The principle of the method for the BESⅢ event start time determination and the code construction are described. The investigation of influence of the noise, the method of rejecting noise and the performance checking by the Monte Carlo physics data sample are also presented. The preliminary results got from the Monte Carlo simulation are presented, the reconstruction efficiency of J/ψ → anything events at noise level 0 - 60% can achieve above 99%, and the error rate is below 1%.
Data quality monitoring （DQM） plays an important role in data taking at the BESⅢ experiments.DQM is used to monitor detector status and data quality.A DQM framework （DQMF） has been developed to make it possible to reuse the BESⅢ offline reconstruction system in the online environment.In this framework,the DQMF can also simulate a virtual data taking environment,transfer events to the event display,publish histograms to a histogram presenter in a fixed interval,and dump histograms into a ROOT file.The DQMF has been stably running throughout BESⅢ data taking.
The results of a study of event tagging strategies for elementary physics processes in the T-charm region are presented. The algorithm for online event filtering is optimized by adopting the information provided by different sub-detectors according to their strengths and capacities. The algorithm is tested with various generated physics and background events. The results indicate that the algorithm satisfies the requirements of BESⅢ physics analysis and its DAQ system.
The calibration algorithm for RPC-based muon detector at BESIII has been developed. The calibration method, calibration error and algorithm performance are studied. The primary results of efficiency and noise at layer, module and strip levels have been calibrated with cosmic ray data. The calibration constants are available for simulation and reconstruction tuning. The results of Monte Carlo and data are also compared to check the validation and reliability of the algorithm.
The performance of histogram comparison is studied for the various types of hypothesis test methods. The Kolmogorov test is recommended for the software and data validation and the minimum event numbers for different distributions are given in order to get more reliable results. A new bin content comparison method is implemented to deal with the hitmap-like histograms.
Software alignment is quite important for a tracking detector to reach its ultimate position accuracy and momentum resolution. We developed a new alignment algorithm for the BESⅢ Main Drift Chamber using the Kalman Filter method. Two different types of data which are helix tracks and straight tracks are used to test this algorithm, and the results show that the design and implementation is successful.
Material effect of inner-detectors on the performances of the BESⅢ Electromagnetic Calorimeter （EMC） is investigated. The BESⅢ Time-Of-Flight counters （TOF） have been utilized to improve the energy resolution and detection efficiency for photons after a careful energy calibration. A matching algorithm between TOF and EMC energy deposits is developed, and the effects of beam-related background are discussed. The energy resolution is improved and the photon detection efficiency can be increased by the combined measurement of EMC and TOF detectors.
