BESIII漂移室低横动量重建方法的研究

Main Drift Chamber (MDC) is used to measure the properties of charged particles by making precise measurements of position, momentum and ionization energy loss and proviede trigger information. Track reconsturcton is designed to find the charged particle's track and to reconstruct its momentum and position.BESIII final states have a large proportion of low transverse momentum tracks. Quality improvement for low transverse momentum tracks will be a great benefit to physical results and small signal searching. High background, high noise and track circled in MDC are special problems for BESIII MDC reconstruction. So tuning on tracking parameters will be done to improve the robustness for noise in tracking. Several new tracking methods will be developed to enhance the low transverse momentum track quality.

漂移室（MDC）是用于测量带电粒子径迹的动量、电离能损并提供触发信号的大型气体探测器。漂移室重建的任务是精确还原带电粒子的动量和位置信息。BESIII末态中低横动量径迹占很大比例，改进低横动量径迹的重建效率和精度对提高BESIII物理结果的质量和开展稀有事例的研究具有非常重大的意义。BESIII漂移室低横动量径迹的重建面临着高本底高噪声的工作环境和径迹打圈等特殊问题。因此我们将通过寻迹参数的优化增加抗噪声的能力，并结合BESIII漂移室的特点采取不同的研究方案，开发出新的算法以提高低横动量径迹重建的质量。

BESIII实验中漂移室（MDC）重建的主要任务是进行带电粒子径迹动量和位置的精确还原。在本实验的末态中，低横动量径迹占很大比例。本项目根据低横动量径迹的特点，优化了各个寻迹过程及其参数；研究了一种模式字典的扩充新方法并进行了基于Hough变换的寻迹方法的初步研究；此外研究了在重建时排除噪声的方法。已有算法的改进和优化以及新算法引入提高了低横动量径迹的重建效率，并显著提升了末态多径迹事例的信号挑选效率和径迹质量，这为BESIII开展稀有事例的研究提供了有利条件。