Probing atmospheric effects using GRAPES-3 plastic scintillator detectors

The GRAPES-3 extensive air shower (EAS) array has been designed to study cosmic rays from 10 ^13 –10 ^16 eV. It employs 400 scintillator detectors spread across 25,000 m ^2 , mainly of cone-type and fiber-type, each covering a 1 m ^2 area. These detectors record EAS particle densities and arrival times, which are crucial for determining primary particle energy and direction. A decade (2013–2022) of EAS data is analyzed to investigate the dependence of particle densities on ambient temperature and atmospheric pressure. Notably, ambient temperature exhibits a delayed response, with a more pronounced delay in fiber-type detectors, while cone-type detectors exhibit a higher observed temperature coefficient. In contrast, atmospheric pressure instantly and uniformly affects both detector types, with Monte Carlo simulations backing the observed pressure coefficient. These findings established a reliable pressure coefficient for EAS within this distinctive energy range and contributed to the refinement of correction algorithms, ultimately improving particle density precision for more accurate shower parameter estimates.