No abstract available

[en] The triple differential cross section for electron impact ionisation of He is measured in 'energy-sharing' and 'non-coplanar symmetric' kinematics. Experiments performed at 424.5 eV incident energy and at different scattering angles are reported. The present experimental results are compared with the eikonal distorted-wave impulse approximation. They give further evidence for the inadequacy of this approximation at small scattering angles. (author)

[en] Impulsive (e,2e) reactions on atoms are briefly introduced, and results obtained on Ne, Ar, and Kr are summarized and compared with similar photoelectron data. It is seen that the intensities of satellite peaks obtained at large or small momentum transfers are different. An attempt is made to give a unified treatment of all the satellite structure

No abstract available

[en] The He II n=2 satellite in the He ionisation spectrum is investigated by measuring the angular dependence of the (e, 2e) triple differential cross section (TDCS) in asymmetric geometry for the first time, at moderate momentum transfer (0.8 a₀^-1) and low ejected electron energy (20 eV). The generalised oscillator strengths for the transitions to the n=1 and n=2 He II states are derived from the TDCS and their ratio is in fair agreement with a recent close coupling calculation. The experimental angular distribution of the n=2 TDCS shows peculiarities, typical of continuum final-state correlations, which appear to be much more relevant when the final ionic state is the excited one. (author)

[en] Results of an extensive set of measurement of (e,2e) reactions on noble gases are reported, along with a concise description of the experimental set-up. Some conclusions are drawn on the conditions in which the (e,2e) reaction is a valuable tool to investigate atomic wave functions

[en] This Comment attempts to survey the status of (e, 2e) experiments, confining attention to those for which the impulse approximation can be satisfactory applied. The experimental conditions for which this coincidence technique gives unambiguous information on the electronic structure of atoms and molecules are discussed. Future developments are briefly considered. (author)

[en] This paper reports on an approach to the triple differential cross section calculation which maintains the exact factorization of the Plane Wave Impulsive 1Approximation (PWIA) and accounts for the long range Coulomb interactions amonth the three finall charged particles in a semiclassical way. The pure PWIA model has been improved through a simple correction to include the long range tails of the Coulomb interaction between the final electrons. This model has given satisfactory predictions for a large part of the existing body of (e,2e) experimental data on He, both for symmetric and not extremely asymmetric reactions and for inciO dent energy as low as 200 eV

[en] Information on ionization theories obtainable in dypole and binary (e,2e) experiments is discussed. Some data taken in asymmetric kinematics on He are presented. (Auth.)

[en] The approximation of local translational invariance is necessary to produce a tractable effective interaction between two particles in a many-body system. This approximation is tested for the (e,2e) reaction by testing the shell-averaged eikonal approximation in which particles propagate in a constant average potential anti V, which is shown to depend on the recoil momentum. In this approximation the distorted-wave impulse approximation factorises into parts depending on the structure and the two-body interaction. Experiments are reported for neon in which the structure factor is kept constant in order to provide a test of the reaction theory. The incident energies are 800 eV and 1600 eV. The q-dependent eikonal approximation works well over a large kinematic range but not for small values of the angle between the outgoing electrons, or for q near the maximum in the 2p cross section at the lower energy. Factorised calculations with fully evaluated optical-model distorted waves do not always work as well as the eikonal approximation. (author)