Effect of dielectric screening on positronium formation in acetone-acetic acid polar solvent blends

The influence of polarization of a medium in the vicinity of the positron-electron pair produced at the end of a fast-positron track on the formation of positronium (Ps) was considered. Weakening interaction between the positron and electron, polarization leads to a decrease in the Ps formation probability. The transience of Ps formation requires that the time delay of medium polarization should be taken into account. In turn, the magnitude of dielectric screening in acetone-acetic acid mixtures strongly depends on the ratio between the amounts of polar monomeric acetic acid and its nonpolar dimer. Sequentially taking account of these effects, it is possible to explain both the complex behavior of the Ps yield and the dependence of dielectric permittivity of the mixture on its composition.Translated from Khimiya Vysokikh Energii, Vol. 39, No. 2, 2005, pp. 153–159.Original Russian Text Copyright © 2005 by Stepanov, Byakov, Stepanova.This revised version was published online in April 2005 with a corrected cover date.