Polarisation potentials for positron-molecule scattering processes

Gianturco, F. A.; Paioletti, P.; Rodriguez-Ruiz, J. A.

doi:10.1007/bf01437421

Cited by 20 publications

(10 citation statements)

References 36 publications

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“…Experimental data: black circles, Zecca et al [8]; open circles, Hoffman et al [5]; open squares, Charlton et al [7]; small circles, Sullivan et al [9]; solid squares, Zhou et al [15]. Theoretical data: dash-dotted line, Gibson et al [16]; solid line, Armour et al [10]; dotted line, Reid et al [17]; long-short line, Arretche et al [11]; long-short line, Mukherjee et al [12]; dash-dot-dotted line, Danby et al [13], dashed line, Gianturco et al [14]. The vertical dashed line indicates the threshold energy for the formation of positronium at 8.643 eV.…”

Section: Introductionmentioning

confidence: 98%

“…In this energy region there are a broad range of reported results, both experimental and theoretical, which are in apparent disagreement with each other, with the recent results of the Trento group [8] noticeably higher than any other calculation or measurement. Figure 1 shows the state of theoretical and experimental results for the total scattering cross section for positron-H 2 scattering before the present experimental program was undertaken, including a range of theory and experiment [7,[9][10][11][12][13][14][15][16][17]. It does not incorporate our present measurements and the very recent convergent-close-coupling (CCC) theory of Zammit et al [18].…”

Section: Introductionmentioning

confidence: 98%

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Positron scattering from molecular hydrogen

et al. 2013

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We present results for total and partial cross sections for positron scattering from H 2 . The total scattering and positronium formation cross sections are reported between 0.5 and 200 eV. Total quasielastic and inelastic scattering cross sections are reported for energies between the positronium formation threshold and 50 eV, with quasielastic differential scattering cross sections reported at 1, 3, 5, 7, and 10 eV. Our results are compared with previous work, both experimental and theoretical, with particular attention paid to the region below the positronium formation threshold, where there are apparent discrepancies in previous work. A discussion of possible reasons for discrepancies between this and previous work is presented, including a focus on known systematic effects in the experimental results.

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Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 98%

Positron scattering from molecular hydrogen

et al. 2013

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“…2 show a rise in the low energy limit, contrasting with other experimental data [11][12][13][14] and also with some theories [15][16][17][18][19]. The most probable reason for such underestimation of cross-sections in experiments is so-called angular resolution error.…”

Section: Methodsmentioning

confidence: 74%

“…2. Comparison of present cross-sections for positron scattering on nitrogen with other experiments [11][12][13][14] and theories [15][16][17][18][19]. For present data different experimental runs are shown by different symbols.…”

Section: Methodsmentioning

confidence: 74%

Positron Scattering on Atoms and Molecules in the Limit of Low Energy

et al. 2006

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Starting from experimental cross-sections for positron scattering in argon and nitrogen, we examine different energy ranges. In the zero-energy limit the cross-section falls with energy and can be described by modified effective range theory for polarization potential. In a few eV range the cross-sections are constant vs. energy. As far as it is possible to force the elastic scattering phase shifts in a way that both experimental differential cross-sections are reproduced and the total cross-section remains constant in energy, such a model lacks the physical justification. Only the virtualpositronium model, developed recently by Gribakin, reproduces a constant dependence of the total cross-section in a few eV energy range.

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“…This is sufficient as long as the energy E remains smaller than the centrifugal barrier, that for l = 2 has height of 9E * . The total elastic cross-section σ(k) = 4πk −2 l sin 2 η l (k) is determined from the phase shifts (9) and (12), with ν and m evaluated numerically, using the procedure described in Appendices A and B.…”

Section: Mert Analysis Of Low-energy Electron Scatteringmentioning

confidence: 99%

Modified effective-range theory for low energy ${\sf e}$ -N2 scattering

Idziaszek

Karwasz²

2009

Eur. Phys. J. D

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We analyze the low-energy e-N2 collisions within the framework of the Modified-Effective Range Theory (MERT) for the long-range potentials, developed by O'Malley, Spruch and Rosenberg [Journal of Math. Phys. 2, 491 (1961)]. In comparison to the traditional MERT we do not expand the total crosssection in the series of the incident momentum k, but instead we apply the exact analytical solutions of the Schrödinger equation for the long-range polarization potential, as proposed in the original formulation of O'Malley et al.. This extends the applicability of MERT up to few eV regime, as we confirm using some simplified model potential of the electron-molecule interaction. The parameters of the effective-range expansion (i.e. the scattering length and the effective range) are determined from experimental, integral elastic cross sections in the 0.1 -1.0 eV energy range by fitting procedure. Surprisingly, our treatment predicts a shape resonance that appears slightly higher than experimentally well known resonance in the total cross section. Agreement with the experimentally observed shape-resonance can be improved by assuming the position of the resonance in a given partial wave. Influence of the quadrupole potential on resonances is also discussed: we show that it can be disregarded for N2. In conclusion, the modified-effective range formalism treating the long-range part of the potential in an exact way, reproduces well both the very low-energy behavior of the integral cross section as well as the presence of resonances in the few eV range.

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Polarisation potentials for positron-molecule scattering processes

Cited by 20 publications

References 36 publications

Positron scattering from molecular hydrogen

Positron scattering from molecular hydrogen

Positron Scattering on Atoms and Molecules in the Limit of Low Energy

Modified effective-range theory for low energy ${\sf e}$ -N2 scattering

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