Reconstruction of coincident EAS events between LHAASO and ENDA

In the investigation of the ”knee” region within the cosmic ray energy spectrum, energy determination and composition separation are of paramount importance. The Electron-Neutron Detector Array (ENDA) is designed to detect not only electrons in the proximity of the extensive air shower (EAS) core, but also thermal neutrons generated in the ground by secondary hadrons which constitute the ”backbone” of EAS and carry vital information regarding the primary cosmic rays. ENDA-64, consisting of 64 detectors, is employed inside the Large High Altitude Air Shower Observatory (LHAASO). Hybrid detection of EAS using LHAASO and ENDA can provide a full secondary particle measurement of EAS including electrons, muons, atmospheric Cherenkov light, and hadrons, exhibiting a unique capacity for separating primary components and accurately measuring energy. ENDA-64 consists of 4 clusters, and each cluster is configured as a 4×4 matrix of 16 detectors. The inter-detector distance is approximately 4.5 m, compared to 15 m for the electromagnetic component detectors (ED) of LHAASO-KM2A. Moreover, ENDA-64 can measure electrons over a higher dynamic range than ED. By selecting EAS events with cores falling inside ENDA, a comprehensive analysis of coincident events between LHAASO-KM2A (farther from the EAS core) and ENDA (closer to the core) enables full lateral electron distribution acquisition, ultimately enhancing the precision of core position, size, and age construction.