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Distorted wave models are employed to investigate the electron loss process induced by bare ions on biological targets. The two main reactions which contribute to this process, namely, the single electron ionization as well as the single electron capture are here studied. In order to further assess the validity of the theoretical descriptions used, the influence of particular mechanisms are studied, like dynamic screening for the case of electron ionization and energy deposition on the target by the impacting projectile for the electron capture one. Results are compared with existing experimental data. [ABSTRACT FROM AUTHOR]

The triple-differential cross section (TDCS) for the (e, 2e) ionization of a hydrogen molecule is calculated using the molecule distorted-wave Born approximation (MDWBA). Distorted waves are obtained by solving momentum-space coupled-channel Lippmann--Schwinger equations, including the ground state and the lowest-lying electronic state of b³∑u. TDCSs at the incident energy 100 eV in coplanar asymmetric geometry are reported. The present calculations are compared with the available experimental measurements and the theoretical results. [ABSTRACT FROM AUTHOR]

As a fundamental test for state-of-the-art theoretical approaches, we have studied the single ionization (2p) of neon at a projectile energy of 100 eV. The experimental data were acquired using an advanced reaction microscope that benefits from high efficiency and a large solid-angle acceptance of almost 4p. We put special emphasis on the ability to measure internormalized triple-differential cross sections over a large part of the phase space. The data are compared to predictions from a second-order hybrid distorted-wave plus R-matrix model and a fully nonperturbative B-spline R-matrix (BSR) with pseudostates approach. For a target of this complexity and the low-energy regime, unprecedented agreement between experiment and the BSR model is found. This represents a significant step forward in the investigation of complex targets. [ABSTRACT FROM AUTHOR]

A four-body distorted-wave approximation is applied for theoretical analysis of the fully differential cross sections (FDCS) for proton-impact single ionization of helium atoms in their ground states. The nine-dimensional integrals for the partial amplitudes are analytically reduced to closed-form expressions or some one-dimensional integrals which can be easily calculated numerically. Calculations are performed in the scattering and perpendicular planes. The influence of the target static electron correlations on the process is investigated using a number of different bound-state wave functions for the ground state of the helium targets. An illustrative computation is performed for 75-keV proton-helium collisions and the obtained results are compared with experimental data and other theoretical predictions. Although for small momentum transfers, the comparison shows a reasonable agreement with experiments in the scattering and perpendicular planes, some significant discrepancies are still present at large momentum transfers in these planes. However, our results are compatible and for some cases, better than those of the other sophisticated calculations. [ABSTRACT FROM AUTHOR]

We have performed a kinematically complete experiment on ionization of H2 by 75 keV proton impact. The triple differential cross sections (TDCS) extracted from the measurement were compared to a molecular 3-body distorted wave (M3DW) calculation for three different electron ejection geometries. Overall, the agreement between experiment and theory is better than in the case of a helium target for the same projectile. Nevertheless, significant quantitative discrepancies remain, which probably result from the capture channel, which may be strongly coupled to the ionization channel. Therefore, improved agreement could be expected from a non-perturbative coupled-channel approach. [ABSTRACT FROM AUTHOR]

We have measured cross sections for the ionization of the K shell by electrons with energies from the respective thresholds up to 100 keV, for Au and Bi. The experimental values are obtained by dividing the number of counts in the Kα peak by the number of counts in an energy interval near the tip of the bremsstrahlung continuum, and multiplying this ratio by the theoretical estimate of bremsstrahlung emission towards the detector in this energy interval. Although such a procedure has already been described in the literature, here it is implemented avoiding some of the simplifications made in earlier works. Our experimental cross sections, which are the first ones to be reported for atoms with close to the threshold, are in reasonable agreement with the theoretical predictions of the semirelativistic distorted-wave Born approximation. Hipplerʼs plane-wave Born approximation with corrections for Coulomb and exchange effects yields cross sections that are closer to the experimental data than those evaluated from the relativistic binary-encounter-Bethe model. [ABSTRACT FROM AUTHOR]