Evaluation of Light Collection from Highly Scattering Media using Wavelength-Shifting Fibers

TL;DR

This study experimentally measures and models the light collection efficiency in opaque scintillators using wavelength-shifting fibers, validating a Monte Carlo simulation and a diffusion model for future detector design optimization.

Contribution

It provides the first direct experimental measurement of light collection efficiency in opaque scintillators and validates models for predicting detector performance.

Findings

Validated Monte Carlo model of light transport

Simple diffusion model reproduces Monte Carlo results

Experimental data informs future detector design

Abstract

Opaque scintillators are designed to have a short scattering length such that scintillation photons are probabilistically confined to a small region of space about their origin. The benefit of this feature is that information on the interaction event topology can be recorded with greater fidelity than in traditional highly transparent media with sensors at large distances from the light production region. Opaque scintillator detectors rely on wavelength-shifting fibers to extract the scintillation light; however, the efficiency of light collection has not yet been directly measured in experiment. We measured the efficiency of light collection as a function of the optical parameters of an opaque liquid and the distance from the origin of the light to the fiber. We use the experimental data to validate a Monte Carlo model of light transport and collection and discuss a simple diffusion model that reproduces the results of Monte Carlo simulation with high fidelity. This combination of validated models has the potential for use in predictions of performance in various designs of future opaque scintillator detectors such as LiquidO.