2 research outputs found
Electron impact double ionization of helium from classical trajectory calculations
With a recently proposed quasiclassical ansatz [Geyer and Rost, J. Phys. B 35
(2002) 1479] it is possible to perform classical trajectory ionization
calculations on many electron targets. The autoionization of the target is
prevented by a M\o{}ller type backward--forward propagation scheme and allows
to consider all interactions between all particles without additional
stabilization. The application of the quasiclassical ansatz for helium targets
is explained and total and partially differential cross sections for electron
impact double ionization are calculated. In the high energy regime the
classical description fails to describe the dominant TS1 process, which leads
to big deviations, whereas for low energies the total cross section is
reproduced well. Differential cross sections calculated at 250 eV await their
experimental confirmation.Comment: LaTeX, 22 pages, 10 figures, submitted to J. Phys.
Recommended from our members
On the Significance of the Contribution of Multiple-Electron Capture Processes to Cometary X-Ray Emission
We report laboratory studies of the role played by multiple-electron capture (MEC) in solar wind induced cometary X-ray emission. Collisions of Ne{sup 10+} with He, Ne, Ar, CO, and CO{sub 2} have been investigated by means of the traditional singles X-ray spectroscopy in addition to the triple-coincidence measurements of X-rays, scattered projectile, and target recoil ions for the atomic targets. The coincidence measurements enable the reduction of the singles X-ray spectra into partial spectra originating in single-electron capture (SEC) and MEC collisions. The measurements provide unequivocal evidence for a significant role played by MEC, and strongly suggest that models based solely on SEC are bound to yield erroneous conclusions on the solar wind composition and velocities and on cometary atmospheres. The experimental relative importance of MEC collisions is compared with molecular classical-over-the-barrier model (MCBM), classical trajectory Monte Carlo (CTMC), and multi-channel Landau-Zener (MCLZ), calculations which can qualitatively reproduce the experimental trends