Track segment finding with CGEM-IT and matching to outer drift chamber tracks in the BESIII detector**Supported by National Key Basic Research Program of China (2015CB856706), National Natural Science Foundation of China (11575222, 11205184, 11205182, 11121092, 11475185) and Joint Funds of National Natural Science Foundation of China (U1232201)

Abstract

The relative differences in coordinates of Cylindrical Gas Electron Multiplier Detector-based Inner Tracker (CGEM-IT) clusters are studied to search for track segments in CGEM-IT for the BESIII experiment. With the full simulation of single muon track samples, clear patterns are found and parameterized for the correct cluster combinations. The cluster combinations satisfying the patterns are selected as track segment candidates in CGEM-IT with an efficiency higher than 99%. The parameters of the track segments are obtained by a helix fitting. Some χ2 quantities, evaluating the differences in track parameters between the track segments in CGEM-IT and the tracks found in the outer drift chamber, are calculated and used to match them. Proper χ2 requirements are determined as a function of transverse momentum and the matching efficiency is found to be reasonable.