Online monitoring of the center-of-mass energy from real data at BESⅢ  

作　　者：Jiada Lu Yanjia Xiao Xiaobin Ji 

机构地区：[1]Institute of High Energy Physics,Chinese Academy of Sciences,Beijing 100049,China [2]University of Chinese Academy of Sciences,Beijing 100049,China

出　　处：《Radiation Detection Technology and Methods》2020年第3期337-344,共8页辐射探测技术与方法（英文）

基　　金：provided by National Natural Science Foundation of China(NSFC)under Contracts Nos.11775245,11275210,U1832204

摘　　要：Background Data Quality Monitoring system(DQM)was developed to monitor data quality at BESⅢexperiment in real time.The stable center-of-mass energy(E_(cms))is essential for the data taking.Online monitoring the E_(cms)can help find the beam energy shift in time.Purpose The purpose is to monitor the E_(cms)in DQM system in real time.Methods The E_(cms)is measured using Bhabha scattering process in DQM system,due to its large cross section and low background level.The E_(cms)is calculated from the invariant mass of e^(+)e^(-),and the correction value from radiation effect and momentum calibration.Result The E_(cms)calculated with DQM system shows a good consistency with that from offline reconstruction within error.The results are validated with data taken in 2013.The overall systematic uncertainty includes 0.39 MeV/c^(2) from signal extraction and 2.54 MeV/c^(2) from calibration and radiation correction.Conclusions The E_(cms)calculated from Bhabha scattering process is now available on DQM system in real time,which can be used as references for researchers to operate BESⅢexperiment.

关 键 词：DQM Center-of-mass energy Bhabha process 

分 类 号：O57[理学—粒子物理与原子核物理]