Multiple Capture Contributions In Charge Exchange Induced X-ray Spectra And Their Relevance To Astrophysical Applications

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.Fil: Otranto, Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - CONICET - Bahía Blanca. Instituto de Física del Sur; Argentina. Universidad Nacional del Sur. Departamento de Física; ArgentinaFil: Olson, R. E.. Missouri University of Science and Technology. Physics Department; Estados Unidos de América

Autoionization of He Atoms by Partially Stripped Ion Impact

A study of the autoionization process induced by partially stripped ion impact is performed. Electron spectra in momentum space are predicted within a classical model for partially stripped ions. The results are compared with those obtained for pure Coulomb-like projectiles. A quantum-mechanical extension of the Barrachina-Macek model is proposed for partially stripped projectiles. Structure on the electron angular distribution arising in quantum and classical treatments is identified and compared. The presence of rainbow scattering interference is observed in the binary ring profile of the outgoing autoionized electrons for positive-ion impact

Charge Exchange and X-Ray Emission Cross Sections for Multiply Charged Ions Colliding with H₂O

Total and state selective nl-electron capture cross sections are presented for highly charged ions Z=4-10, 14, 18, and 26 colliding with water molecules. The energy range investigated was from 10 eV/amu (v=0.02 a.u.) to 100 keV/amu (v=2 a.u.). An initialization for the 1B1 and 3A1 orbitals of the water molecule is introduced based on the one center expansion of Moccia and compared to our previous studies based on a hydrogenic approximation within the microcanonical ensemble. The Z dependence of the calculated total cross sections is in reasonable agreement with the recent data of Mawhorter et al. [Phys. Rev. A 75, 032704 (2007)] and is improved over previous results. The energy dependence of the n- and l-level populations is investigated. The K-shell x-ray emission cross sections are determined by using the calculated state-selective electron capture results as input and then applying hydrogenic branching and cascading values for the photon emission. Our results compare favorably with experimental data from the KVI-Groningen, Jet Propulsion Laboratory and Lawrence Livermore National Laboratory groups

Light-Particle Single Ionization of Argon: Influence of the Projectile Charge Sign

The ionization of the 3p orbital of argon by incident electrons and positrons is studied by means of the post version of the continuum distorted wave-eikonal initial-state model. Results are presented at both 200 and 500 eV impact energies for conditions amenable to present experiments. Differences in the fully differential cross sections (FDCSs) are analyzed and the influence of the projectile charge sign on the emission dynamics is discussed. The FDCSs are found to display the classic binary plus recoil peak structure at 500 eV, but transition to a more complicated four-lobed structure at the lower impact energy

Classical description of H ( 1 s ) and H * ( n = 2 ) for cross-section calculations relevant to charge-exchange diagnostics

In this work, we introduce a classical trajectory Monte Carlo (CTMC) methodology, specially conceived to provide a more accurate representation of charge-exchange processes between highly charged ions and H(1s) and H∗ (n = 2). These processes are of particular relevance in power fusion reactor programs, for which chargeexchange spectroscopy has become a useful plasma diagnostics tool. To test the methodology, electron-capture reactions from these targets by C6+, N7+, and O8+ are studied at impact energies in the 10–150 keV/amu range. State-selective cross sections are contrasted with those predicted by the standard microcanonical formulation of the CTMC method, the CTMC method with an energy variation of initial binding energies that produces an improved radial electron density, and the atomic orbital close-coupling method. The present results are found in to be much better agreement with the quantum-mechanical results than the results of former formulations of the CTMC method.Fil: Cariatore, Nelson Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Física del Sur. Universidad Nacional del Sur. Departamento de Física. Instituto de Física del Sur; ArgentinaFil: Otranto, Sebastián. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Física del Sur. Universidad Nacional del Sur. Departamento de Física. Instituto de Física del Sur; ArgentinaFil: Olson, R. E.. University of Missouri; Estados Unido

The Role of Multiple Electron Capture in the X-Ray Emission Process Following Charge Exchange Collisions with Neutral Targets

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

X-Ray Emission Produced in Charge-Exchange Collisions between Highly Charged Ions and Argon: Role of the Multiple Electron Capture

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

Reply to Comment on \u27Classical Description of H(1s) and H* (n=2) for Cross-Section Calculations Relevant to Charge-Exchange Diagnostics\u27

In reply to the Comment of Jorge et al. [Phys. Rev. A 93, 066701 (2016)], we agree and reconfirm that the alternative classical trajectory Monte Carlo method (called hydrogenic-Z-CTMC) radial distributions for H*(n = 2) we recently published are not stable in time. However, we show that such lack of stability which is more noticeable for H(2s) than for H(2p) is due to the initialization procedure employed and not to the hydrogenic-Z-CTMC method itself. A new set of completely stable hydrogenic-Z-CTMC calculations for H*(n = 2) is introduced and found in very good agreement with standard microcanonical results reinforcing our previous findings. A second criticism of Jorge et al. concerning the number of components in hydrogenic-Z-CTMC with n \u3e 1 for H(1s) is shown not to have a significant impact on relative (n,l) populations in the final state

Oscillatory Patterns In Angular Differential Ion-Atom Charge Exchange Cross Sections: The Role Of Electron Saddle Swaps

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.Fil: Otranto, Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - CONICET - Bahía Blanca. Instituto de Física del Sur; Argentina. Universidad Nacional del Sur. Departamento de Física; ArgentinaFil: Blank, I.. Kernfysisch Versneller Instituut. Atomic Physics; Países BajosFil: Olson, R. E.. Missouri University of Science and Technology; Estados UnidosFil: Hoekstra, R.. Kernfysisch Versneller Instituut. Atomic Physics; Países Bajo

The Role of Multiple Electron Processes for Fast Ion H₂O Collisions

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