F. AharonianQ. AnAxikeguL. X. BaiY. X. BaiY. W. BaoD. BastieriX. J. BiY. J. BiH. CaiJ. T. CaiZ. CaoJ. ChangJ. F. ChangX. C. ChangB. M. ChenJ. ChenL. ChenM. J. ChenM. L. ChenQ. H. ChenS. H. ChenS. Z. ChenT. L. ChenX. L. ChenY. ChenN. ChengY. D. ChengS. W. CuiX. H. CuiY. D. CuiB. Z. DaiH. L. DaiZ. G. DaiDanzengluobuD. della VolpeB. D'Ettorre PiazzoliX. J. DongJ. H. FanY. Z. FanZ. X. FanJ. FangK. FangC. F. FengL. FengS. H. FengY. L. FengB. GaoC. D. GaoQ. GaoW. GaoM. M. GeL. S. GengG. H. GongQ. B. GouM. H. GuJ. G. GuoX. L. GuoY. Q. GuoY. Y. GuoY. A. HanH. H. HeH. N. HeJ. C. HeS. L. HeX. B. HeY. HeM. HellerY. K. HorC. HouX. HouH. B. HuS. HuS. C. HuX. J. HuD. H. HuangQ. L. HuangW. H. HuangX. T. HuangZ. C. HuangF. JiX. L. JiH. Y. JiaK. JiaK. JiangZ. J. JiangC. JinD. KuleshovK. LevochkinB. LiB. B. LiC. LiF. LiH. LiH. B. LiH. C. LiH. Y. LiJ. LiK. LiW. L. LiState Key Laboratory of Particle Detection & ElectronicsNanjing UniversityShanghai Astronomical Observatory Chinese Academy of SciencesInstitute for Nuclear Research of the Russian Academy of SciencesShandong UniversityWuhan UniversityYunnan UniversityInstitute of High Energy Physics Chinese Academy of ScienceUniversity of Chinese Academy of SciencesYantai UniversityGuangzhou UniversityTsinghua UniversitySun Yat-Sen UniversityUniversity of Science and Technology of ChinaZhengzhou UniversityDublin Institute for Advanced StudiesUniversità degli Studi di Napoli Federico IISichuan UniversityNational Astronomical Observatories Chinese Academy of SciencesMax-Planck-Institut für KernphysikSouthwest Jiaotong UniversityPurple Mountain Observatory Chinese Academy of SciencesUniversité de GenèveHebei Normal UniversityTibet UniversityTIANFU Cosmic Ray Research Center2022-08-042022-08-042021-06-11Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. Vol.1001, (2021)016890022-s2.0-85104658625https://repository.li.mahidol.ac.th/handle/20.500.14594/78997The Large High Altitude Air Shower Observatory (LHAASO) is a new generation hybrid cosmic ray observatory which is expected to reveal the mystery of the origin of cosmic rays. The one square kilometer array (KM2A) consisting of 5195 Electromagnetic particle Detectors (ED) and 1188 Muon Detectors (MD) is a sub-array of LHAASO. The EDs are designed to measure the density and arriving time of the secondary particles of extensive air showers. The performance of the EDs is tested for the quality control after construction in the laboratory at sea level. In this paper, the performance of more than four thousands EDs is summarized. The performance of all tested EDs meets the design requirements with the time resolution of 1.6 ns, the detection efficiency of 97.8%, charge resolution for single particle of 18.5% and count rate around 480 Hz. Furthermore, one ED is singled out for monitoring of the long-term stability over a period of nearly two years from December 2018 to November 2020.Mahidol UniversityPhysics and AstronomyArticleSCOPUS10.1016/j.nima.2021.165193