Positronium formation in collisions between positrons and alkali-metal atoms (Li, Na, K, Rb and Cs) in Debye plasma environments

Pandey, Mukesh Kumar; Lin, Yi-Ting; Ho, Y. K.

doi:10.1088/0953-4075/49/3/034007

Cited by 21 publications

(11 citation statements)

References 122 publications

(74 reference statements)

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“…al. [112] have studied the Ps formation in positron-alkali-metal collisions in Debye plasmas based on the Debye screening of an electron-ion core model potential.…”

Section: Positron Collisionsmentioning

confidence: 99%

Review of quantum collision dynamics in Debye plasmas

Janev

Zhang

Wang

2016

Matter and Radiation at Extremes

144

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Hot, dense plasmas exhibit screened Coulomb interactions, resulting from the collective effects of correlated many-particle interactions. In the lowest particle correlation order (pair-wise correlations), the interaction between charged plasma particles reduces to the Debye-Hückel (Yukawa-type) potential, characterized by the Debye screening length D. Due to the importance of Coulomb interaction screening in dense laboratory and astrophysical plasmas, hundreds of theoretical investigations have been carried out in the past few decades on the plasma screening effects on the electronic structure of atoms and their collision processes employing the Debye-Hückel screening model. The present article aims at providing a comprehensive review of the recent studies in atomic physics in Debye plasmas. Specifically, the work on atomic electronic structure, photon excitation and ionization, electron/positron impact excitation and ionization, and excitation, ionization and charge transfer of ion-atom/ion collisions will be reviewed.

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“…al. [112] have studied the Ps formation in positron-alkali-metal collisions in Debye plasmas based on the Debye screening of an electron-ion core model potential.…”

Section: Positron Collisionsmentioning

confidence: 99%

Review of quantum collision dynamics in Debye plasmas

Janev

Zhang

Wang

2016

Matter and Radiation at Extremes

144

View full text Add to dashboard Cite

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“…Possible production of Bose-Einstein condensate of Ps has also been predicted [7,8], besides the importance of Ps in diagnosing porous materials [9] as well as in probing bound-state QED effects [10]. Moreover, efficient Ps formation is the precursor of the production of dipositronium molecules [11] and antihydrogen atoms [12,13] required to study the effect of gravitational force on antimatter [14,15].Theoretical investigations to calculate Ps formation cross sections from atomic hydrogen [16][17][18], noble gases [19][20][21], and alkali metals [22,23] are aplenty. Calculations with molecular targets, although relatively limited, include the molecular hydrogen [24], polyatomic molecules [25], and the water molecule [26].…”

mentioning

confidence: 99%

“…Theoretical investigations to calculate Ps formation cross sections from atomic hydrogen [16][17][18], noble gases [19][20][21], and alkali metals [22,23] are aplenty. Calculations with molecular targets, although relatively limited, include the molecular hydrogen [24], polyatomic molecules [25], and the water molecule [26].…”

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confidence: 99%

Ubiquitous diffraction resonances in positronium formation from fullerenes

Hervieux

Chakraborty

2017

Phys. Rev. A

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Due to the dominant electron capture by positrons from the molecular wall and the spatial dephasing across the wall-width, a powerful diffraction effect universally underlies the positronium (Ps) formation from fullerenes. This results into trains of resonances in the Ps formation cross section as a function of the positron beam energy, producing uniform structures in recoil momenta in analogy with classical single-slit diffraction fringes in the configuration space. The prediction opens a hitherto unknown avenue of Ps spectroscopy with nanomaterials.PACS numbers: 34.80. Lx, 36.10.Dr, Following the impact of positrons with matter the formation of exotic electron-positron bound-pair, the positronium (Ps), is a vital process in nature. This channel accounts for as large as half of the positron scattering cross section from simple atoms and molecules [1], as well as an even higher success rate of Ps formation on surfaces and thin films [2]. Other than probing structure and reaction mechanism of matters, the Ps formation is a unique pathway to the electron-positron annihilation process [3,4] with both astrophysical [5] and applied [6] interests. Possible production of Bose-Einstein condensate of Ps has also been predicted [7,8], besides the importance of Ps in diagnosing porous materials [9] as well as in probing bound-state QED effects [10]. Moreover, efficient Ps formation is the precursor of the production of dipositronium molecules [11] and antihydrogen atoms [12,13] required to study the effect of gravitational force on antimatter [14,15].Theoretical investigations to calculate Ps formation cross sections from atomic hydrogen [16][17][18], noble gases [19][20][21], and alkali metals [22,23] However, in spite of such broad landscape of Ps research, little attempt of Ps formation by implanting positrons in nanoparticles, in gas or solid phase, has so far been made, except for a single theoretical study using Na clusters [36]. On the other hand, straddling the line between atoms and condensed matters are clusters and nanostructures that not only have hybrid properties of the two extremes, but also exhibit outstanding behaviors with unusual spectroscopic effects [37]. Formation of a quasi-free electron gas within a finite nanoscopic region of well-defined boundary, as opposed to a longer-range, highly diffused Coulomb-type boundary characteristic of atoms and molecules, is a property of nanosystems which ensures predominant electron capture from localized regions in space. This may lead to diffraction in the capture amplitude, particularly at positron energies that cannot excite plasmon modes. The Ps formation from fullerenes can be singularly attractive to access this diffraction phenomenon due to fullerene's eminent symmetry and stability, and its previous track record of success in spectroscopic experiments [38]. In this communication, we show that the Ps formation amplitude from the positron colliding with C 60 does include a strong diffraction effect, resulting in a system of peaks in the form of broad shape ...

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“…There is an abundance of theoretical investigations in the literature to calculate Ps formation from a wide varieties of target. This includes atomic targets: (i) the hydrogen atom using variants of coupled-channel methods [19,20] and multichannel Schwinger's principle [21]; (ii) noble gas atoms in the distorted-wave [22], the boundary-corrected Born [23], and the relativistic optical potential method [24]; and (iii) alkali metal atoms in the optical potential approach [25] and in the classical trajectory Monte Carlo method when the targets are in Debye plasma environments [26]. Among these studies, ab initio close-coupling calculations, pioneered by Walters and collaborators [27], have in general been very successful [28].…”

Section: Introductionmentioning

confidence: 99%

Molecular-size effects on diffraction resonances in positronium formation from fullerenes

Hervieux

Chakraborty

2019

Phys. Rev. A

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We previously predicted [P. A. Hervieux et al. Phys. Rev. A 95, 020701 (2017)] that owing to predominant electron capture by incoming positrons from the molecular shell, C 60 acts like a spherical diffractor inducing resonances in the positronium (Ps) formation as a function of the positron impact energy. By extending the study for a larger C 240 fullerene target, we now demonstrate that the diffraction resonances compactify in energy in analogy with the shrinking fringe separation for larger slit size in classical single-slit experiment. The result brings further impetus for conducting Ps spectroscopic experiments with fullerene targets, including target-and/or captured-level differential measurements. The ground states of the fullerenes are modeled in a spherical jellium frame of the local density approximation (LDA) method with the exchange-correlation functional based on the van Leeuween and Baerends (LB94) model potential, while the positron impact and Ps formation are treated in the continuum distorted-wave final state (CDW-FS) approximation.

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Positronium formation in collisions between positrons and alkali-metal atoms (Li, Na, K, Rb and Cs) in Debye plasma environments

Cited by 21 publications

References 122 publications

Review of quantum collision dynamics in Debye plasmas

Review of quantum collision dynamics in Debye plasmas

Ubiquitous diffraction resonances in positronium formation from fullerenes

Molecular-size effects on diffraction resonances in positronium formation from fullerenes

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