An IACT direction reconstruction method suitable for optimizing Cherenkov telescope layouts

Problem The angular resolution of a gamma-ray detector is crucial for the detailed study of gamma-ray sources. The imaging atmospheric Cherenkov technique is used in ground-based gamma-ray astronomy to detect and study high-energy gamma rays from astrophysical sources. It used an array of several telescopes to detect Cherenkov photons in an air shower. Optimizing the location of the telescopes is crucial for large-area Cherenkov telescopes. Currently, the optimization procedure typically involves conducting a full simulation for each candidate layout and comparing the performance between them. This process demands significant computing resources and is time-consuming. It would be highly beneficial to have a method that can quickly predict the performance of an array.
Methods This study introduces a direction reconstruction method based on the maximum likelihood method. The input of this method is the probability distribution of the shower detection plane.
Results The performance of the method in this study closely resembles that of the traditional method at around 1 TeV, with possible superior performance observed at higher energies. The angular and core position resolution of this method can be accurately predicted using a toy Monte Carlo approach with a precision of 10% below 10 TeV.
Conclusion A new direction reconstruction method was introduced in this study, and it can rapidly predict the angular resolution for different layouts of the array, making it suitable for optimizing Cherenkov telescope layouts.