Experimental determination of the scattering length for positron scattering from krypton

Zecca, Antonio; Chiari, Luca; Trainotti, Emanuele; Fursa, Dmitry V.; Bray, Igor; Brunger, M. J.

doi:10.1140/epjd/e2011-20333-7

Cited by 37 publications

(77 citation statements)

References 22 publications

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“…Helium and neon display close scattering lengths in the present calculation, with the result for neon in good agreement with previous many-body theory calculations [23], although somewhat lower than other theoretical predictions [40,52,54]. For argon and krypton, there is close accord between the present manybody theory, polarized orbital [52], and CCC [40] calculations, and the experimental results of Zecca et al [34,35]. The scattering length increases across the noble-gas atom sequence, giving rise to a virtual s-wave level for xenon with the energy of approximately 2 meV.…”

Section: B Scattering Lengthssupporting

confidence: 91%

Positron scattering and annihilation on noble-gas atoms

2014

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Positron scattering and annihilation on noble gas atoms is studied ab initio using many-body theory methods for positron energies below the positronium formation threshold. We show that in this energy range the many-body theory yields accurate numerical results and provides a nearcomplete understanding of the positron-noble-gas-atom system. It accounts for positron-atom and electron-positron correlations, including the polarization of the atom by the positron and the nonperturbative process of virtual positronium formation. These correlations have a large effect on the scattering dynamics and result in a strong enhancement of the annihilation rates compared to the independent-particle mean-field description. Computed elastic scattering cross sections are found to be in good agreement with recent experimental results and Kohn variational and convergent close-coupling calculations. The calculated values of the annihilation rate parameter Z eff (effective number of electrons participating in annihilation) rise steeply along the sequence of noble gas atoms due to the increasing strength of the correlation effects, and agree well with experimental data.

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Section: B Scattering Lengthssupporting

confidence: 91%

Positron scattering and annihilation on noble-gas atoms

2014

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“…Indeed, the discrepancy is nearly 35% at about 20 eV. We were a little surprised by this result, as previous studies by the two groups on argon, 41,71 krypton, 42,72 and xenon 73,74 had shown a quite satisfactory level of accord between their "uncorrected" TCS. Indeed, Zecca et al 69 noted that the angular discrimination of the Trento apparatus is comparable to that of the present spectrometer and since both independent measurements were conducted at the same temperature (∼24 ± 2…”

Section: A Total Cross Sectionsmentioning

confidence: 58%

Total, elastic, and inelastic cross sections for positron and electron collisions with tetrahydrofuran

Chiari

Anderson

Tattersall

et al. 2013

The Journal of Chemical Physics

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We present total, elastic, and inelastic cross sections for positron and electron scattering from tetrahydrofuran (THF) in the energy range between 1 and 5000 eV. Total cross sections (TCS), positronium formation cross sections, the summed inelastic integral cross sections (ICS) for electronic excitations and direct ionization, as well as elastic differential cross sections (DCS) at selected incident energies, have been measured for positron collisions with THF. The positron beam used to carry out these experiments had an energy resolution in the range 40-100 meV (full-width at half-maximum). We also present TCS results for positron and electron scattering from THF computed within the independent atom model using the screening corrected additivity rule approach. In addition, we calculated positron-impact elastic DCS and the sum over all inelastic ICS (except rotations and vibrations). While our integral and differential positron cross sections are the first of their kind, we compare our TCS with previous literature values for this species. We also provide a comparison between positron and electron-impact cross sections, in order to uncover any differences or similarities in the scattering dynamics with these two different projectiles.

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“…As a standard practice in our laboratory, in order to check for the validity of our techniques and procedures, before any experiment on a new target is started we make preliminary validation measurements using targets for which the positron scattering TCSs are considered well known. Such well-characterized systems might be drawn from the noble gases [20][21][22] and molecular nitrogen [3].…”

Section: Methodsmentioning

confidence: 99%