Effects of local heating and premelting in the terminal part of the e$^+$ track

TL;DR

This paper investigates how local heating and premelting caused by positron interactions affect the lifetime of ortho-positronium in alcohols near their melting points, revealing temperature-dependent behaviors.

Contribution

It introduces a model describing the temperature dependence of ortho-positronium lifetime in alcohols considering local heating and premelting effects.

Findings

Positron-induced local heating influences positronium lifetime.

The model explains temperature-dependent lifetime variations.

Premelting effects are significant near phase transition temperatures.

Abstract

Due to the ionizations promoted by the slowing down of energetic positron and subsequent ion-electron recombinations, positron releases up to 1 keV in the terminal blob region [1]. After all this energy converts into heat. This local heating effect makes the medium to heat up and melt, especially at the region where the bulk temperature of the medium is close (but slightly below) the phase transition temperature. In this case this effect leads to a peculiar temperature dependence of the lifetime of the long-lived LT spectra component. We introduce a model to describe the temperature behaviour of the ortho-positronium lifetime for three simple alcohols (methanol, ethanol and butanol) at the melting range.