1,440 research outputs found
Similarity between positronium-atom and electron-atom scattering
We employ the impulse approximation for description of positronium-atom
scattering. Our analysis and calculations of Ps-Kr and Ps-Ar collisions provide
theoretical explanation of the similarity between the cross sections for
positronium scattering and electron scattering for a range of atomic and
molecular targets observed by S. J. Brawley et al. [Science 330, 789 (2010)].Comment: 10 pages, 3 figure
Ps-atom scattering at low energies
A pseudopotential for positronium-atom interaction, based on electron-atom
and positron-atom phase shifts, is constructed, and the phase shifts for Ps-Kr
and Ps-Ar scattering are calculated. This approach allows us to extend the
Ps-atom cross sections, obtained previously in the impulse approximation [Phys.
Rev. Lett. 112, 243201 (2014)], to energies below the Ps ionization threshold.
Although experimental data are not available in this low-energy region, our
results describe well the tendency of the measured cross sections to drop with
decreasing velocity at a.u. Our results show that the effect of the
Ps-atom van der Waals interaction is weak compared to the polarization
interaction in electron-atom and positron-atom scattering. As a result, the Ps
scattering length for both Ar and Kr is positive, and the Ramsauer-Townsend
minimum is not observed for Ps scattering from these targets. This makes Ps
scattering quite different from electron scattering in the low-energy region,
in contrast to the intermediate energy range from the Ps ionization threshold
up to a.u., where the two are similar.Comment: 26 pages, 10 figure
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