Layout optimization and performance analysis of large array of imaging atmospheric Cherenkov telescopes*

Abstract The large array of imaging atmospheric Cherenkov telescopes (LACT) is a planned array of 32 Cherenkov telescopes, each featuring 6-m diameter mirrors, to be constructed at the LHAASO site. This study focused on optimizing the array layout and analyzing the performance of LACT. Two observation modes were examined: large zenith angle observations for ultra-high energy events and small zenith angle observations for lower energy thresholds. For large zenith angles (60°), simulations indicate that an 8-telescope subarray can achieve an effective area of with excellent angular resolution. For small zenith angles, we optimized the layout of 4-telescope cells and the full 32-telescope array. The energy threshold of the full array is approximately 200 GeV, which is particularly crucial for studying transient phenomena such as gamma-ray bursts (GRBs) and active galactic nuclei (AGNs). This study provides essential guidance for finalizing the LACT layout design and estimating performance under various observational conditions. It also highlights the potential of LACT for conducting deep observations of ultra-high energy γ -ray sources, performing morphological studies of PeVatrons, and advancing time-domain γ -ray astronomy.