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

Abstract

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.

To the theory of Ps formation. New interpretation of the lifetime spectrum in water

“…Its simplest semi-phenomenological account was made in (Stepanov et al, 2005b) for interpretation of the Ps formation in acetone-acetic acid solutions, but more strict approach should be based on ambipolar diffusion equations (see Appendix C in Stepanov and Byakov, 2002), which link together concentrations of intrablob particles and local electric field. …”