Absolute calibration of LHAASO WFCTA camera based on LED

F Aharonian,Long Chen,B Liu,S.S Zhang,L.Y Wang,K Levochkin,J Liu,J.S Liu,P Pattarakijwanich,X.L Chen,W Zeng,H.D Liu,Z.H Wang,P.F Zhang,X.R Li,H.G Wang,M.Y Liu,Lu Zhang,M.J Chen,J.C Wang,X.J Wang,T.L Chen,W Liu,Xin Li,Y.F Zhang,M Heller,V Stepanov,C Hou,J.L Liu,Y.M Ye,Yong Zhang,M.L Chen,H.B Li,B.M Chen,W Wang,D Ruffolo,D Della Volpe,M Zha,Zhe Cao,S.Z Chen,R Zhang,J.W Zhang,Y Zheng,S.H Chen,Y.T Fu,J Chen,C Liu,L.P Wang,H.C Li,H Wang,Li Zhang,Y.J Wang,L Xue,Y.L Zhang,Y Wang,Y.Z Li,J Fang,V Rulev,B.B Li,H Liu,D Liu,S.R Zhang,J.L Zhang,Danzengluobu Danzengluobu,H.M Zhang,J.Y Liu,D Kuleshov,Zheng Wang,W Mitthumsiri,K Jiang,X.G Wang,E.S Chen,J.S Wang,H.Y Zhang,Q.H Chen,Y.D Wang,W.L Li,Zhuo Li,B D’Ettorre Piazzoli,S.M Liu,T Montaruli,Y Liu,Y.N Liu,J Xia,Zhe Li,L.X Zhang,J Li,H Cai,Zhen Wang,P.P Zhang,C Wang,R.Y Liu,Liang Chen,A Masood,Z.X Wang,X Zhang,Z.X Liu,B.B Zhang,Axikegu Axikegu,Cheng Li,D Bastieri,F Li,H Zhou,X.P Zhang,L Shao,R.N Wang,Yi Zhang,H.Y Li,Y.P Wang,A Sáiz,Y Li,Y He,B.D Wang,Y Chen,F Zheng,W X Wu ,En‐Wei Liang ,Yu V Stenkin ,Xiaohua Ma ,Z Tang ,J Mao ,Qi An ,Y L Feng ,Li Feng ,Y K Hor ,S J Lin ,Chao Jin ,Y J Wei ,Haiyong Gan ,Fei Ji ,X Wu ,D L Xu ,Dahai Yan ,Y Y Guo ,Y C Nan ,Junjiang He ,Kai-Kai Duan ,Z J Jiang ,Bin Ma ,Haibing Hu ,Jiafeng Chang ,Fulai Guo ,D X Xiao ,Y Bai ,M Y Qi ,Ke Fang ,Fang Yang ,Z Y You ,Xiuyuan Wang ,X J Bi ,C Y Wu ,Zhao Liu ,M M Ge ,Xintian Hu ,T Wen ,G M Xiang ,John Shi ,Y A Han ,Xiaolei Guo ,L Q Yin ,Xiaohong Cui ,Hongkui Lv ,H Y Jia ,J G Guo ,Houdun Zeng ,G Gong ,Ke Tang ,Chengyong Gao ,X T Huang ,Y Xin ,Na Yin ,L S Geng ,G G Xin ,Xiao-Na Sun ,X D Sheng ,K Zhu ,Dezhi Huang ,Jun Yan ,Bo Gao ,Qi Gao ,J J Wei ,Y H Yu ,Y J Bi ,Tingxuan Zeng ,H L Dai ,Q Huang ,San Wu ,Rong Xu ,Ning Cheng ,M H Gu ,F R Zhu ,Fan Zhou ,B Y Pang ,J N Zhou ,Y Q Qi ,Lingling Ma ,Rui Lü ,Z Cao ,Q B Gou ,S H Feng ,B Z Dai ,C G Zhu ,Yongzhong Xing ,Zhang‐Hua Sun ,Mingjie Yang ,Z G Dai ,Z C Huang ,Bing Zhao ,Houping Wu ,Y H Yao ,Y Q Guo ,Jiajun Qin ,C F Feng ,Jian-Huan Yang ,Yi‐Zhong Fan ,Jing Zhao ,Xinyu He ,Rong Zhou ,Yudong Cui ,Wei Gao ,S C Hu ,P H T Tam ,Yiwei Bao ,Lixin Bai ,Bing-Qiang Qiao ,Z G Yao ,Chaowen Yang ,Ping Zhou ,Yan Su ,Yaodong Cheng ,X X Zhou ,Liang Gao ,Gang Xiao ,H C Song ,H B Xiao ,Cong Liu ,X X Zhai ,Da-Ming Wei ,J F Chang ,Yun-Feng Liang ,Ketao Li ,L Yang ,Shao-Qiang Xi ,H H He ,Rui Yang ,X H You ,X L Ji ,Xianchao Huang ,J T Cai ,Huibin Zhu ,Wei Tian ,W J Long ,Z Y Pei ,Qiang Yuan ,X Dong ,Bin Zhou ,S L He ,Z K Zeng ,O Shchegolev ,H.n He ,S P Zhao ,Q N Sun ,S W Cui ,Wenhao Huang ,S B Yang ,J H Fan ,Xin Zuo

doi:10.1016/j.nima.2021.165824

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%.

Full Text