<i>T</i>-matrix theory of positron annihilation on hydrogen

Ryzhikh, G. G.; Mitroy, Jim

doi:10.1088/0953-4075/33/12/306

Cited by 41 publications

(40 citation statements)

References 46 publications

(73 reference statements)

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“…The present Z eff agrees well with those by Van Reeth and Humberston [4] and by Ryzhikh and Mitroy [5] within 5%. The work of Laricchia and Wilkin [3] has been critically assessed earlier [5,7], and no further comment is due here. The result obtained by Yamanaka and Kino [6], using a timedependent version of Eq.…”

supporting

confidence: 92%

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Unified Treatment of Positron Annihilation and Positronium Formation

2002

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The effects of the positron (e(+)) annihilation in e(+) scattering by the H atom are included directly in the Hamiltonian as an absorption potential, and hence the finite lifetimes Gamma(ns) of positronium (Ps) in states ns are automatically taken account of. The Schrödinger equation is solved using the hyperspherical close-coupling method. The annihilation and Ps formation are shown to be inseparable near the Ps(1s) threshold E(th); Ps formation constitutes just an indirect pathway to annihilation. The annihilation cross section, which would diverge near E(th) if Gamma(1s) were infinite, connects smoothly across E(th) to the cross section for Ps formation, which is meaningful only at energies well above E(th).

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supporting

confidence: 92%

“…detailed variational calculations for the e H collisions, though their results are grossly different from the Laricchia-Wilkin model. Ryzhikh and Mitroy [5] found that Eq. (1) they calculated using the momentum-space Lippmann-Schwinger equation lies within a few % difference from the result of Ref.…”

mentioning

confidence: 99%

Unified Treatment of Positron Annihilation and Positronium Formation

2002

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“…Besides reproducing the low-energy elastic cross section, this model potential approach also does a reasonable job of reproducing Z eff (v). The annihilation parameter is computed from the scattering wave function using [4,25,26] …”

Section: Collision Modelmentioning

confidence: 99%

Transport theory for low-energy positron thermalization and annihilation in helium

et al. 2014

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A transport theory that explicitly incorporates loss of flux due to annihilating collisions is developed and applied to low-energy positron diffusion and annihilation. The use of more complete momentum transfer and annihilation cross sections for helium has resulted in improved descriptions of the time dependence of Z eff for positrons injected into gaseous helium. Similarly, the variation of Z eff versus E/n 0 for experiments where the annihilation region is immersed in an electric field is in closer agreement with experimental data. Inclusion of loss of flux due to annihilation was found to have a very small effect on the derived Z eff (t) for helium.

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“…The annihilation parameter Z eff is computed from the scattering wave function using the identity [23][24][25],…”

Section: G Positron Annihilationmentioning

confidence: 99%

Stochastic variational calculation of zero-energy positron scattering from H, He, andH2

Zhang

Mitroy

2011

Phys. Rev. A

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The confined variational method is used to generate a set of energy-optimized explicitly correlated Gaussians to describe positrons interacting with H, He and the H 2 molecule. These basis functions are then used in a Kohn variational calculation of the scattering lengths and zero-energy annihilation parameters, Z eff . The results for the H and He atoms are consistent with previous high-quality variational calculations while the annihilation parameter for H 2 is consistent with experiment. An extensive tabulation of the H 2 scattering parameters as a function of internuclear distance confirm the existence of a virtual state at R ≈ 3.4a 0 . The scattering length was −2.71a 0 and Z eff was 15.7 at the mean H 2 internuclear distance of 1.45a 0 .

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T-matrix theory of positron annihilation on hydrogen

Cited by 41 publications

References 46 publications

Unified Treatment of Positron Annihilation and Positronium Formation

Unified Treatment of Positron Annihilation and Positronium Formation

Transport theory for low-energy positron thermalization and annihilation in helium

Stochastic variational calculation of zero-energy positron scattering from H, He, andH2

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