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Title: Multiple electron emission from noble gases colliding with proton beams, including postcollisional effects

Abstract

The process of multiple electron ionization of Ne and Ar noble gases produced by impact of proton beams is studied in the framework of the independent-electron model. The role played by different mechanisms is analyzed, including intershell Auger and intrashell Coster-Kronig electron emission, which follow the production of vacancies due to direct interaction of the projectile with the target electrons. The present results, obtained with the continuum distorted wave-eikonal initial state (CDW-EIS) approximation, confirm previous predictions given by a different theoretical model. Semiempirical approximations are introduced by using analytical single-ionization probabilities with adjustable parameters determined from CDW-EIS total cross sections. The small computational time required to calculate multiple ionization cross sections with these semiempirical approximations and the good agreement found with existing experimental data and with results obtained with more elaborated theoretical models make them good candidates to study electron emission from complex targets.

Authors:
; ;  [1];  [2]
  1. Instituto de Fisica Rosario (CONICET-UNR) and Escuela de Ciencias Exactas y Naturales, Universidad Nacional de Rosario, Avenida Pellegrini 250, 2000 Rosario (Argentina)
  2. (Argentina)
Publication Date:
OSTI Identifier:
20982526
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. A; Journal Volume: 75; Journal Issue: 5; Other Information: DOI: 10.1103/PhysRevA.75.052708; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; ARGON; AUGER EFFECT; CATIONS; COSTER-KRONIG TRANSITIONS; DISTORTED WAVE THEORY; EIKONAL APPROXIMATION; ELECTRON EMISSION; ENERGY-LEVEL TRANSITIONS; FORECASTING; HYDROGEN IONS; INTERACTIONS; ION-ATOM COLLISIONS; IONIZATION; NEON; PROBABILITY; PROTON BEAMS; RARE GASES; TOTAL CROSS SECTIONS; VACANCIES

Citation Formats

Galassi, M. E., Rivarola, R. D., Fainstein, P. D., and Centro Atomico Bariloche, Comision Nacional de Energia Atomica, 8400 Bariloche, Rio Negro. Multiple electron emission from noble gases colliding with proton beams, including postcollisional effects. United States: N. p., 2007. Web. doi:10.1103/PHYSREVA.75.052708.
Galassi, M. E., Rivarola, R. D., Fainstein, P. D., & Centro Atomico Bariloche, Comision Nacional de Energia Atomica, 8400 Bariloche, Rio Negro. Multiple electron emission from noble gases colliding with proton beams, including postcollisional effects. United States. doi:10.1103/PHYSREVA.75.052708.
Galassi, M. E., Rivarola, R. D., Fainstein, P. D., and Centro Atomico Bariloche, Comision Nacional de Energia Atomica, 8400 Bariloche, Rio Negro. Tue . "Multiple electron emission from noble gases colliding with proton beams, including postcollisional effects". United States. doi:10.1103/PHYSREVA.75.052708.
@article{osti_20982526,
title = {Multiple electron emission from noble gases colliding with proton beams, including postcollisional effects},
author = {Galassi, M. E. and Rivarola, R. D. and Fainstein, P. D. and Centro Atomico Bariloche, Comision Nacional de Energia Atomica, 8400 Bariloche, Rio Negro},
abstractNote = {The process of multiple electron ionization of Ne and Ar noble gases produced by impact of proton beams is studied in the framework of the independent-electron model. The role played by different mechanisms is analyzed, including intershell Auger and intrashell Coster-Kronig electron emission, which follow the production of vacancies due to direct interaction of the projectile with the target electrons. The present results, obtained with the continuum distorted wave-eikonal initial state (CDW-EIS) approximation, confirm previous predictions given by a different theoretical model. Semiempirical approximations are introduced by using analytical single-ionization probabilities with adjustable parameters determined from CDW-EIS total cross sections. The small computational time required to calculate multiple ionization cross sections with these semiempirical approximations and the good agreement found with existing experimental data and with results obtained with more elaborated theoretical models make them good candidates to study electron emission from complex targets.},
doi = {10.1103/PHYSREVA.75.052708},
journal = {Physical Review. A},
number = 5,
volume = 75,
place = {United States},
year = {Tue May 15 00:00:00 EDT 2007},
month = {Tue May 15 00:00:00 EDT 2007}
}
  • Cross sections for the elastic scattering of electrons from neon, argon and krypton will be presented for energies in the range from threshold to 40 eV. These calculations include the effects of dynamic distortion within the polarized-orbital approximation. The effects arise from the kinetic energy term of the Hamiltonian operating on the first-order polarized orbital and result in a modification of the coefficients in the asymptotic expansion of the scattering potential starting with the quadrupole term. Improved results are obtained for argon and krypton but not for neon. We attribute this behaviour to accurate values for these asymptotic coefficients formore » argon and krypton and less accurate values in the case of neon.« less
  • Cross sections for electron emission in the energy range from 2--300 eV were measured for 60 MeV/u Kr{sup 34+} ions impacting on H{sub 2} . Model calculations are introduced to guide the search for interference effects in the electron spectra produced by the coherent emission of electrons from the two H atoms in analogy with Young's two-slit experiment. Experimentally, a full sinusoidal-like oscillation was observed in the energy range up to 250 eV in good agreement with the calculations. The oscillatory structure is found to be similar for the observation angles 20{sup o} , 30{sup o} , 150{sup o} ,more » and 160{sup o} .« less
  • Absolute charge-state-correlated cross sections for projectile electron loss, electron capture, and target multiple ionization in collisions between C{sup 3+} ions and noble gases have been measured for energies between 1.3 and 3.5 MeV. The data have been compared with other similar absolute cross sections existent in the literature for several projectiles. Calculations for the single-loss-multiple-ionization channel have been performed for the screening mode, using both an extended version of the classical-impulse free-collision model and the plane-wave Born approximation (PWBA), and for the antiscreening mode within the PWBA. The energy dependence of the average number of target active electrons which contributemore » to the antiscreening has been described by means of a simple function, which is ''universal'' for noble gases but, in principle, projectile dependent. A method has been developed to obtain the number of active target electrons for each subshell in the high-velocity regime, which presented physically reasonable results. Analyses of the dependences of the single-capture and transfer-ionization (SC and TI, respectively) processes on the projectile charge states showed that, for He, equally charged bare and dressed projectiles have very similar cross sections; the latter thus acting as structureless point charges. A behavior similar to that in the SC has been observed for the pure single ionization of He by projectiles with different charge states and of the other noble gases by singly charged projectiles. It has been shown that the q{sup 2} dependence of the pure-single and total-ionization cross sections, predicted by first-order models, is only valid for high-collision velocities. For slower collisions, the electron capture process becomes more relevant and competes with the ionization channel, a feature which grows in importance as the projectile charge state increases.« less