Nonpolar optical scattering of positronium in magnesium fluoride

TL;DR

This paper analyzes how temperature affects the momentum distribution of delocalized positronium in magnesium fluoride, using an optical deformation-potential scattering model to determine coupling constants and phase transition sensitivities.

Contribution

It introduces a model for positronium optical scattering in MgF₂ and measures the optical deformation-potential coupling constant, revealing phase transition effects.

Findings

Determined the optical deformation-potential coupling constant $D_{o}$ as $(1.8\u00b10.3) imes10^{9}$ eV/cm.

Showed Ps momentum distribution sensitivity to second-order phase transitions.

Identified differences in optical deformation-potential scattering across crystal phases.

Abstract

We report the results of the analysis of the temperature broadening of the momentum distribution of delocalized Positronium (Ps) in Magnesium Fluoride in terms of optical deformation-potential scattering model (long-wavelength optical phonons). The Ps optical deformation-potential coupling constant $D_{o}$ in MgF$_{2}$ has been determined to be $(1.8\pm0.3)\times10^{9}$ eV/cm. We also show that the Ps momentum distribution is sensitive to second-order phase transitions in those crystals where optical deformation-potential scattering is allowed in one and forbidden in another crystalline phase.