Extrapolation of Electron-Rare Gas Atom Cross Sections to Zero Energy

O'Malley, Thomas F.

doi:10.1103/physrev.130.1020

Cited by 469 publications

(80 citation statements)

References 30 publications

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“…This result is in very good agreement with the value of −6.527a 0 obtained using original MERT analysis applied to very-low-energy elastic DCSs by Weyhreter et al [13]. Moreover, it is also consistent with A = −6.5a 0 determined by O'Malley [11] from very old TCS by Ramsauer and Kollath [35]. The comparison of e − +Xe scattering lengths determined experimentally or theoretically by different methods is given in Table 2.…”

Section: Total Cross Sectionssupporting

confidence: 78%

“…To the best of our knowledge, only O'Malley [11], Guskov et al [12], Weyhreter et al [13], and Kurokawa et al [14,15] used the original approach to MERT in order to extrapolate some low-energy e − −Xe experimental data down to zero energy. However, except the last paper, these analysis were done long time ago, when few datasets were available.…”

Section: Introductionmentioning

confidence: 99%

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Markov Chain Monte Carlo Effective Range Analysis of Low-Energy Electron Elastic Scattering from Xenon

Fedus

2015

Braz J Phys

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Modified effective range theory formulated as a Bayesian statistical model through the combination with Markov Chain Monte Carlo integration and fitting techniques is used to check the compatibility of different e − −Xe scattering data such as the total cross-sections, the momentum transfer cross-sections, and the differential cross-sections that were determined experimentally in the region of Ramsauer-Townsend minimum. On the basis of this predictive approach, the most probable value of the scattering length, (−6.51 ± 0.05)a 0 , is proposed. The present analysis suggests that the non-relativistic spinless effective range theory is suitable for the description of angular and energy dependencies of e − −Xe elastic scattering cross-sections below the threshold for first inelastic process.

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Section: Total Cross Sectionssupporting

confidence: 78%

Section: Introductionmentioning

confidence: 99%

Markov Chain Monte Carlo Effective Range Analysis of Low-Energy Electron Elastic Scattering from Xenon

Fedus

2015

Braz J Phys

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“…Modified effective range theory (MERT) was developed by O'Malley, Rosenberg and Spruch [1,2] for low-energy scattering of charged particles on neutral polarizable systems in general. O'Malley [3] applied MERT for electron scattering on noble gases, in particular in the region of Ramsauer-Townsend minimum, using early total [4] and momentum transfer [5] experimental cross sections. Haddad and O'Malley [6] used three parameter MERT fit for s-wave phase-shift in electron-argon scattering and Ferch, Granitza and Raith [7] -for Ramsauer minimum in methane.…”

mentioning

confidence: 99%

Applicability of modified effective-range theory to positron-atom and positron-molecule scattering

Idziaszek

Karwasz²

2006

Phys. Rev. A

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We analyze low-energy scattering of positrons on Ar atoms and N2 molecules using Modified Effective-Range Theory (MERT) developped by O'Malley, Spruch and Rosenberg [Journal of Math. Phys. 2, 491 (1961)]. We use formulation of MERT based on exact solutions of Schrödinger equation with polarization potential rather than low-energy expansions of phase shifts into momentum series. We show that MERT describes well experimental data, provided that effective-range expansion is performed both for s-and p-wave scattering, which dominate in the considered regime of positron energies (0.4 -2 eV). We estimate the values of the s-wave scattering lenght and the effective range for e + -Ar and e + -N2 collisions.Electron (and positron) scattering on atoms at very low energies is dominated by polarization forces. Applicability of MERT to low-energy positron scattering was already hypothesized in [2]. However, first measurements of total cross sections for positron scattering at low energies on noble atoms come only from seventies [10,11].The most systematic data for noble atoms, extending down to 0.3 eV were done in WSU Detroit lab, using positrons from a short-lived C 11 radionuclid, with about 0.1 eV energy resolution [11]. Those data indicated clearly a rise of the cross section in the zero energy limit in gases, like He, Ar, H 2 , Kr, Xe, CO 2 , see [11]. Unfortunately, subsequent experiments [12, 13] used Ne 22 source and thick W-vanes positron moderator, thus worsening energy resolution and not allowing to make reliable measurements below 1 eV. To gain in signal, large apertures and strong guiding magnetic fields were used, leading to underestimation of cross sections -some data showed even a fall in the limit of zero energy for highly polarizable targets, like C 6 H 6 [14].Only two of the most recent set-ups reached energies below 1 eV with good signal-to-noise ratio. In San Diego annihilation rates in Ar and Xe were measured, showing a steep rise below 1 eV [15]. In Trento total cross sections in Ar and N 2 were measured [16] with angular resolution better by a factor of 30 than in some previous experiments [12]. Both laboratories confirm the early observations from WSU Detroit on the rise of positron cross sections in the zero-energy limit. Such a rise is also predicted by ab-initio theories [17], see [16] for detailed comparison. A phenomenological attempt to apply MERT-like fit for low-energy cross sections in benzene and cyclohexane was done by Karwasz, Pliszka and Zecca [18].In the present paper we apply MERT to positron total cross sections on argon and nitrogen, using recent experimental data from Trento [16]. We use MERT model based on direct solution of Schrödinger equation with polarization potential as originally proposed by O'Malley, Spruch and Rosenberg [1]. Differently from earlier works, for the p-wave phaseshift we consider not only the polarization potential but contribution from a general-type short range interaction. This allows us to extend the MERT applicability for positrons to energies above 1 e...

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“…O'MALLEY [7] first applied this theory to the elastic scattering of electrons from helium. The author found a fair agreement with the measurement results of RAM-SAUER and KOLLATH [1] for the total scattering cross-section, up to about 4 eV energy.…”

Section: Introductionmentioning

confidence: 98%

Application of a modified effective-range theory to the elastic scattering of low-energy electrons from helium

Orient¹

1966

Acta Physica

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Extrapolation of Electron-Rare Gas Atom Cross Sections to Zero Energy

Cited by 469 publications

References 30 publications

Markov Chain Monte Carlo Effective Range Analysis of Low-Energy Electron Elastic Scattering from Xenon

Markov Chain Monte Carlo Effective Range Analysis of Low-Energy Electron Elastic Scattering from Xenon

Applicability of modified effective-range theory to positron-atom and positron-molecule scattering

Application of a modified effective-range theory to the elastic scattering of low-energy electrons from helium

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