Searching for neutrinoless double beta decay with GERDA
Searching for neutrinoless double beta decay with GERDA
复制标题
用 GERDA 寻找无中微子双 β 衰变
DOI：
10.1088/1742-6596/1342/1/012005
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发表时间：
2017
期刊：
影响因子：
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通讯作者：
Gang Yang
中科院分区：
文献类型：
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作者：
Guojian Wang;H. Mei;D. Mei;Y. Guan;Gang Yang
位于意大利格兰萨索实验室（INFN Gran Sasso Laboratory）的锗探测器阵列（Gerda）实验正在使用由同位素富集材料制成的高纯度锗探测器寻找76Ge的中微子双β衰变。新颖的实验设计、精心选择的放射性纯度材料和主动/被动屏蔽技术相结合，在衰变的q值处产生了非常低的残余背景，约为10−3 cts/(kv -kg-yr)。这使得GERDA成为第一个在100公斤/年的完全设计暴露中没有背景的实验。在46.7 kg-yr的总曝光下进行了对中微子双β衰变的搜索：23.2 kg-yr来自实验的第二阶段（第二阶段），其中背景相对于前一阶段减少了大约十倍。本文的分析包括12.4 kg- year新的二期数据。没有发现可能存在信号的证据：在90% CL下，76Ge的半衰期下限为8.0•1025年。实验中位灵敏度为5.8•1025年。实验目前正在采集数据。由于它在无背景环境下运行，其灵敏度随暴露量线性增长，预计在2018年将超过1026年。
The GERmanium Detector Array (Gerda) experiment located at the INFN Gran Sasso Laboratory (Italy), is looking for the neutrinoless double beta decay of 76Ge, by using high-purity germanium detectors made from isotopically enriched material. The combination of the novel experimental design, the careful material selection for radio-purity and the active/passive shielding techniques result in a very low residual background at the Q-value of the decay, about 10−3 cts/(keV-kg-yr). This makes GERDA the first experiment in the field to be background-free for the complete design exposure of 100 kg-yr. A search for neutrinoless double beta decay was performed with a total exposure of 46.7 kg-yr: 23.2 kg-yr come from the second phase (Phase II) of the experiment, in which the background is reduced by about a factor of ten with respect to the previous phase. The analysis presented in this paper includes 12.4 kg-yr of new Phase II data. No evidence for a possible signal is found: the lower limit for the half-life of 76Ge is 8.0 • 1025 yr at 90% CL. The experimental median sensitivity is 5.8 • 1025 yr. The experiment is currently taking data. As it is running in a background-free regime, its sensitivity grows linearly with exposure and it is expected to surpass 1026 yr within 2018.