The Study Of The Performance Of BESâ…¢ Drift Chamber And The Monitor Of Data Quality

The BESIII detector is commissioned at the Beijing Electron Positron Collider(BEPCII). The goals of the BESIII are the precision measurement and the search for new physics in the τ-Charm energy. BESIII includes four sub-detectors, from inside to outside, are in order main drift chamber, time of flight, CsI electro-magnetic calorimeter, muon identifier. Drift chamber is the detector which is located in the most inside. MDC measures time and charge information of the passing tracks. The time information is used to reconstruct the track and momentum of charged particles. MDC adopts small cell helium-based drift chamber. It provides high efficiency, good spatial resolution(130μm), good momentum resolution (0.5%@1GeV/c), comparative dE/dx resolution and to operate stably in the condition of high luminosity of BEPCII. It is located in1T magnetic field. The performance of BESIII drift chamber contain spatial resolution, momentum resolution, hit efficiency and reconstructed efficiency. The thesis introduces the performance of main drift chamber, and also describes the stability of data quality for psipp data from Dec.12in2010to May.3in2011using bhabha data. We found that the hit efficiency in some run reduced suddenly, caused by the trip of MDC HV. We developed a sofeware package which can throw away the events in the trip time.