Measurement of ortho-Positronium Properties in Liquid Scintillators

TL;DR

This study measures ortho-Positronium properties in various liquid scintillators to improve electron-positron discrimination, which is crucial for neutrino detection and particle physics experiments.

Contribution

It provides detailed characterization of o-Ps properties in common scintillators and doped variants, advancing pulse shape discrimination techniques.

Findings

o-Ps properties vary with scintillator type and doping

Doped scintillators retain suitable o-Ps characteristics

Enhanced electron-positron discrimination potential

Abstract

Pulse shape discrimination in liquid scintillator detectors is a well-established technique for the discrimination of heavy particles from light particles. Nonetheless, it is not efficient in the separation of electrons and positrons, as they give rise to indistinguishable scintillator responses. This inefficiency can be overtaken through the exploitation of the formation of ortho-Positronium (o-Ps), which alters the time profile of light pulses induced by positrons. We characterized the o-Ps properties in the most commonly used liquid scintillators, i.e. PC, PXE, LAB, OIL and PC + PPO. In addition, we studied the effects of scintillator doping on the o-Ps properties for dopants currently used in neutrino experiments, Gd and Nd. Further measurements for Li-loaded and Tl-loaded liquid scintillators are foreseen. We found that the o-Ps properties are suitable for enhancing the electron-positron discrimination.