Machine Learning-Based Cluster Classification to Suppress Background in a Prototype RPC Detector

TL;DR

This paper introduces a machine learning approach using cluster-level features to effectively distinguish signal from background in RPC detectors, improving accuracy and efficiency in high-energy physics experiments.

Contribution

The study develops and evaluates three classifiers, with XGBoost performing best, demonstrating a practical method for background suppression in RPC detectors.

Findings

XGBoost achieved the best discrimination performance.

Cluster size and temporal-shape features are key discriminants.

Machine learning classifiers effectively suppress background in RPC data.

Abstract

Resistive Plate Chambers (RPCs) are widely used as tracking detectors in many high-energy physics experiments. It has been observed that low-resistive bakelite RPC prototypes frequently exhibit a secondary hit component, appearing as a long tail or an additional peak in the time-correlation spectra relative to the trigger detector. These secondary hits, which affect both the time and spatial resolution, are difficult to distinguish from genuine signals in high-rate environments without an external trigger. As a result, they can significantly degrade track reconstruction efficiency and increase processing time. We present a machine-learning-based strategy to separate signal and background hit clusters using fifteen cluster-level descriptors that encode both statistical properties (histogram mean, width, cluster size) and fit-based parameters (Gaussian-fit mean, width, amplitude, chi^2, NDF) of the time and ADC distributions. Using laboratory data collected from a single-gap low resistive RPC with a three-scintillator master trigger, we trained and evaluated three classifiers-DNN, 1D-CNN, and XGBoost-on balanced signal/background samples. All models demonstrate strong discrimination capability, with XGBoost showing the most robust generalization performance. Feature-importance analysis indicates that cluster size and temporal-shape descriptors are the dominant discriminants. These results highlight that compact, interpretable cluster-level features combined with machine-learning classifiers offer a practical and effective approach to suppress background in self-triggering low resistive RPC detectors.