论文标题
GERDA II期的脉冲形状分析
Pulse shape analysis in GERDA Phase II
论文作者
论文摘要
锗探测器阵列(GERDA)合作搜索了中微子双$β$衰减的$^{76} $ ge,使用Infn的实验室nazionali del Gran sasso使用同位素富集的高纯族探测器。在第一阶段(2011-2013)之后,该实验受益于多次升级,包括基于LAR仪器的额外否决权和通过点接触式锗探测器的质量显着增加,从而提高了II期(2015- 2019年)的半衰期灵敏度(通过一个数量级)。在背景缓解策略的核心中,对单个脉冲的时间曲线的分析提供了对信号状和背景样事件的强大拓扑歧视。在评估脉冲形状辨别性能的评估中,考虑了常规$^{228} $ th校准和物理数据的数据。在这项工作中,我们描述了应用于GERDA II期收集的数据的各种方法,与103.7 kg $ \ cdot $ yr相对应。这些方法在Q $ _ {ββ} $ = 2039 keV附近的感兴趣区域中抑制背景约5倍,同时保留信号的(81 $ \ pm $ 3)。此外,还提供了最终数据分析中使用的详尽参数列表。
The GERmanium Detector Array (GERDA) collaboration searched for neutrinoless double-$β$ decay in $^{76}$Ge using isotopically enriched high purity germanium detectors at the Laboratori Nazionali del Gran Sasso of INFN. After Phase I (2011-2013), the experiment benefited from several upgrades, including an additional active veto based on LAr instrumentation and a significant increase of mass by point-contact germanium detectors that improved the half-life sensitivity of Phase II (2015-2019) by an order of magnitude. At the core of the background mitigation strategy, the analysis of the time profile of individual pulses provides a powerful topological discrimination of signal-like and background-like events. Data from regular $^{228}$Th calibrations and physics data were both considered in the evaluation of the pulse shape discrimination performance. In this work, we describe the various methods applied to the data collected in GERDA Phase II corresponding to an exposure of 103.7 kg$\cdot$yr. These methods suppress the background by a factor of about 5 in the region of interest around Q$_{ββ}$ = 2039 keV, while preserving (81$\pm$3)% of the signal. In addition, an exhaustive list of parameters is provided which were used in the final data analysis.