Low-energy elastic and inelastic scattering of positrons from argon

Boadle, Roisin; Babij, T. J.; Machacek, Joshua; McEachran, R P; Sullivan, James P.; Buckman, Stephen

doi:10.1103/physreva.93.022712

Cited by 6 publications

(6 citation statements)

References 20 publications

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“…values for the cutoff radii. The comparison with the experimental data clearly favours the highest r c .The results for the χ 2 -FDCS model are reported taking as reference the FDCS data of Boadle et al[23].…”

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confidence: 56%

“…Only recently in the history of the field has a set of absolute differential cross sections (DCSs) for positron scattering by noble gas atoms been reported in the literature. More precisely, a set of absolute folded differential cross sections (FDCSs) was measured for Kr [21], Xe [22] and Ar [23]. The experimental data were systematically compared to the relativistic optical potential [24] and the CCC methods [25], with general good agreement between theory and experimental results.…”

Section: Introductionmentioning

confidence: 97%

“…The same as in table 7 but for Ar taking as reference the FDCSs of Boadle et al[23]. Only the values corresponding to the lowest cutoff value are considered because they provide the lower χ 2 .…”

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confidence: 99%

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Semiempirical models for low energy positron scattering by Ar, Kr and Xe

Arretche

Barp

Scheidt

et al. 2019

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

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Positron scattering by Ar, Kr and Xe was investigated considering two well-established semiempirical potentials with different descriptions of the asymptotic positron–atom scattering potential. Exploring the ultimate nature of semiempirical formulations, two independent semiempirical models were studied. In the first model, the potential parameters were fixed to reproduce the experimental values of the positron–atom scattering length, while, in the second, they were tuned to better fit experimental absolute folded differential cross sections through a χ2 approach. Results showed that the introduction of higher order polarisabilities and hyperpolarisabilities considerably improved the description of the forward scattering and the total and grand-total experimental low energy cross sections.

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mentioning

confidence: 56%

Section: Introductionmentioning

confidence: 97%

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Semiempirical models for low energy positron scattering by Ar, Kr and Xe

Arretche

Barp

Scheidt

et al. 2019

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

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“…A number of FDCS have been reported for positron scattering from noble gases at energies below the threshold for the first inelastic scattering channel [1,[4][5][6][7]. These data have been fitted for the case n e =2, n o =1 to determine the s-, p-and d-wave phase shifts using Ali-Fraser terms up to an l of 199.…”

Section: Resultsmentioning

confidence: 99%

“…where C is a constant, E is the scattering energy and E || is the parallel energy [1,2]. A knowledge of the constant C allows the absolute elastic differential cross section to be determined from a parallel-energy loss spectrum [1,[4][5][6][7]. Equation (19) can be rewritten in terms of cos 2 θ using E Ecos .…”

Section: Extension To I(θ)mentioning

confidence: 99%

Partial wave analysis for folded differential cross sections

Machacek¹,

McEachran

2018

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

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The value of modified effective range theory (MERT) and the connection between differential cross sections and phase shifts in low-energy electron scattering has long been recognized. Recent experimental techniques involving magnetically confined beams have introduced the concept of folded differential cross sections (FDCS) where the forward (θπ/2) and backward scattered (θπ/2) projectiles are unresolved, that is the value measured at the angle θ is the sum of the signal for particles scattered into the angles θ and π−θ. We have developed an alternative approach to MERT in order to analyse low-energy folded differential cross sections for positrons and electrons. This results in a simplified expression for the FDCS when it is expressed in terms of partial waves and thereby enables one to extract the first few phase shifts from a fit to an experimental FDCS at low energies. Thus, this method predicts forward and backward angle scattering (0 to π) using only experimental FDCS data and can be used to determine the total elastic cross section solely from experimental results at low-energy, which are limited in angular range.

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