Speaker
Description
The camera of an atmospheric Cherenkov telescope measures the intensity and profile of Cherenkov light that reaches the focal plane via reflective mirrors. As a key instrument for measuring Cherenkov light at the focal plane in WFCTA observations, the SiPM camera can operate normally under moonlight conditions; however, moonlight introduces significant fluctuations in night-sky background light, and the gain of the SiPM detectors is highly sensitive to ambient temperature and background light intensity. Currently, the WFCTA experiment employs an LED light source installed at the center of the reflector and flashing at a frequency of 3 Hz to perform real-time gain calibration for the SiPMs inside the camera, with an uncertainty of less than 2.6% for this calibration method. To further improve the reliability of WFCTA observation data, this study proposes a novel camera calibration method based on the relationship between SiPM gain and background light intensity, and conducts a cross check with the LED calibration method. In addition, a new calibration scheme suitable for LACT SiPM cameras is proposed by combining night-sky background light calibration with LED light source calibration. This method obtains the absolute gain of calibration pixels using night-sky background light, and calibrates the number of photons incident on the camera surface from the reference LED via the calibration pixels, thereby accomplishing the absolute calibration of SiPM gains within the camera.
