Study Of Low Energy Photon Detection Efficiency At BESIII And Offline Data Quality Assurance

This article consists of two parts, the first section is about the research of lowenergy photon detection efficiency of EMC at BESIII, the second section is aboutoffline data quality assurance.Photon detection efficiency is one of important index for EMC, at high energyregion, the value is near to100%, but for now, we don’t get uniform results in the lowenergy region, a good knowledge of photon detection efficiency is necessary tophysical analysis. In this study, we choose the ψ(2S)â†'γ χcJdecay channel as signalsample, the photon energy of this sample is lower than300MeV. Firstly, we studybackground by Monte Carlo data which channel include ψ(2S)â†'anything decay.Secondly, we study the method of searching missing photon, define the photon window.Finally, we calculate the efficiency and study systematic errors.In the process of DQA, we preliminary check the data quality for several energypoints by Bhabha and Dimu events, and find some phenomenon, such as the deadchannel for TOF.