Gamma/hadron discriminant variables in application to high-energy cosmic-ray air showers

TL;DR

This paper investigates and compares trace-based and total-signal-based variables derived from detector signals to improve gamma/hadron primary particle discrimination in high-energy cosmic-ray air showers, using simulations at 10^17.5 eV.

Contribution

It introduces and evaluates trace-based discriminant variables derived from signal time distributions, offering a potentially more effective method for primary particle identification in cosmic-ray experiments.

Findings

Trace-based variables show promise for gamma/hadron discrimination.

Comparison indicates potential advantages over total-signal-based variables.

Variables are suitable for real data application in ground-based cosmic-ray observatories.

Abstract

Identification of primary cosmic rays on an event-by-event basis is a much-desired capability of cosmic-ray observatories. Several cosmic-ray air-shower experiments use so-called photon tags for gamma hadron primary particle discrimination. These photon tag variables are derived from the total signals measured by an array of detectors and are correlated with the total number of muons in the air shower. In this work, variables based on time distribution of signals in detectors (trace-based discriminant variables) are studied and compared to total-signal-based variables. This study relies on simulated high-energy cosmic-ray air showers with energies around 10^17.5eV. Since the variables discussed are derived from total signals and their time traces, which can be directly measured in real data, they are suitable for use as discriminant variables in the real ground-based cosmic ray experiments.