Research Of Method For Single Event Data Process In The Cosmic Ray Experiment Of BESIII Drift Chamber

The cosmic ray experiment of BESIII drift chamber is the last step of the construction of drift chamber, which gives a comprehensive test to the BESIII drift chamber and Electronics system before formal installation. Data acquisition (DAQ) system is an important part of the cosmic ray experiment system. The monitoring module of DAQ monitors the running of drift chamber in the whole process of the cosmic ray experiment. Single event display is an important monitoring way of DAQ. it monitors the running of drift chamber in the way of three-dimensional graphs. The main purpose of data process of single event in the cosmic ray experiment is providing spatial position data of cosmic ray hits in the drift chamber for single event display program to display the track of cosmic ray in the drift chamber.This dissertation first introduces something about BEPC and BESIII ,data acquisition system and the structure of drift charm. After tried two methods for data processing: Processing based on offline reconstruction and Processing based on three-dimensional geometry calculation, this dissertation designs the third method: Processing based on three-dimensional track-fitting. The result got by the first method is accurate, but time cost is too long and it is dependent on GAUDI which damages the independence of the processing. The second method can get result quickly and be independent, but the result is inaccurate. The third method also can get result quickly and be independent, the accuracy of the result can also meet the accuracy demand in single event data processing of cosmic ray.This dissertation also designs and implements the data processing of single event based on three-dimensional track-fitting, and object-oriented techniques are used to encapsulate the data, even more principle of least squares is taken advantage of to desert the noise data in two-dimensional space and for track-fitting of cosmic ray track, which improve the processing speed and the accuracy of the result. At last, this dissertation takes advantage of MC simulation data to prove the validity of this method.As an important part of cosmic ray experiment of drift chamber, this design has been applied in the cosmic ray experiment of drift chamber successfully.