Physik Department and Excellence Cluster Universe, Technische Universität München, Germany.
Phys Rev Lett. 2013 Sep 20;111(12):122503. doi: 10.1103/PhysRevLett.111.122503. Epub 2013 Sep 19.
Neutrinoless double beta decay is a process that violates lepton number conservation. It is predicted to occur in extensions of the standard model of particle physics. This Letter reports the results from phase I of the Germanium Detector Array (GERDA) experiment at the Gran Sasso Laboratory (Italy) searching for neutrinoless double beta decay of the isotope (76)Ge. Data considered in the present analysis have been collected between November 2011 and May 2013 with a total exposure of 21.6 kg yr. A blind analysis is performed. The background index is about 1 × 10(-2) counts/(keV kg yr) after pulse shape discrimination. No signal is observed and a lower limit is derived for the half-life of neutrinoless double beta decay of (76)Ge, T(1/2)(0ν) >2.1 × 10(25) yr (90% C.L.). The combination with the results from the previous experiments with (76)Ge yields T(1/2)(0ν)>3.0 × 10(25) yr (90% C.L.).
无中微子双β衰变是一种违反轻子数守恒的过程。它被预测发生在粒子物理标准模型的扩展中。这封信报告了德国探测器阵列（GERDA）实验在意大利格兰萨索实验室进行的第一阶段的结果，该实验旨在寻找同位素（76）Ge 的无中微子双β衰变。本分析中考虑的数据是在 2011 年 11 月至 2013 年 5 月之间收集的，总暴露量为 21.6 kg yr。进行了盲分析。在经过脉冲形状甄别后，背景指数约为 1×10(-2) 计数/（keV kg yr）。未观察到信号，并为（76）Ge 的无中微子双β衰变半衰期得出下限，T(1/2)(0ν)>2.1×10(25) yr（90%置信区间）。与之前使用（76）Ge 的实验结果相结合，得出 T(1/2)(0ν)>3.0×10(25) yr（90%置信区间）。
