Double ionization of helium by slow antiprotons

Abstract

Coupled-states calculations with large target-centred basis sets have been used to compute ionization probabilities and cross sections for at collision energies down to 10 keV. The results are in good agreement with recent theoretical calculations based on numerical solution of the time-dependent Schrödinger equation but there are no experimental data. Both an independent particle model and an independent event model were used to carry out calculations for . These results are in good agreement with experiment at 40 keV and above but differ at lower energies. The impact-parameter-dependent probabilities for these collisions were used in the independent event model to calculate helium double-ionization cross sections and excellent agreement was found with experimental measurements between 13 and 200 keV, but this simple way of treating correlation fails at higher collision energies.

Ionization of water molecules by proton impact: Two nonperturbative studies of the electron-emission spectra

“…4. The ionization probabilities of the many-electron system are obtained from the one-electron ionization probabilities using the independent event model (IEVM) (see Ref [25]). In practice (see [10]), the two electrons occupying the same MO can be simultaneously ejected, while the probability of ejecting two electrons from different shells is neglected.…”

Classical treatment of ion-H2O collisions with a three-center model potential

“…[33] and used in several works (e.g., [34][35][36]) for ion collisions with He. Following the interpretation of Janev et al [34], the IEVM assumes that the many-electron removal takes place sequentially.…”

“…In this respect, it is noteworthy that relevant anisotropy effects have been detected in calculations of both H + -and e-H 2 O collisions (see, e.g., [26,32]). The evaluation of inelastic probabilities for the physical many-electron system, in terms of the monoelectronic ones resulting from the model potential calculations, is performed by means of the independent-event model (IEVM) [33][34][35][36], which has been found [31,37] to be more adequate than the usual IPM for multielectronic targets.…”

Lattice description of electron loss in high-energy H++H2O collisions

“…In particular, electron capture and ionization cross sections have been calculated by applying the first Born approximation [3], the continuumdistorted-wave method [4,5,6,7,8,9,10], the classical trajectory Monte Carlo (CTMC) [11,12,13,14] and the semiclassical treatment with pseudostates [15,16,17,18]. The one-electron probabilities yielded by these calculations are then combined (see [19,20]) to obtain the probabilities for the many-electron processes. For instance, the electron production probability P EP , in ion collisions with H 2 O is given by the simple relationship [21]:…”