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Berg, H. P.; Jagutzki, O.; Dørner, R.; DuBois, R.D.; Kelbch, C.; Schmidt‐Böcking, H.; Ullrich, J.; Ja, Tanis; As, Schlachter; Blumenfeld, Lev; d'Etat, Brigitte Ban; Hagmann, S.; Gonzales, Ashley E.; Quinteros, T.

doi:10.1103/physreva.46.5539

Cited by 30 publications

(26 citation statements)

References 34 publications

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“…In subsequent publications of different authors, it was estimated that the high-iv> limit of R for N 7+ projectiles should be reached only for velocities close to the velocity of light. It was argued that the observed large experimental value for the ratio can be attributed to the contribution of the "twostep" mechanism to the double ionization cross section [12,13] or to an interference term between "shake-off" and "two-step" processes [14]. These arguments were supported by a more recent experimental data point for N 7 " 1 " projectiles at 40 MeV/u, reported by the same authors [15], which lies significantly below the former results and thus suggests a decreasing tendency of R towards higher energies.…”

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confidence: 96%

High-velocity limit for the ratio of helium double-to-single ionization for highly charged, bare-ion impact

et al. 1993

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The ratio R of helium double-to-single ionization cross sections was measured for Ne ,0+ and Ni 28+ projectiles at velocities of 0.39 < vp/c < 0.93 intending to explore the high-velocity limit of R for highly charged ion impact. For Ne ,0+ projectiles R was observed to become independent of vp for vp/ciZ0J3 and an asymptotic experimental value R = (2.57 ±0.10)x 10 -3 has been established. This is in good agreement with experimental results for proton, antiproton, electron, and positron impact and in excellent accordance with the theoretical prediction of (2.59 ±0.03) x 10 ~3.PACS numbers: 34.50.FaThe most simple and therefore fundamental dynamical many-electron problem in atomic collision physics is the simultaneous transfer of two helium electrons into excited or continuum states by energetic charged particle or photon impact. The central potential of the helium nucleus is comparably weak and the correlated motion of the two electrons before, during, and after the collision plays an essential role in such a situation. Thus, static and dynamic correlation between the electrons both have considerable influence on the magnitude of even total cross sections for helium double ionization (), one finds experimentally [1,2] a constant value at large r/>, which is independent of the velocity.In this so-called high-velocity limit, the perturbation by the projectile is so small that the probability for its simultaneous and independent interaction with both target electrons (so-called "two-step" mechanism), which is the reason for double ionization in an independent electron model, can be completely neglected. Double ionization is induced by only one single interaction of the projectile with one target electron (single ionization). It solely occurs due to the electron-electron interaction and the ratio 7?=cr 2+ /<7 1+ therefore is extremely sensitive to the details of the time-dependent electronic motion. This is underlined by the fact that R is about a factor of 5 larger for energetic photon [3] than for charged particle impact. As a further consequence, the high-velocity limit of R is predicted to be independent of the sign of the projectile charge q and velocity vp. Systematic experiments with singly charged projectiles for electron [4,5], proton [6], antiproton [7,8], and positron [9] impact indeed yielded identical ratios within the experimental errors between 0.24% and 0.28%. This value is in good agreement with theoretical results of ab initio calculations by Ford and Reading [10] for charged particle impact of R =0.259%.For highly charged ion impact it is expected that R should settle at the same asymptotic value. Since in first order the perturbation is proportional to ...

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confidence: 96%

High-velocity limit for the ratio of helium double-to-single ionization for highly charged, bare-ion impact

et al. 1993

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“…4 -The sudden approximation [17]. Fig.2 Experimental results from [20] and results of calculations (by formulae ( 25) and ( 23) • -experiment, × -calculations. ✷ -experiment from [28], △ -our results.…”

Section: Resultsmentioning

confidence: 99%

“…In Fig.2 the results of experiments from [20], the results of calculations obtained using formulae ( 25) and ( 23) [23,24,25]). …”

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Inelastic collisions of relativistic highly charged ions with atoms

Matveev

Rakhimov

Matrasulov

1999

J. Phys. B: At. Mol. Opt. Phys.

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A general expression for the cross sections of inelastic collisions of fast (including relativistic) multicharged ions with atoms which is based on the genelazition of the eikonal approximation is derived. This expression is applicable for wide range of collision energy and has the standard nonrelativistic limit and in the ultrarelativistic limit coincides with the Baltz's exact solution [1] of the Dirac equation.As an application of the obtained result the following processes are calculated: the excitation and ionization cross sections of hydrogenlike atom; the single and double excitation and ionization of heliumlike atom; the multiply ionization of neon and argon atoms; the probability and cross section of K-vacancy production in the relativistic U 92+ − U 91+ collision. The simple analytic formulae for the cross sections of inelastic collisions and the recurrence relations between the ionization cross sections of different multiplicities are also obtained. Comparison of our results with the experimental data and the results of other calculations are given.

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“…Our analysis is based on a large database of published experimental cross sections and double-ionization ratios [7][8][9][10][11][12][13][26][27][28][29][30][31][32][33][34][35][36][37][38]. To simplify the interpretation, only data for the direct ionization channel, i.e., only data where there are no contributions from the electron-capture channel, and fully stripped projectile impact were used.…”

Section: Analysis Proceduresmentioning

confidence: 99%

“…To extend our analysis to multiply charged ion impact, experimental cross sections for He 2+ [9,[26][27][28]38], Li 3+ [26,29], F 9+ [31], and U 90+ [34] impact were used. Guided by the scaling found in Fig.…”

Section: Ionization By Bare Multiply Charged Ionsmentioning

confidence: 99%

Empirical formulas for direct double ionization by bare ions:Z=−1to 92

2014

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Experimental cross sections and cross-section ratios reported in the literature for direct double ionization of the outer shells of helium, neon, and argon atoms resulting from bare ions ranging from protons to uranium and for antiprotons are analyzed in terms of a first-and second-order interference model originally proposed by McGuire [J. H. McGuire, Phys. Rev. Lett. 49, 1153(1982]. Empirical formulas for the various contributions to double ionization plus information about the phase difference between the first-and second-order mechanisms are extracted from the data. Projectile and target scalings are also extracted. Total cross sections and their ratios determined using these formulas and scalings are shown to be in very good agreement with experimental data for lower-Z projectiles and impact velocities larger than 1 a.u. For very-high-Z projectiles, the amount of double ionization is overestimated, probably due to saturation of probabilities that is not accounted for in scaling formulas.

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Double ionization of helium by high-velocityU90+ions

Cited by 30 publications

References 34 publications

High-velocity limit for the ratio of helium double-to-single ionization for highly charged, bare-ion impact

High-velocity limit for the ratio of helium double-to-single ionization for highly charged, bare-ion impact

Inelastic collisions of relativistic highly charged ions with atoms

Empirical formulas for direct double ionization by bare ions:Z=−1to 92

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