Absolute Calibration Of LHAASO WFCTA Camera Based On LED
Abstract
The main scientific goal of the LHAASO WFCTA experiment is to measure the cosmic ray energy spectra and composition from 10 TeV to 1 EeV. Cherenkov photons in the extensive air shower measured by the SiPM camera of Cherenkov telescopes can be used to reconstruct the cosmic ray energy. The absolute calibration of the camera is a crucial step to achieve the accurate measurement of the cosmic ray energy spectrum. A multi-wavelength cylindrical illuminator based on LEDs is developed and mounted inside the telescope to calibrate and monitor the camera, and the illuminator's stability is better than 0.5% under the temperature variation from -26 to 26 °C. A portable probe with a single photoelectron resolution of 21.6% is developed. After calibration by National Institute of Metrology, China (NIM), the probe is taken to the LHAASO site to measure the absolute photon density of the cylindrical illuminator inside the telescope. Based on the illuminator with known photon density, the photon conversion factor of the camera can be calibrated, and the overall calibration uncertainty is less than 2.6%.
Recommended Citation
"Absolute Calibration Of LHAASO WFCTA Camera Based On LED," Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment, vol. 1021, article no. 165824, Elsevier, Jan 2022.
The definitive version is available at https://doi.org/10.1016/j.nima.2021.165824
Department(s)
Physics
Keywords and Phrases
Calibration; Cylindrical illuminator; LHAASO-WFCTA; Photons to electronic signal; Relative photon distribution; SiPM camera
International Standard Serial Number (ISSN)
0168-9002
Document Type
Article - Journal
Document Version
Citation
File Type
text
Language(s)
English
Rights
© 2025 Elsevier, All rights reserved.
Publication Date
01 Jan 2022
Comments
National Natural Science Foundation of China, Grant 11205126