Layout optimization and Performance of Large Array of imaging atmospheric Cherenkov Telescope (LACT)

TL;DR

This paper analyzes the layout optimization and performance of the LACT array, demonstrating its potential for high-energy gamma-ray observations, transient phenomena, and deep astrophysical studies under various observational modes.

Contribution

It provides the first detailed layout optimization and performance analysis of the LACT array for different zenith angles and energy thresholds.

Findings

An 8-telescope subarray achieves 3 km^2 effective area at 60° zenith angle.

Full 32-telescope array has a threshold of about 200 GeV.

Optimized layouts enhance LACT's capabilities for high-energy and transient gamma-ray astronomy.

Abstract

Large Array of imaging atmospheric Cherenkov Telescope (LACT) is an array of 32 Cherenkov telescopes with 6-meter diameter mirrors to be constructed at the LHAASO site. In this work, we present a study on the layout optimization and performance analysis of LACT. We investigate two observation modes: large zenith angle observations for ultra-high energy events and small zenith angle observations for lower energy thresholds. For large zenith angles (60{\deg}), simulations show that an 8-telescope subarray can achieve an effective area of $3 ~\rm km^2$ and excellent angular resolution. For small zenith angles, we optimize the layout of 4-telescope cells and the full 32-telescope array. The threshold of the full array is about $200~\rm GeV$, which is particularly crucial for studying transient phenomena, including gamma-ray bursts (GRBs) and active galactic nuclei (AGNs). This study provides important guidance for the final LACT layout design and performance estimates under different observational conditions, demonstrating LACT's potential for deep observations of ultra-high energy \gray sources and morphological studies of PeVatrons, as well as time-domain \gray astronomy.