标题： 近阈值能量下采用形状匹配脉冲形状方法的点接触锗探测器的体表事件鉴别 显示英文标题

标题： Bulk-Surface Event Discrimination in Point Contact Germanium Detectors at Near-Threshold Energies with Shape-Matching Pulse-Shape Methods

摘要： 点接触型锗（pPCGe）探测器已被广泛用于低能物理事件（如中微子和暗物质）的搜索。 这是由于其具备增强的本底抑制能力、在亚千电子伏特范围内的灵敏度以及特别优异的能量分辨率。 然而，对于靠近钝化表面的事件，pPCGe 受到由表面效应引起的非正常行为的影响。 一般来说，这些表面事件可以通过其较慢的脉冲上升时间与发生在锗晶体本体中的事件区分开来。 不幸的是，在亚千电子伏特能量范围内，本体事件和表面事件的上升时间谱开始相互卷积。 在这项工作中，我们提出了一种基于互相关形状匹配结合低通滤波器的新方法，以约束信号脉冲的初始参数估计。 这一最低层面上的改进使计算时间减少了50%，上升时间分辨率得到了提升，最终将提高整体分析性能。 为了评估该方法的性能，我们使用可编程脉冲发生模块（脉冲器）模拟了类似于本体和表面脉冲的人工脉冲。 然后使用脉冲器生成的脉冲来研究近阈值能量下的脉冲行为，表明本体光谱中的本底泄漏减少约70%。 最后，该方法在TEXONO实验收集的数据上进行了测试，结果与脉冲器观察结果一致，并证明了至少可以将分析阈值降低10电子伏特的可能性。 显示英文摘要

摘要： The p-type point-contact germanium (pPCGe) detectors have been widely adopted in searches for low energy physics events such as neutrinos and dark matter. This is due to their enhanced capabilities of background rejection, sensitivity at energies as low as the sub-keV range and particularly fine energy resolution. Nonetheless, the pPCGe is subject to irregular behaviour caused by surface effects for events near the passivated surface. These surface events can, in general, be distinguished from events that occur in the germanium crystal bulk by its slower pulse rise time. Unfortunately, the rise-time spectra of bulk and surface events starts to convolve with each other at sub-keV energies. In this work, we propose a novel method based on cross-correlation shape-matching combined with a low-pass filter to constrain the initial parameter estimates of the signal pulse. This improvement at the lowest level leads to a 50% reduction in computation time and refinements in the rise-time resolution, which will, in the end, enhance the overall analysis. To evaluate the performance of the method, we simulate artificial pulses that resembles bulk and surface pulses by using a programmable pulse generator module (pulser). The pulser-generated pulses are then used to examine the pulse behaviours at near-threshold energies, suggesting a roughly 70% background-leakage reduction in the bulk spectrum. Finally, the method is tested on data collected from the TEXONO experiment, where the results are consistent with our observations in pulser and demonstrated the possibility of lowering the analysis threshold by at least 10eV.