An adaptive classical trajectory Monte Carlo model that explicitly considers the eight electrons corresponding to the valence molecular orbitals of the H2O molecule is introduced. In this dynamical model, the electrons' binding energies change throughout the collision ensuring the proper energy deposition by the projectile for multiple electron removal. Present results are relevant to the ion-therapy program, specially at irradiation planning stages in which detailed information on the electronic emission spectra are needed as input data.

A classical trajectory Monte Carlo model that explicitly considers the ten electrons of the H2O molecule is used to study electron production in collisions involving bare ions. Present results are contrasted to the reported experimental data and to other theoretical results obtained by means of distorted wave models. Focus is made on the energy range 100 (keV/amu) /ZP-1000 (keV/amu)/ZP along which a simple scaling for the net cross section is introduced.

In this work, collision processes between C6+, O8+ and Si13+ ions and H2O molecules that lead to target ionization are studied by means of the classical trajectory Monte Carlo method. We employ an 8-electron model in which the H2O electron densities and energies dynamically adapt during ionization processes to those corresponding to the H2Oq+ ions by assuming vertical transitions between the different molecular ionic states. Net total ionization cross sections and single differential cross sections in energy and angle are shown for 4 MeV/u projectiles and compared to available experimental data and theoretical predictions from distorted wave models.

Collisional ionization processes involving H2O molecules and C6+, O8+, Si13+ ions are studied by means of the classical trajectory Monte Carlo method using molecular orbital calculations to define the ionization stages of the water molecule. Net total and single-differential cross sections in energy and angle are obtained by using a newly developed model that goes beyond the commonly applied one-active electron approximation. This model allows us to access the fraction of electron emission arising from single and multiple electron ionization. Calculated cross sections are contrasted and benchmarked against available experimental data at impact energies in the MeV/u range. The present results highlight the important role of multiple ionization in the emission of electrons where we find the majority of electrons emitted with energies greater than ~50 eV arise from multiple ionization collisions.

In this work the single-electron capture and single-ionization processes are studied for proton collisions with He and Ar atoms at impact energies in the range 25-100 keV. Classical trajectory Monte Carlo simulations are benchmarked against experimental data obtained at the reaction microscope in Bariloche, Argentina, which employs the cold target recoil-ion momentum spectroscopy technique. Special emphasis is placed on describing the momentum transfer to the recoil ion for these collision systems.

In this work we theoretically study photonic spectra that follow charge exchange processes between highly charged ions and neutral argon and CO targets. The range of collision energies studied is 5 eV/amu-10 keV/amu, covering typical EBIT-traps and Solar Wind energies. Our studies are based on multiple electrons schemes within the classical trajectory Monte Carlo method. Electrons are sorted with the sequential binding energies for the target under consideration. The role played by the multiple electron capture process for the different collision systems under consideration is explicitly analyzed and its contribution separated as arising from double radiative decay and autoionizing multiple capture. Present studies are stimulated by the upcoming launch of the Astro-H mission in 2015, which will provide high resolution spectra in the 0.3 keV-12keV band.

Fil: Cariatore, Nelson Daniel. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Bahia Blanca. Instituto de Fisica del Sur. Universidad Nacional del Sur. Departamento de Fisica. Instituto de Fisica del Sur; Argentina

In this work we use the classical trajectory Monte Carlo method within an eight-electron scheme to theoretically study photonic spectra that follow charge-exchange processes between highly charged ions of charge states 10+, 17+, 18+, and 36+ with neutral argon. The energy range considered is 18 eV/amu to 4 keV/amu, covering typical electron beam ion traps and solar wind energies. The role played by multiple electron capture processes for the different collision systems under consideration is explicitly analyzed and its contribution separated as arising from radiative decay and autoionizing multiple capture. For the present collision systems we find that multiple electron capture is responsible for 50%-60% of the resulting x-ray spectra. The present results are of direct relevance to the astrophysical program.

The role of electron saddle swaps in collisions of bare Li with metastable hydrogen and alkali-metal atoms is investigated by means of the classical trajectory Monte Carlo method. In particular, we show that oscillations as a function of collision energy in the photon spectra resulting from charge exchange are directly related to the number of potential-saddle crossings that a receding electron can achieve during a given reaction. The range of impact energies spanned is 0.01-50 keV/amu, an area of interest for diagnostic purposes in tokamak nuclear fusion power reactors.

In this work, we present theoretical line emission cross sections for Ar18+ and Ne10+ colliding on Ar for impact energies in the range 5 eV/amu-10 keV/amu which covers typical EBIT-traps as well as Solar Wind energies. The present analysis is performed by means of a 5-body classical trajectory Monte Carlo (CTMC) model which allows us to model the multiple capture contribution to the X-ray line emission spectra. Our results are contrasted to recent capture and line emission data from Berlin-EBIT, NIST and the University of Nevada Reno.

In this work, we have performed an experimental/theoretical study of state selective charge exchange cross sections in 1-10 keV/amu Ne8+ + Na(3s) collisions. Theoretical calculations provided by the classical trajectory Monte Carlo method (CTMC) are contrasted to data obtained at KVI by means of the magneto-optical trap recoil-ion momentum spectroscopy technique (MOTRIMS). We find that for electron capture to n * 10, a two-step mechanism which involves an initial electronic excitation followed by electron capture at a later stage of the collision applies. Oscillatory structures in the n-state selective capture cross sections and recoil ion transverse momentum distributions are present in the experimental data as well as in the theoretical results, and are ascribed to the number of swaps the electron undergoes across the potential energy saddle during the collision process.

We present a systematic experimental and theoretical study of angular differential cross sections of single-electron transfer in collisions of N5+, O6+, and Ne8+ with ground-state Na(3s) in the collision energy range from 1 to 8 keV/amu. Experiments were performed using recoil-ion momentum spectroscopy in combination with a magneto-optically cooled Na atom target. The results are compared with three-body classical-trajectory Monte Carlo theory. Experimental and theoretical angular differential cross sections for capture into highly excited states show an oscillatory structure which is linked to the number of times the active electron crosses the potential energy saddle, i.e., oscillates between the two nuclear centers during the collision process. DOI: 10.1103/PhysRevA.87.032712

Single electron transfer and ionization in collisions of N5+ and Ne8+ with ground state Na(3s) and laser excited Na*(3p) are investigated both experimentally and theoretically at collision energies from 1 to 10 keV/amu, which includes the classical orbital velocity of the valence electron. State-selective partial cross sections are obtained using recoil-ion momentum spectroscopy in combination with a magneto-optically cooled Na atom target. A strong dependence of the cross sections on the collision energy is observed. In general, both the relative magnitude and the energy dependence are found to be in good agreement with classical-trajectory Monte Carlo calculations.

The introduction of gases like nitrogen or neon for cooling the edge region of magnetically confined fusion plasmas has triggered a renewed interest in state-selective cross sections necessary for plasma diagnostics by means of charge exchange recombination spectroscopy. To improve the quality of spectroscopic data analysis, charge exchange and ionization cross sections for N7+ + H(n = 1, 2) have been calculated using two different theoretical approaches, namely the atomic-orbital close-coupling method and the classical trajectory Monte Carlo method. Total and state-resolved charge exchange cross sections are presented in detail. In the second part, we compare two collision systems involving equally charged ions, C6+ and N6+ on atomic hydrogen. The analysis of the data leads to the conclusion that deviations between these two impurity ions are practically negligible. This finding is very helpful when calculating cross sections for collision systems with heavier not completely stripped impurity ions.

State selective charge exchange processes in 1–10 keV/amu Ne8+ +Na(3s) collisions were measured by means of the magneto-optical trap recoil-ion momentum spectroscopy technique and compared to classical trajectory Monte Carlo calculations. We find that for electron capture to n-levels ≥ 10, the transverse momentum distributions exhibit an oscillatory structure which is very sensitive to the impact energy. Our theoretical analysis suggests that this feature is a direct consequence of the number of swaps the electron undergoes across the potential energy saddle during the charge exchange process.

Single electron transfer and ionization in collisions of He-like ions (N5+, O6+, Ne8+) and Na has been investigated both experimentally and theoretically at energies around the matching velocity of the valence electron (2 to 10 keV/amu). State selective cross sections and scattering angle distributions were obtained using recoil-ion momentum spectroscopy in combination with a magneto-optically cooled Na atom target. A strong dependence of the relative cross sections on the collision energy is observed. The results are compared with Classical-Trajectory Monte Carlo (CTMC) calculations and show an overall very good agreement.

Line emission and charge exchange cross sections obtained from a three-active electrons CTMC code allow us to determine the role of multiple electron capture for charge exchange collisions on neutral argon and neon. The present results can be compared to recent experimental data from EBIT groups operating at Liver-more, NIST and Berlin.

State selective single charge exchange n‐level cross sections are calculated for collisions of Xe18+ and Xe54+ ions with Na(3s) and Na*(3p) over the energy range of 0.1 to 10.0 keV/amu. The CTMC method is used which includes all two‐body interactions. Experimental state‐selective cross sections and their corresponding transverse momentum spectra for Xe18+ are found to be in reasonable accord with the calculations.

X-ray emission originating in charge-exchange collisions between Ar18+ and neutral argon is studied at impact energies of 5-4000 eV/amu by means of the classical trajectory Monte Carlo method (CTMC). Line emission and charge-exchange cross sections obtained from different CTMC versions based on the one-active electron approximation are contrasted among themselves and against the results obtained by means of a three-active electron code that lets us infer the role of multiple electron capture. The present results are compared to the recent experimental data available from the EBIT groups operating at Livermore, NIST, and Berlin. We were not able to reconcile the major difference in x-ray emission cross sections obtained from in situ measurements made in EBIT, versus those made in an exterior, field-free collision chamber using ions extracted from the EBIT. Our calculations support the extracted beam results.

Triply differential single ionization of Ar by 200 eV positron and electron impact is measured and calculated. For an unequivocal test of kinematic differences, fully differential ejected electron angular distributions are measured using the same experimental apparatus and conditions for both positron and electron impact. The binary/recoil intensity ratios are shown to significantly differ for the two projectiles. These data are used to test theoretical calculations.