【作者】 蒋林立；

【导师】 张子平； 王贻芳；

【作者基本信息】 中国科学技术大学 ， 粒子物理与原子核物理， 2006， 博士

【摘要】 北京正负电子对撞机重大改造工程(BEPCⅡ)正在进行，改造后的北京正负电子对撞机亮度将提高100倍，其探测器(BESⅢ)性能也有很大提高。飞行时间计数器是BESⅢ一个子探测器，它的功能是测量带电粒子的飞行时间，进行粒子鉴别。本论文的主要内容是关于BESⅢ飞行时间计数器的束流实验及其蒙特卡罗模拟研究，以及BESⅢ飞行时间计数器离线重建软件和刻度软件的开发和研究。 BESⅢ飞行时间计数器模型的束流实验是在北京正负电子对撞机试验束提供的800Mev电子束流上进行的。实验研究了TOF的主要性能，结果证明了BESⅢ飞行时间计数器所选的各种材料和条件的性能可以达到预期指标。闪烁体在厚度为5cm时具有较好的时间分辨。不同反射率包装材料的实验结果是：反射率低的铝膜包装的时间分辨要比反射率高的ESR包装的时间分辨好。利用Geant4，我们进行了BESⅢ飞行时间计数器模型束流实验的蒙特卡罗模拟研究。不同厚度闪烁体以及不同反射率包装材料下的模拟结果和实验结果一致。利用蒙特卡罗模拟结果，主要从不同情况下的光电倍增管脉冲的幅度以及上升时间的比较，对束流实验结果进行了解释。 在BESⅢ离线数据处理框架下，利用面向对象的C++程序设计语言，开发了BESⅢ飞行时间计数器离线处理重建系统和离线刻度系统。结合主漂移室的重建软件以及径迹外推软件，利用蒙特卡罗数据，对BESⅢ飞行时间计数器离线重建软件进行了测试，给出了一些初步的测试结果。TOF重建软件能够很好地工作，重建结果已经被物理分析软件使用。TOF刻度软件的初步版本已经完成，对分辨率，刻度方法进行了研究。利用蒙特卡罗产生的巴巴事例，对TOF离线刻度软件进行了测试，并将这些刻度常数用到TOF重建软件中，经过物理分析，证明TOF事例重建系统和刻度系统对于理想的蒙特卡罗数据工作基本正常。 在BESⅢ离线数据处理软件(BOSS)发布BOSS5.0.0版本后，利用蒙特卡罗数据对一些初步的物理结果进行了检查。主要包括强子的重建效率、粒子鉴别效率的检查，D~0-(?)~0混合和CP破缺的寻找这几个方面。通过这些检查检验了BESⅢ离线数据处理软件的性能。更多还原

【Abstract】 The upgrade project of the Beijing Electron Positron Collider known as BEPC II is carried through now. The luminosity of BEPCII will be increased by two orders, and the performance of its detector BESIII, upgraded version of Beijing Electron Spectrometer (BES), will be improved significantly. Time of Flight (TOF) counters as one of its sub-detector is mainly used to measure the time of flight of charged particles for particle identification. This thesis is focused on the beam test of BESIII TOF detector and the Monte Carlo simulation, as well as the design of TOF offline reconstruction and calibration software.BESIII TOF prototype beam test is done with an 800MeV electron beam provided by the BEPC-Linac. The performance of BESIII TOF is well studied. The results indicate that the BESIII TOF can reach its expected design goal. The test results for scintillators of different thickness show that the one of 5cm thickness has the best time resolution. When the scintillator is wrapped with different reflectivity material, the time resolution using aluminum film is better than ESR film, although the reflectivity of ESR film is higher than that of aluminum film. Based on Geant4 the Monte Carlo simulation study on BESIII TOF prototype beam test is done. The simulation results are consistent with what obtained from beam test, and therefore make us further understand that the results from beam test could be well explained by the outputted PMT pulse amplitude and its raise time in different cases.Under the framework of BESIII offline data analysis, The BESIII TOF offline reconstruction and calibration system has been developed based on Objected-Oriented C++ language. The BESIII TOF reconstruction system has been tuned and tested using Monte Carlo data, associated with the main draft chamber reconstruction system and track extrapolation system. Some test results are given. It shows that the BESIII TOF reconstruction system works quite well, the reconstructed results have been used in physics analysis software. The BESIII calibration system has also been tested using Monte Carlo Bhabha events. The calibration constants obtained have been used into the TOF reconstruction system.Based on BOSS5.0.0,preliminary checks have been done for some physics subjects using M.C data,such as the efficiency of hadron reconstruction and PID.and its application更多还原