Characterization of water-based liquid scintillator for Cherenkov and scintillation separation

TL;DR

This study measures the light yield and timing of water-based liquid scintillators with varying concentrations, demonstrating improved Cherenkov and scintillation light separation, which is promising for large-scale detector applications.

Contribution

It provides detailed measurements of light yield and timing profiles for water-based scintillators, highlighting their potential for enhanced Cherenkov and scintillation separation.

Findings

Light yield is linear with concentration between 1-10%.

Measured time profiles are faster than pure scintillator.

Cherenkov and scintillation separation improves at centimeter scale.

Abstract

This paper presents measurements of the scintillation light yield and time profile for a number of concentration of water-based liquid scintillator, formulated from linear alkylbenzene (LAB) and 2,5-diphenyloxazole (PPO). We find that the scintillation light yield is linear with the concentration of liquid scintillator in water between 1 and 10% with a slope of 127.9+-17.0 ph/MeV/concentration and an intercept value of 108.3+-51.0 ph/MeV, the latter being illustrative of non-linearities with concentration at values less than 1%. This is larger than expected from a simple extrapolation of the pure liquid scintillator light yield. The measured time profiles are consistently faster than that of pure liquid scintillator, with rise times less than 250ps and prompt decay constants in the range of 2.1-2.85ns. Additionally, the separation between Cherenkov and scintillation light is quantified using cosmic muons in the CHESS experiment for each formulation, demonstrating an improvement in separation at the centimeter scale. Finally, we briefly discuss the prospects for large-scale detectors.