Precise Laser Energy Measurement for the Calibration of LHAASO-WFCTA

The Large High Altitude Air Shower Observatory (LHAASO) is a major scientific research facility focused on cosmic ray observation. The entire array consists of four types of detector arrays, one of which is the Wide Field-of-view Cherenkov Telescope Array (WFCTA). The WFCTA is designed to achieve precise measurements of the cosmic ray energy spectrum across the range of 1013 eV to 1018 eV. A pivotal component of the Cherenkov telescope is its laser calibration system, which currently comprises five fixed laser units employing an end-to-end calibration method to ascertain the calibration coefficients for individual telescopes in response to photon detection. This paper elucidates the results of the relative calibration and performance testing of the energy sensor, which underpin the routine operation of the laser calibration system.