New time-based parameters to enhance gamma-ray and hadron discrimination for the ASTRI Mini-Array

The ASTRI Mini-Array is an international project to build and operate an array of nine 4-m diameter Imaging Atmospheric Cherenkov Telescopes (IACT) at the Observatorio del Teide (Tenerife, Spain). The array has been designed to perform deep galactic and extragalactic gamma-ray sky observations in the 1-200 TeV energy range. As of today, the first telescope ASTRI-1 is fully operative, and in its commissioning phase. In the effort of improving the sensitivity of the array, particularly in discriminating between gamma-ray- and hadron-induced showers, we are investigating whether the temporal evolution of the shower images, as recorded by the pixel time tag, can provide additional discriminatory power beyond the traditional morphological parameters. We have developed and tested a set of parameters and through extensive testing, we have identified a subset of them that exhibit good discriminatory efficacy. In our preliminary analysis, combining the time parameters with the standard morphological ones has demonstrated a significant improvement in hadron rejection, especially at the lower end of the energy detection range (below 1 TeV), and a definite boost in the single telescope performance. Here we show also the distributions of this new set of parameters in the ASTRI-1 data taken in the November 2024 – February 2025 campaign and how they compare with the simulations.