The evidence of quasi-free positronium state in GiPS-AMOC spectra of glycerol

TL;DR

This study identifies a quasi-free positronium state in glycerol using Gamma-induced positron spectroscopy, revealing an intermediate state that influences annihilation spectra and serves as a precursor to trapped positronium states.

Contribution

The paper introduces the concept of a quasi-free positronium state in glycerol and models its properties, supported by experimental AMOC spectra analysis.

Findings

Quasi-free Ps accounts for less than 5% of total annihilations.

The shape of the s(t) curve requires the inclusion of the quasi-free Ps state.

Quasi-free Ps acts as a precursor to trapped para- and ortho-positronium.

Abstract

We present the results of processing of Age-Momentum Correlation (AMOC) spectra that were measured for glycerol by the Gamma-induced positron spectroscopy (GiPS) facility. Our research has shown that the shape of experimental s(t) curve cannot be explained without introduction of the intermediate state of positronium (Ps), called quasi-free Ps. This state yields the wide Doppler line near zero lifetimes. We discuss the possible properties of this intermediate Ps state from the viewpoint of developed model. The amount of annihilation events produced by quasi-free Ps is estimated to be less than 5% of total annihilations. In the proposed model, quasi-free Ps serves as a precursor for trapped Ps of para- and ortho-states.