ANALYSIS OF POSSIBLE SCATTERING PROCESSES FOR BLOCH POSITRONIUM IN IONIC CRYSTALS AT ELEVATED TEMPERATURES |
| I.V. Bondarev The Institute of Nuclear Problems, The Belarusian State University Bobruiskaya Str. 11, 220050 Minsk, Belarus |
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| The role of nonpolar optic phonon scattering and of umklapp acoustic phonon scattering is analyzed for a delocalized positronium atom in ionic crystals at elevated temperatures. At temperatures above which they become essential both of these scattering mechanisms contribute to the imaginary self-energy of positronium renormalizing its acoustic deformation potential constant. It was such a renormalization that was recently observed experimentally for delocalized positronium in MgF2 crystal. We put forward the theoretical explanation of these experiments based upon the model of nonpolar optic phonon scattering of positronium. An effect analogous to that observed in MgF2 is predicted for crystalline quartz above the temperature of (α-β)-phase transition. |
| DOI: 10.12693/APhysPolA.99.337 PACS numbers: 78.70.Bj, 71.60.+z, 71.38.+i, 36.10.Dr |