scholarly journals The Momentum Transfer Cross Section for Electrons in Helium Derived from Drift Velocities at 77°K

1970 ◽  
Vol 23 (5) ◽  
pp. 667 ◽  
Author(s):  
RW Crompton ◽  
MT Elford ◽  
AG Robertson
Keyword(s):  
Energy Range ◽  
Momentum Transfer ◽  
Cross Section ◽  
Scattering Length ◽  
Direct Determination ◽  
A Value ◽  
Energy Dependent ◽  
Momentum Transfer Cross Section

Drift velocities of electrons in helium at 76.8�K have been measured for 8 X lO−20 ≤ E/N ≤ 2 X lO−17 V cm2. From these data, and the earlier measurements of Crompton, Elford, and Jory made at 293�K, the energy-dependent momentum transfer cross section has been determined for electrons with energies between 0.008 and 6 eV. The present cross section agrees with that of Crompton, Elford, and Jory to within 1 %. The extension of the energy range to 8 meV permits a direct determination of the scattering length, for which a value of 1.19 ao is obtained.

scholarly journals The Momentum Transfer Cross Section for Electrons in Helium

1967 ◽  
Vol 20 (4) ◽  
pp. 369 ◽  
Author(s):  
RW Crompton ◽  
MT Elford ◽  
RL Jory
Keyword(s):  
Energy Range ◽  
Momentum Transfer ◽  
Cross Section ◽  
Drift Velocity ◽  
Low Energy ◽  
Theoretical Cross Section ◽  
Velocity Data ◽  
The Cross ◽  
Energy Dependent ◽  
Momentum Transfer Cross Section

Measurements of the drift velocity, the ratio of diffusion coefficient to mobility, and the "magnetic drift velocity" for electrons in helium have been made at 293�K in the range 1.8 X 10−19 E/N −17 V cm2. From an analysis of the drift velocity data, an energy-dependent momentum transfer cross section has been derived for which an error of less than � 2 % is claimed over the central portion of the energy range. The cross section agrees with the theoretical cross section of La Bahn and Callaway to within 2% over the whole energy range. The agreement with the cross section derived by a number of procedures from the total elastic scattering cross section measured by Golden and Bandel is less satisfactory. The drift data are sufficiently accurate to enable a search to be made for the effects of fine structure in the cross section at low energy. The results do not support the existence of such structure.

scholarly journals Energy-dependent Ps-He momentum-transfer cross section at low energies

2008 ◽  
Vol 77 (1) ◽  
Author(s):  
J. J. Engbrecht ◽  
M. J. Erickson ◽  
C. P. Johnson ◽  
A. J. Kolan ◽  
A. E. Legard ◽  
...  
Keyword(s):  
Momentum Transfer ◽  
Cross Section ◽  
Low Energies ◽  
Energy Dependent ◽  
Momentum Transfer Cross Section

scholarly journals The Momentum Transfer Cross Section for Electrons in Argon in the Energy Range 0 - 4 eV

1977 ◽  
Vol 30 (1) ◽  
pp. 61 ◽  
Author(s):  
HB Milloy ◽  
RW Crompton ◽  
JA Rees ◽  
AG Robertson
Keyword(s):  
Momentum Transfer ◽  
Cross Section ◽  
Cross Sections ◽  
Scattering Length ◽  
Effective Range ◽  
Fitting Procedure ◽  
Low Energies ◽  
Range Theory ◽  
The Cross ◽  
Momentum Transfer Cross Section

The momentum transfer cross section for electron-argon collisions in the range 0–4 eV has been derived from an analysis of recent measurements of DT/μ as a function of E/N at 294 K (Milloy and Crompton 1977a) and W as a function of E/N at 90 and 293 K (Robertson 1977). Modified effective range theory was used in the fitting procedure at low energies. An investigation of the range of validity of this theory indicated that the scattering length and effective range were uniquely determined ,and hence the cross section could be accurately extrapolated to zero energy. It is concluded that for ε ≤ 0.1 eV the error in !he cross section is less than � 6 % and in the range 0.4 ≤ ε (eV) ≤ 0.4 the error is less than � 8 %. In the range 0.1 < ε (eV) < 0.4 the presence of the minimum makes it difficult to determine the errors in the cross section but it is estimated that they are less than −20 %, +12 %. It is demonstrated that no other reported cross sections are compatible with the experimental results used in the present derivation.

scholarly journals The Momentum Transfer Cross Section for Electrons in Mercury Vapour from 0·1 to 5 eV

1980 ◽  
Vol 33 (2) ◽  
pp. 259 ◽  
Author(s):  
MT Elford
Keyword(s):  
Experimental Data ◽  
Energy Range ◽  
Momentum Transfer ◽  
Cross Section ◽  
Drift Velocity ◽  
Cross Sections ◽  
Mercury Vapour ◽  
Velocity Data ◽  
Maximum Value ◽  
Momentum Transfer Cross Section

The momentum transfer cross section for electrons in mercury vapour has been derived over the energy range 0�1-5 eV from the drift velocity data of Elford (1980). The cross section has a resonance at 0�5 eV with a maximum value of 180 A 2 (1� 8 x 10-18 m2). It is shown that previous cross sections derived either from experimental data or obtained by ab initio calculations are incompatible with the drift velocity data.

scholarly journals Momentum Transfer Cross Section for e??Kr Scattering

1993 ◽  
Vol 46 (2) ◽  
pp. 249 ◽  
Author(s):  
MJ Brennan ◽  
KF Ness
Keyword(s):  
Energy Range ◽  
Momentum Transfer ◽  
Cross Section ◽  
Drift Velocity ◽  
Cross Sections ◽  
Theoretical Calculations ◽  
Transport Coefficients ◽  
Velocity Data ◽  
Experimental Errors ◽  
Momentum Transfer Cross Section

The momentum transfer cross section for electrons in krypton has been derived over the energy range Q-4 eV from an analysis of drift velocity and DT/I-' data for hydrogen-krypton mixtures. At energies in the vicinity of the Ramsauer-Townsend minimum, the present work differs significantly from derivations based on analyses of drift velocity data alone. The overall uncertainty in the derived cross section reflects the experimental errors in the transport coefficients, the uncertainty in the cross sections used to represent the hydrogen component in the mixtures, and the uncertainty associated with the X2 minimisation. The present cross section is compared with recent theoretical calculations and other experimental derivations.

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.

scholarly journals Relativistic Effects in Low-energy Electron - Argon Scattering

1997 ◽  
Vol 50 (3) ◽  
pp. 511 ◽  
Author(s):  
R. P. McEachran ◽  
A. D. Stauffer
Keyword(s):  
Differential Cross Section ◽  
Cross Section ◽  
Differential Cross ◽  
Scattering Length ◽  
Relativistic Effects ◽  
Low Energy ◽  
Relativistic Treatment ◽  
Elastic Differential Cross Section ◽  
Low Energy Electron ◽  
Momentum Transfer Cross Section

We have performed a relativistic treatment at low energy of electron–argon scattering which includes both polarisation and dynamic distortion effects. Our results are in excellent agreement with the experimentally derived momentum transfer cross section and scattering length, as well as with very recent measurements of the elastic differential cross section.

Direct determination of the two-photon absorption cross section by the intracavity laser spectroscopy method

1984 ◽  
Vol 14 (12) ◽  
pp. 1596-1599 ◽  
Author(s):  
V M Baev ◽  
T P Belikova ◽  
V F Gamaliĭ ◽  
E A Sviridenkov ◽  
A F Suchkov
Keyword(s):  
Cross Section ◽  
Absorption Cross Section ◽  
Direct Determination ◽  
Photon Absorption ◽  
Absorption Cross ◽  
Intracavity Laser Spectroscopy ◽  
Two Photon Absorption ◽  
Two Photon ◽  
Intracavity Laser

Momentum-transfer cross section for slow positronium-He scattering

1998 ◽  
Vol 31 (2) ◽  
pp. 329-339 ◽  
Author(s):  
Y Nagashima ◽  
T Hyodo ◽  
K Fujiwara ◽  
A Ichimura
Keyword(s):  
Momentum Transfer ◽  
Cross Section ◽  
Momentum Transfer Cross Section
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