On the double ionization of helium by very slow antiproton impact

Knudsen, H.; Kristiansen, Helle; Thomsen, Heine; Uggerhøj, U. I.; Ichioka, T.; Møller, S.P.; Hunniford, Christopher; McCullough, R W; Charlton, M.; Kuroda, N.; Nagata, Y.; Torii, H. A.; Yamazaki, Y.; Imao, H.; Andersen, H. H.; Tőkési, K.

doi:10.1016/j.nimb.2008.10.070

Cited by 20 publications

(21 citation statements)

References 19 publications

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“…The present results show a better overall agreement with the experimental data [1][2][3][4] than other ab initio calculations [6-9, 11-14, 16]. We have also presented the first doubly differential cross sections for single ionization at 10 and 100 keV antiproton energies which were obtained by considering the fully correlated two-electron dynamics of the He + p collisional system.…”

Section: Discussionsupporting

confidence: 81%

“…2), the present TDCC double ionization total cross sections are in excellent agreement with the experimental data over the entire range of antiproton energies considered. The experimental data consist of three sets of Andersen et al [1] (CERN90), of Hvelplund et al [2] (CERN94), and Knudsen et al [4] (CERN09). Also, the different TDCC calculations are in close agreement with each other.…”

Section: Total Ionization Cross Sectionmentioning

confidence: 99%

“…The collision of antiprotons with helium atoms is a fundamental process in many-body atomic physics attracting considerable interest from both the experimental [1][2][3][4][5] and theoretical [5][6][7][8][9] side. This collision system is an ideal candidate to study the four-body Coulomb problem because the number of possible reaction channels is limited: the negative charge of the projectile blocks the electron capture channel and because of the large mass of the projectile, rearrangement processes involving capture of the antiproton by the helium atom are strongly suppressed except at very low energies (∼ eV).…”

Section: Introductionmentioning

confidence: 99%

“…Up to now, only total cross sections for single and double ionization have been measured for impact energies ranging from 3 keV up to a few MeV [1][2][3][4]. At high impact energies (above 100 keV) the single ionization (SI) process is predominantly a one-electron process, and can be fairly accurately described using single active electron (SAE) approaches [10][11][12].…”

Section: Introductionmentioning

confidence: 99%

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Ionization of helium by slow antiproton impact: Total and differential cross sections

et al. 2014

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We theoretically investigate the single and double ionization of the He atom by antiproton impact for projectile energies ranging from 3 keV up to 1000 keV. We obtain accurate total cross sections by directly solving the fully correlated two-electron time-dependent Schrödinger equation and by performing classical trajectory Monte-Carlo calculations. The obtained quantum-mechanical results are in excellent agreement with the available experimental data. Along with the total cross sections, we also present the first fully ab initio doubly differential data for single ionization at 10 and 100 keV impact energies. In these differential cross sections we identify the binary-encounter peak along with the anticusp minimum. Furthermore, we also point out the importance of the postcollisional electron-projectile interaction at low antiproton energies which significantly suppresses electron emission in the forward direction.

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Section: Discussionsupporting

confidence: 81%

Section: Total Ionization Cross Sectionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Ionization of helium by slow antiproton impact: Total and differential cross sections

et al. 2014

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“…In agreement with the findings of Knudsen et al, they found that for larger Z/v the ratios increased as v −2 but were velocity independent as Z/v → 0. Antiproton and proton impact data were compared [10][11][12][13] with the observed differences in the double ionization being attributed to quantum interference, in accordance with the McGuire model. For a synopsis of the antiproton and proton studies see [11] and references therein.…”

Section: Introductionmentioning

confidence: 85%

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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Realization of nanosecond antiproton pulses in the ultra-low energy storage ring

Papash

Welsch

2010

Nuclear Instruments and Methods in Physics Research Section A:

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On the double ionization of helium by very slow antiproton impact

Cited by 20 publications

References 19 publications

Ionization of helium by slow antiproton impact: Total and differential cross sections

Ionization of helium by slow antiproton impact: Total and differential cross sections

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

Realization of nanosecond antiproton pulses in the ultra-low energy storage ring

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