586 ◽  
Author(s):  
YU. A. BEREZHNOY ◽  
V. YU. KORDA
Keyword(s):  
Elastic Scattering ◽  
Closed Form ◽  
Cross Sections ◽  
Differential Cross ◽  
Particle System ◽  
Center Of Mass ◽  
Scattering Angle ◽  
Intermediate Energies ◽  
Oscillating Functions ◽  
Analytical Expressions

We present a closed-form description that enables us to obtain the analytical expressions for the elastic scattering and dissociation differential cross-sections of deuterons and 3H-nuclei by heavy target nuclei. The resulting expressions are used to analyze the data for the 110 MeV deuterons elastically scattered on 208Pb-nuclei. The dissociation cross-sections of deuterons and 3H-nuclei are the oscillating functions of the scattering angle of the released two- and three-nucleon-particle system center-of-mass.

Pseudopotential calculations of elastic scattering of electrons by helium atoms in the range 0–20 eV

1990 ◽  
Vol 68 (1) ◽  
pp. 104-110 ◽  
Author(s):  
B. Plenkiewicz ◽  
P. Plenkiewicz ◽  
J.-P. Jay-Gerin
Keyword(s):  
Experimental Data ◽  
Elastic Scattering ◽  
Momentum Transfer ◽  
Cross Sections ◽  
Theoretical Calculations ◽  
Incident Electron ◽  
Elastic Electron ◽  
Scattering System ◽  
Helium Atoms ◽  
Pseudopotential Calculations

Our earlier pseudopotential calculations on electrons colliding with argon and krypton are extended to consider the elastic electron–helium scattering system. In this paper, we present detailed results for phase shifts, differential, total, and momentum-transfer cross sections for this system for incident electron energies in the range from 0 to 20 eV. These agree very well with existing experimental data and with other theoretical calculations.

The elastic scattering of fast electrons and positrons by hydrogen and helium atoms

1959 ◽  
Vol 250 (1262) ◽  
pp. 337-345 ◽  
Keyword(s):  
Elastic Scattering ◽  
Cross Sections ◽  
Differential Cross ◽  
Born Approximation ◽  
Logarithmic Singularity ◽  
Hydrogen Atoms ◽  
Fast Electrons ◽  
Helium Atoms ◽  
Electrons And Positrons ◽  
Angle Scattering

A simplification of the second Born approximation due to Massey & Mohr is used to calculate the differential cross-sections for the elastic scattering of fast electrons and fast positrons by hydrogen atoms and helium atoms, the method of Dalitz being applied to evaluate all the relevant integrals. Although the logarithmic singularity which is found in the differential cross-section for zero-angle scattering is shown to be absent in the true second Born approximation the use of the simplification of this approximation is justified at sufficiently high impact energies provided the angle of scattering is not too small. The results of the calculations for incident electrons in helium are compared with the available experimental data.

Elastic Scattering of Electrons by Helium Atoms at Intermediate Energies

1993 ◽  
Vol 48 (3) ◽  
pp. 465-468
Author(s):  
V. M. Chhaya ◽  
J. J. Tarwadi ◽  
Smita Chhag
Keyword(s):  
Elastic Scattering ◽  
Energy Range ◽  
Cross Sections ◽  
Differential Cross ◽  
Hydrogen Atoms ◽  
Helium Atoms ◽  
Intermediate Energies ◽  
Born Series ◽  
Electrons And Positrons ◽  
Theoretical Results

Abstract The unitarised Eikonal Born series (UEBS) method has been used successfully by Byron et al. for elastic scattering of electrons and positrons by hydrogen atoms. Here an attempt is made to apply the UEBS method in the case of elastic scattering of electrons by helium atoms. The total and differential cross sections are calculated for the energy range 100-700 eV. The results are compared with experimental and other theoretical results. It is found that the results obtained with the UEBS method agree best with the experimental results.

STUDY OF MESON PRODUCTION IN NUCLEI NEAR THRESHOLD

2009 ◽  
Vol 18 (05n06) ◽  
pp. 1271-1281 ◽  
Author(s):  
B. K. JAIN ◽  
N. J. UPADHYAY ◽  
K. P. KHEMCHANDANI ◽  
N. G. KELKAR
Keyword(s):  
Cross Sections ◽  
Final State Interaction ◽  
Scattering Length ◽  
Meson Production ◽  
Final State ◽  
Total Cross Sections ◽  
Low Energies ◽  
Final State Interactions ◽  
T Matrix ◽  
Near Threshold

We present a study of the η production at low energies in pd collision with 3He and pd nuclear systems in the final state. The η production mechanism is described by a two-step model and the final state interactions are included fully. The η - d and η - 3He final state interactions are incorporated through the solution of the Lippmann Schwinger equation for a half off-shell η - AT-matrix. For η - d this t -matrix is written in a factorized form, with an off-shell form factor multiplying an on-shell part having the scattering length representation. The p - d final state interaction is included by multiplying the production matrix element by the inverse of the Jost function which includes the strong as well as the Coulomb interaction. The total cross sections are found to be strongly affected by both the η - d and the p - d final state interactions. The η - 3HeT-matrix is obtained in the Finite Rank Approximation (FRA) by solving few-body equations. The calculated total cross sections are in good accord with the available experimental data. Through the time delay method of Wigner, we also explore the possibility of the existence of quasi-bound η-3 He mesic states in this η - 3He T -matrix. We find that the T -matrix which reproduces the low energy pd → 3He η data implies a quasi-bound eta state near threshold. This is in accord with experimental indications.

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.

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