Interpretable machine learning approach for electron antineutrino selection in a large liquid scintillator detector

TL;DR

This paper presents an interpretable machine learning model, specifically a neural network, to enhance electron antineutrino event selection in large liquid scintillator detectors like JUNO, improving efficiency and providing insights into decision-making.

Contribution

It introduces the first interpretable ML approach for reactor neutrino event selection, demonstrating improved efficiency and interpretability over traditional cut-based methods.

Findings

ML model improves event selection efficiency

Allows retention of edge events with high background

Provides insights into model decision processes

Abstract

Several neutrino detectors, KamLAND, Daya Bay, Double Chooz, RENO, and the forthcoming large-scale JUNO, rely on liquid scintillator to detect reactor antineutrino interactions. In this context, inverse beta decay represents the golden channel for antineutrino detection, providing a pair of correlated events, thus a strong experimental signature to distinguish the signal from a variety of backgrounds. However, given the low cross-section of antineutrino interactions, the development of a powerful event selection algorithm becomes imperative to achieve effective discrimination between signal and backgrounds. In this study, we introduce a machine learning (ML) model to achieve this goal: a fully connected neural network as a powerful signal-background discriminator for a large liquid scintillator detector. We demonstrate, using the JUNO detector as an example, that, despite the already high efficiency of a cut-based approach, the presented ML model can further improve the overall event selection efficiency. Moreover, it allows for the retention of signal events at the detector edges that would otherwise be rejected because of the overwhelming amount of background events in that region. We also present the first interpretable analysis of the ML approach for event selection in reactor neutrino experiments. This method provides insights into the decision-making process of the model and offers valuable information for improving and updating traditional event selection approaches.