Characterization of the scintillation response of water-based liquid scintillator to alpha particles, and implications for particle identification

TL;DR

This paper measures the scintillation response of water-based liquid scintillator to alpha particles, providing data for simulation models to improve particle identification in large neutrino detectors across various scales.

Contribution

It presents new measurements of scintillation light yield and timing profiles for water-based scintillators in response to alpha radiation, informing future detector simulations.

Findings

Alpha/beta discrimination improves with higher scintillation concentration.

Achieves over 80% alpha rejection at 90% beta acceptance in 10% water-based scintillator.

Demonstrates timing-based particle identification at multiple detector scales.

Abstract

Next-generation large-scale neutrino detectors, from Eos, at the 1 tonne scale, to Theia, at the 10s-of-ktonne scale, will utilize differences in both the scintillation and Cherenkov light emission for different particle species to perform background rejection. This manuscript presents measurements of the scintillation light yield and emission time profile of water-based liquid scintillator samples in response to $\alpha$ radiation. These measurements are used as input to simulation models used to make predictions for future detectors. In particular, we present the timing-based particle identification achievable in generic water-based scintillator detectors at the 4 tonne, 1 ktonne, and 100 ktonne scales. We find that $\alpha$/$\beta$ discrimination improves with increasing scintillation concentration and we identify better than 80% $\alpha$ rejection for 90% $\beta$ acceptance in 10% water-based liquid scintillator, at the 4 tonne scale.