Low-Afterglow, High-Refractive-Index Liquid Scintillators for Fast-Neutron Spectrometry and Imaging Applications

TL;DR

This paper investigates low-afterglow, high-refractive-index liquid scintillators optimized for fast-neutron detection and imaging, using oxygen quenching and advanced photon counting techniques to improve performance.

Contribution

It introduces new liquid scintillator formulations with suppressed afterglow and high refractive index, employing oxygen quenching and TCSPC for characterization.

Findings

Oxygen enrichment effectively reduces afterglow in liquid scintillators.

High refractive index liquids suitable for fiber-based neutron imaging were identified.

The TCSPC method provides detailed glow curve analysis of scintillator performance.

Abstract

For ion and neutron spectrometry and imaging applications at a high intensity pulsed laser facility, fast liquid scintillators with very low afterglow are required. Furthermore, neutron imaging with fiber (or liquid-core) capillary arrays calls for scintillation materials with high refractive index. To this end, we have examined various combinations of established mixtures of fluors and solvents, that were enriched alternatively with nitrogen or oxygen. Dissolved molecular oxygen is known to be a highly effective quenching agent, that efficiently suppresses the population of the triplet states in the fluor, which are primarily responsible for the afterglow. For measuring the glow curves of scintillators, we have employed the time-correlated single photon counting (TCSPC) technique, characterized by high dynamic range of several orders of magnitude in light intensity. In this paper we outline the application for the fast scintillators, briefly present the scintillation mechanism in liquids, describe our specific TCSPC method and discuss the results.