The Study And Improvement Of The Offline Calibration Of BES Muon Detector

This paper describes The Beijing Electron Position Collider(BEPC) and the Beijing Spectrometer(BES),describes the structure , capability and basis method of Muon Detector. The BES2 Muon Counter performance has been careful studied. The method and flow of offline data calibration are introduced in this report. The selection of dimuon events, the calculation of Z resolution are explained. The similarities and differences among several calibration methods are presented. This paper narrates the research and the improvement of the new calibration software in detail. The comparison of the Z resolution from several methods is summarized with the calibration results of real data and MC data. A better determination of Z coordinate and a better resolution on Z coordinate have been achieved. All these will help physics analysis that use Muon Counter information much.BEPC is the national important lab, consists of the injector, the storage ring, the transportation line, the Beijing Spectrometer (BES), the Beijing Synchrotron Radiation Facility and the computer center. BES is a general-purpose detector located in the interaction region at the southern end of the BEPC storage ring, where the electron and positron beams collide. BEPC and BES are the only tools of its kind in the world, which operate in the tau-charm energy region with high luminosity. Since their operation in 1990, a series of world-class physics results have been achieved.The Counter is the very important detector in BES, composed of 3 layers of square aluminum proportional chambers totaling 1512 with each being 4 m long and related electronics circuits. It can record the muon events that have very strong penetrating ability and determine the position of bombardment. Its precision is the important parameter of BES.