Positron-hydrogen-like-ion scattering

Khan, Pritikana; Mazumder, P. S.; Ghosh, Arnab

doi:10.1007/bf02117210

Cited by 7 publications

(18 citation statements)

References 8 publications

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“…The P-and D-wave phase shifts of the present calculation agree excellently with those calculated by Bransden et al (2001) at most of the energies displayed, except for a few values at higher energies where the agreement is not excellent but still very good. They, of course, disagree considerably with those calculated by Khan et al (1984). The S-wave results of our present calculation also disagree considerably with those of Khan et al and those of Shimamura (1971).…”

contrasting

confidence: 67%

“…In table 1, we show the results of the present calculation, using the E8S scheme described above, for the S-, P-and D-partial waves, together with the values obtained by other researchers and available in the literature (Bransden et al 2001, Khan et al 1984, Shimamura 1971 for comparison. The phase shifts shown in this table are at the energies where other groups also did their calculation.…”

mentioning

confidence: 93%

“…For positron scattering from He + at energies below its first excitation threshold energy (∼40.8 eV), there has been a calculation by Shimamura (1971) employing the Harris method (1967) but for S wave scattering only. There has also been a calculation by Khan et al (1984) employing the polarized-orbital method for S-, P-and D-wave scattering and very recently, a calculation by Bransden et al (2001) employing the coupled-channel approximation method. Unfortunately, the results of phase shift obtained by these various research groups disagree considerably with each other.…”

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confidence: 99%

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Accurate calculation of phase shifts for positron-He⁺collisions

Gien

2001

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

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We considered the Harris-Nesbet variational method for an accurate calculation of phase shifts in positron-He+ collisions. Calculations have been carried out for L = 0, 1, 2, 3, 4, 5, 6 partial waves. Very accurate results of phase shift have been obtained for the first time. The accuracy has been double-checked by carrying out the calculations with the use of different large-coupling schemes. We compare our results with those available in the literature.

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confidence: 67%

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confidence: 93%

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confidence: 99%

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Accurate calculation of phase shifts for positron-He⁺collisions

Gien

2001

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

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“…The limited attention that has been paid to both the scattering problem and resonance search generated some controversy. Phase shifts for positron scattering on He + , Li 2+ , Be 3+ , and B 4+ were calculated by Shimamura [16], using the Harris method for s-wave scattering only, and by Khan et al [17], using the polarized orbital approximation for s, p, and d waves. Abdel-Raouf [18] used a two-state coupled-channel approximation to study the cross sections of the collisions of positrons with various hydrogenlike targets, both above and below the positronium-formation threshold.…”

Section: Introductionmentioning

confidence: 99%

Positron scattering and annihilation in hydrogenlike ions

Green

Gribakin

2013

Phys. Rev. A

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Diagrammatic many-body theory is used to calculate the scattering phase shifts, normalized annihilation rates Z eff , and annihilation γ spectra for positron collisions with the hydrogenlike ions He + , Li 2+ , B 4+ , and F 8+. Short-range electron-positron correlations and longer-range positron-ion correlations are accounted for by evaluating nonlocal corrections to the annihilation vertex and the exact positron self-energy. The numerical calculation of the many-body theory diagrams is performed using B-spline basis sets. To elucidate the role of the positron-ion repulsion, the annihilation rate is also estimated analytically in the Coulomb-Born approximation. It is found that the energy dependence and magnitude of Z eff are governed by the Gamow factor that characterizes the suppression of the positron wave function near the ion. For all of the H-like ions, the correlation enhancement of the annihilation rate is found to be predominantly due to corrections to the annihilation vertex, while the corrections to the positron wave function play only a minor role. Results of the calculations for s-, p-, and d-wave incident positrons of energies up to the positronium-formation threshold are presented. Where comparison is possible, our values are in excellent agreement with the results obtained using other, e.g., variational, methods. The annihilation-vertex enhancement factors obtained in the present calculations are found to scale approximately as 1 + (1.6 + 0.46)/Z i , where Z i is the net charge of the ion and is the positron orbital angular momentum. Our results for positron annihilation in H-like ions provide insights into the problem of positron annihilation with core electrons in atoms and condensed matter systems, which have similar binding energies.

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“…The limited attention that has been paid to both the scattering problem and resonance search generated some controversy. Phase shifts for positron scattering on He + , Li 2+ , Be 3+ and B 4+ were calculated by Shimamura [14], using the Harris method for s-wave scattering only, and by Khan [15], using the polarized orbital approximation for s, p and d waves. Abdel-Raouf [16] used a two-state coupled channel approximation to study the cross sections of the collisions of positrons with various hydrogenlike targets, both above and below the positronium formation threshold.…”

Section: Introductionmentioning

confidence: 99%

Positron annihilation in hydrogen-like ions

Green

Gribakin

2012

J. Phys.: Conf. Ser.

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Diagrammatic many-body theory is used to calculate the scattering phase shifts, normalized annihilation rates Z eff and annihilation γ-spectra for positron collisions with the hydrogen-like ions He + , Li 2+ , B 4+ and F 8+ . Short-range electron-positron correlations and longer-range positron-ion correlations are accounted for by evaluating nonlocal corrections to the annihilation vertex and the exact positron self-energy. The numerical calculation of the many-body theory diagrams is performed using B-spline basis sets. To elucidate the rôle of the positron-ion repulsion, the annihilation rate is also estimated analytically in the Coulomb-Born approximation. It is found that the energy dependence and magnitude of Z eff is governed by the Gamow factor that characterizes the suppression of the positron wave function near the ion. For all of the H-like ions, the correlation enhancement of the annihilation rate is found to be predominantly due to corrections to the annihilation vertex, while the corrections to the positron wave function play only a minor rôle. Results of the calculations for s, p and d-wave incident positrons of energies up to the positronium formation threshold are presented. Where comparison is possible, our values are in excellent agreement with the results obtained using other, e.g., variational, methods. The annihilation vertex enhancement factors obtained in the present calculations are found to scale approximately as 1 + (1.6 + 0.46 )/Zi, where Zi is the net charge of the ion and is the positron orbital angular momentum. Our results for positron annihilation in H-like ions provide insights into the problem of positron annihilation with core electrons in atoms and condensed matter systems, which have similar binding energies.

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Positron-hydrogen-like-ion scattering

Cited by 7 publications

References 8 publications

Accurate calculation of phase shifts for positron-He⁺collisions

Accurate calculation of phase shifts for positron-He⁺collisions

Positron scattering and annihilation in hydrogenlike ions

Positron annihilation in hydrogen-like ions

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Positron-hydrogen-like-ion scattering

Cited by 7 publications

References 8 publications

Accurate calculation of phase shifts for positron-He+collisions

Accurate calculation of phase shifts for positron-He+collisions

Positron scattering and annihilation in hydrogenlike ions

Positron annihilation in hydrogen-like ions

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Accurate calculation of phase shifts for positron-He⁺collisions

Accurate calculation of phase shifts for positron-He⁺collisions