Calibration study of the X-T relation for the BESIII drift chamberSupported by National Natural Science Foundation of China (11205184, 11205182, 11121092, 11179020) and Joint Funds of National Natural Science Foundation of China (U1232201)

• Published in: Chinese physics C Vol. 39; no. 2
• Main Authors: Kang, Xiao-Lin, Wu, Ling-Hui, Wu, Zhi, Luo, Tao, Hu, Chen, Wang, Hai-Xia, Fang, Shuang-Shi, He, Kang-Lin, Li, Wei-Dong, Li, Wei-Guo, Liu, Huai-Min, Mao, Ze-Pu, Wang, Liang-Liang, Yuan, Ye, Zhang, Yao
• Format: Journal Article
• Language: English
• Published: Chinese Physical Society and the Institute of High Energy Physics of the Chinese Academy of Sciences and the Institute of Modern Physics of the Chinese Academy of Sciences and IOP Publishing 01.02.2015
• Subjects: BESIII; calibration; drift chamber; relation
• ISSN: 1674-1137
• DOI: 10.1088/1674-1137/39/2/026002

Offline calibration plays an important role in BESIII offline data processing. In order to achieve good spatial and momentum resolution, it is necessary to implement high precision offline calibration for the BESIII drift chamber. This paper studies the time-to-distance relations, which are important calibration constants for track reconstruction. The parameterization of the time-to-distance relation, studies of left-right asymmetry and studies of variation with entrance angle are performed. The impact of dead channels on the time-to-distance relation is given special attention in order to reduce the shift in measured momentum for tracks passing near dead cells. Finally we present the resolutions for barrel Bhabha events (|cosθ|<0.8) from a J/ψ data set taken in 2012. The average spatial resolution is 123 μm and the momentum resolution for 1.548 GeV/c Bhabha tracks is 11.9 MeV/c.