Probing Positron Cooling in Noble Gases via Annihilation 
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 Spectra

Green, D. G.

doi:10.1103/physrevlett.119.203404

Cited by 9 publications

(4 citation statements)

References 39 publications

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“…New experiments of positron cooling in neon are now warranted. Such experiments may include complementary measurements of the time-varying γ spectra during cooling, which have been shown to be sensitive to the positron cooling times [41].…”

Section: Discussionmentioning

confidence: 99%

Positron Cooling and Annihilation in Noble Gases

Green

2017

Phys. Rev. Lett.

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Section: Discussionmentioning

confidence: 99%

Positron Cooling and Annihilation in Noble Gases

Green

2017

Phys. Rev. Lett.

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“…A powerful method that accurately describes positron-electron correlations in a systematic, intuitive, and computationally scalable way is the many-body theory [16][17][18][19][20][21][22][23][24][25][26]. It has provided a full ab initio description of positron scattering and annihilation rates in atoms [16,18], annihilation γ spectra [27], and positron cooling in noble gas atoms [28,29], solving a number of longstanding problems. Moreover, the approach enabled ab initio calculations of annihilation vertex enhancement factors that can be used to calculate core annihilation probabilities in condensed matter [24] and also enabled a many-body approach to calculations of Ps-atom scattering and pickoff annihilation [30,31].…”

Section: Introductionmentioning

confidence: 99%

Many-body theory calculations of positron scattering and annihilation in noble-gas atoms via the solution of Bethe–Salpeter equations using the Gaussian-basis code EXCITON+

Hofierka,

Rawlins,

Cunningham

et al. 2023

Front. Phys.

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Scattering phase shifts and annihilation rates for low-energy positrons interacting with noble gas atoms are calculated ab initio using many-body theory implemented in the Gaussian-orbital code EXCITON+. Specifically, we construct the positron–atom correlation potential (self-energy) as the sum of three classes of infinite series describing the screened polarization, virtual positronium formation, and positron-hole repulsion found via the solution of Bethe–Salpeter equations for the two-particle propagators. The normalization of the continuum states is determined using the shifted pseudostates method [A. R. Swann and G. F. Gribakin, Phys. Rev. A 101, 022702 (2020)]. Comparison with the previous sophisticated B-spline many-body approach, which is restricted to atoms [J. Ludlow, D. G. Green, and G. F. Gribakin, Phys. Rev. A 90, 032712 (2014)], validates the EXCITON+ code, which can be used for multicentered targets including molecules, clusters, and condensed matter. Moreover, the relative effects of higher-order diagrams are quantified. It is found that the screening of the electron–positron Coulomb interaction represented by the infinite ring-diagram series (random-phase approximation) is compensated effectively by the additional electron-hole attraction corrections to it (the Bethe–Salpeter equation approximation) and that the use of the screened Coulomb interaction (screened at BSE level) in place of the bare Coulomb interaction in the virtual positronium and positron-hole ladder diagrams has negligible effect on both the phase shifts and Zeff. Our scattering length for Ne and Kr is in improved agreement with the convergent close-coupling result, and for Ar, the scattering length is in better agreement with the experiment compared with the previous B-spline many-body approach.

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“…Many-body theory (MBT) is a powerful and systematic method of accounting for virtual excitations of both objects and the electron-positron correlation effects. It provided an accurate description of low-energy electron-atom scattering [23][24][25][26][27][28] and positron interaction with atoms [19,20,[29][30][31][32][33], with scattering cross sections, annihilation rates, and γ spectra all found to be in excellent agreement with experiment.…”

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confidence: 91%

Many-Body Theory for Positronium-Atom Interactions

2018

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A many-body-theory approach has been developed to study positronium-atom interactions. As first applications, we calculate the elastic scattering and momentum-transfer cross sections and the pickoff annihilation rate ^{1}Z_{eff} for Ps collisions with He and Ne. For He the cross section is in agreement with previous coupled-state calculations, while comparison with experiment for both atoms highlights discrepancies between various sets of measured data. In contrast, the calculated ^{1}Z_{eff} (0.13 and 0.26 for He and Ne, respectively) are in excellent agreement with the measured values.

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Probing Positron Cooling in Noble Gases via Annihilation γ Spectra

Cited by 9 publications

References 39 publications

Positron Cooling and Annihilation in Noble Gases

Positron Cooling and Annihilation in Noble Gases

Many-body theory calculations of positron scattering and annihilation in noble-gas atoms via the solution of Bethe–Salpeter equations using the Gaussian-basis code EXCITON+

Many-Body Theory for Positronium-Atom Interactions

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