Single and double electron removal from helium by protons

Abstract

The independent event model (IEV) is used to calculate single and double electron removal cross sections for p + + He collisions. The single electron removal cross sections are in good agreement with experiment. In contrast to the model of Janev and co-workers, it is found that the single electron removal cross section for p + + He + is much larger than the double electron removal cross section for p + + He, since in small impact parameter collisions of protons with He the probability of removing the first electron is less than unity. Double electron removal cross sections for p + + He calculated in the IEV are found to be in poor agreement with experiment, in contrast to p − + He where good agreement was obtained. For p + + He, the IEV double ionization result is improved somewhat if approximate allowance is made for the screening of the projectile by the electron if it is captured in the first event. The difference in the agreement of the IEV double ionization results with experiment may also indicate a qualitative difference in the role played by electron correlation in these two collision systems.

Multi-cut forced impulse method single-ionization cross sections for slow antiprotons on helium

“…This new failed attempt, taken together with our previous study of hydrogen targets (Hall et al 1996), establishes that antiproton single-ionization cross sections at low energies for both hydrogen and helium targets cannot be reproduced by our finite Hilbert basis set (FHBS) calculations. Here we expand the system wavefunction in a single-centred set of square-integrable functions, localized around the target.…”

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

“…In this respect, we have found, taking experimental data on H + + H 2 O collisions as references, that both single-and double-electron processes are better described by our implementation of the IEVM (see, however, [36,43]). The probabilities for transfer ionization (TI), double ionization (DI), and double capture (DC) are obtained following arguments similar to those leading to (8):…”

Multi-ionization of helium and lithium using the independent electron and independent event models with intrinsic CDW

“…Cross sections are presented for the DI of He (see figures 1 and 2) and Li (see figures 3 and 4) with H + and He 2+ as the projectiles, and finally figure 5 shows the cross section for the collision of He with Li 3+ . These collisions have been chosen due to the wealth of experimental data (see [10][11][12]) available, and the existence of independent theoretical predictions from Ford et al [13], which this discussion expands upon, considering however a wider variety of targets and projectiles. Attention is mainly focused on the CDS models for two reasons.…”