Reconstruction of high-energy shower cores in MATHUSLA

Abstract

In this work, we show the results of a comparative analysis of different reconstruction methods of shower cores produced by Cosmic Rays (CR’s) in a layer of Resistive Plate Chambers (RPC’s) that is under consideration for MATHUSLA (Massive Timing Hodoscope for Ultra-Stable neutraL pArticles). The analysis was performed with Monte Carlo simulations. Extensive air showers were simulated with CORSIKA using the GEISHA and QGSJET-II-04 hadronic interaction models for primary protons and iron nuclei in the energy range from 10 TeV to 100 PeV and zenith angles: θ ≤ 20°. The detector response was simulated with a simplified Python-based program. The location of the shower core was found using the center of mass of the deposited charge distribution, the maximum of the charge distribution, a fit with an exponential function to the projected distributions on the X and Y horizontal directions of the 2D charge distributions, and fits with an exponential and a Nishimura-Kamata-Greisen (NKG) lateral functions to the 3D charge distributions of the RPC. We found that the fits of the X and Y projections with an exponential function and the fits with a NKG function to the 3D signal distributions have a better performance than the other methods.