Multi-ionization of helium by slow highly charged ions

Shao, Jianxiong; Chen, X. M.; Liu, Z. Y.; Rongfei, Qi; Zou, X. R.

doi:10.1103/physreva.77.042711

Cited by 19 publications

(15 citation statements)

References 26 publications

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“…The cross sections for the first three processes are essentially proportional to the single-ionization cross section, while those for the latter-which is the dominant process in the low-to intermediate-velocity region [13]-depend on the projectile velocity and charge state quite differently than the singleionization ones. However, even in this case, the dependences of the cross sections on the projectile charge states and/or the influence of competitive collision channels can be quite strong, as has been shown for the ratio between double and single ionization of the He target with and without the simultaneous electron loss or capture by dressed C and/or O projectile ions, in the low-to intermediate-velocity regime [14][15][16][17][18].…”

Section: Introductionmentioning

confidence: 93%

“…16. Pure single-ionization cross sections of He by triply charged projectiles as a function of the projectile velocity in atomic units.…”

Section: Pure Multiple Ionizationmentioning

confidence: 99%

“…[14][15][16][17][18][47][48][49][50][51][52][53][54][55]). Absolute measurements of multiple-ionization cross sections are rather scarce; moreover when one looks for exclusive measurements, where the final charge states not only of the target but also of the projectile are obtained in coincidence.…”

Section: Introductionmentioning

confidence: 99%

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Absolute cross sections for electron loss, electron capture, and multiple ionization in collisions ofC3+with noble gases

et al. 2010

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Absolute charge-state-correlated cross sections for projectile electron loss, electron capture, and target multiple ionization in collisions between C 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 contribute 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 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.

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Section: Introductionmentioning

confidence: 93%

“…16. Pure single-ionization cross sections of He by triply charged projectiles as a function of the projectile velocity in atomic units.…”

Section: Pure Multiple Ionizationmentioning

confidence: 99%

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Absolute cross sections for electron loss, electron capture, and multiple ionization in collisions ofC3+with noble gases

et al. 2010

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“…We recently noted this [24,25] and attempted to interpret the proton and antiproton data solely in terms of the first-order SO and TS1 mechanisms, which were assumed to interfere. We note that Shao et al also found a v −1 behavior for conditions where Z/v >1 [22,23]. To investigate the different velocity dependences for the Z = 1 and higher-Z projectiles, plus to fully test the first-and second-order interference model of McGuire, the experimental asymptotic high-energy ratio, which is assumed to be entirely first order, R 1st (Ý) = 0.002 59 [7], was subtracted from each experimental R 2 value in Fig.…”

Section: Analysis Proceduresmentioning

confidence: 85%

“…They attributed the remaining discrepancies to the lack of correlation in their model. A different model based up the strong electric field of the projectile leading to ejection or capture of target electrons has also been proposed [22,23], but its range of application should be limited to regions where Z/v is large and, in contrast to the McGuire and several other models, has no explicit first-order and second-order interference contributions to explain the observed differences in double ionization resulting from positive-and negativeprojectile impact.…”

Section: Introductionmentioning

confidence: 98%

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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Classical calculation of multiple-ionization cross-sections of noble gases near Bragg peak energies

et al. 2013

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In this paper, we extend our previous work of classical over barrier ionization (COBI) model to study the multiple-ionization and mean charge state of noble gases colliding with heavy ions at energies close to the Bragg peak region ranging up to some hundreds of keV/amu. The method we report is in good agreement with experimental data and offers the advantage of very small computation time. Therefore, this model will be extremely helpful to be included in numerical codes to calculate the charge state distribution in plasma.

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Multi-ionization of helium by slow highly charged ions

Cited by 19 publications

References 26 publications

Absolute cross sections for electron loss, electron capture, and multiple ionization in collisions ofC3+with noble gases

Absolute cross sections for electron loss, electron capture, and multiple ionization in collisions ofC3+with noble gases

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

Classical calculation of multiple-ionization cross-sections of noble gases near Bragg peak energies

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