Application of the JJ-matrix Method to Faddeev-Merkuriev equation: beyond pseudostates

A version of the $J$-matrix method for solving numerically the three-body Faddeev-Merkuriev differential equations is proposed. This version allows to take into account the full spectrum of the two-body Coulomb subsystem. As a result, a discrete analog of the Lippmann-Schwinger equation is obtained which allows to interpret correctly the three-body wave function in two-body domains. The scheme is applied to calculations of the fully resolved absolute differential cross sections for the He$(e,2e)$He$^+$ and He$(e,3e)$He$^{++}$ reactions at small energy and momentum transfers. The results are in good agreement with the experiment both in shape and in absolute value.Comment: 22 pages, 7 figure

Coincidence Angular Correlation in Electron Impact Single or Double Ionisation of Atoms and Molecules

Experimental results obtained with our multi-parameter multi-coincidence spectrometer are presented for the (e,3e) double ionisation of Ar and (e,2e) single ionisation of small molecules. The (e,3e) measurements are discussed in terms of competition between the two double ionisation processes present under the chosen kinematics, and qualitative conclusions are given. The results for the ionisation of H2 and the outer orbital of N2 are compared with the predictions of the most elaborate available theoretical models for description of the molecular ionisation process. Overall reasonable agreement is observed and tentative interpretations for the discrepancies are discussed

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.

Comparative study of argon 3p electron-impact ionization at low energies

(c) 2001 The American Physical SocietyAn experimental and theoretical study of electron-impact ionization of the 3p orbital in argon is presented. The (e,2e) technique was used to measure the relative triple-differential cross section for this process in the coplanar asymmetric geometry. The experimental results were obtained at an incident electron energy of 113.5 eV, a scattering angle of 15°, and ejected electron energies of 10, 7.5, 5, and 2 eV. The experimental data are compared with a distorted-wave Born approximation (DWBA) calculation, and also with previous results for argon 3s ionization obtained under identical kinematic conditions. Discrepancies between the experimental and theoretical data are attributed to the effects of charge-cloud polarization and higher-order scattering processes, which are not incorporated in the DWBA calculation.Haynes, Matthew A. and Lohmann, Birgi