标题： 位置重建和PandaX-4T探测器的表面本底模型 显示英文标题

标题： Position reconstruction and surface background model for the PandaX-4T detector

摘要： 我们报告了PandaX-4T暗物质直接搜索实验的位置重建方法和表面本底模型。 这项工作开发了两种位置重建算法：模板匹配（TM）方法和光子接受函数（PAF）方法。 这两种方法均基于光传感器收集的次级闪烁光模式来确定事件的水平位置。 在对分辨率、均匀性和鲁棒性进行全面评估后，选择了PAF方法进行位置重建，而TM方法用于验证。 PAF方法对于具有底部电荷1500 PE（约14 keV）的典型$S2$信号，实现了体事件分辨率为1.0 mm，表面事件分辨率为4.4 mm。 均匀性约为20%。 鲁棒性研究显示，由于某些光电倍增管的停用，调试运行（Run0）和第一个科学运行（Run1）的平均偏差分别为5.1 mm和8.8 mm。 基于PAF方法开发了一个数据驱动的表面本底模型。 表面本底估计为Run0（0.54吨$\cdot$年）的$0.09 \pm 0.06$事件和Run1（1.00吨$\cdot$年）的$0.17 \pm 0.11$事件。 显示英文摘要

摘要： We report the position reconstruction methods and surface background model for the PandaX-4T dark matter direct search experiment. This work develops two position reconstruction algorithms: template matching (TM) method and photon acceptance function (PAF) method. Both methods determine the horizontal position of events based on the light pattern of secondary scintillation collected by the light sensors. After a comprehensive evaluation of resolution, uniformity, and robustness, the PAF method was selected for position reconstruction, while the TM method was employed for verification. The PAF method achieves a bulk event resolution of 1.0 mm and a surface event resolution of 4.4 mm for a typical $S2$ signal with a bottom charge of 1500 PE (about 14 keV). The uniformity is around 20\%. Robustness studies reveal average deviations of 5.1 mm and 8.8 mm for the commissioning run (Run0) and the first science run (Run1), respectively, due to the deactivation of certain PMTs. A data-driven surface background model is developed based on the PAF method. The surface background is estimated to be $0.09 \pm 0.06$ events for Run0 (0.54 tonne$\cdot$year) and $0.17 \pm 0.11$ events for Run1 (1.00 tonne$\cdot$year).