Pulse shape discrimination studies with a Broad-Energy Germanium detector for signal identification and background suppression in the GERDA double beta decay experiment
Pulse shape discrimination studies with a Broad-Energy Germanium detector for signal identification and background suppression in the GERDA double beta decay experiment
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DOI：
10.1088/1748-0221/4/10/p10007
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发表时间：
2009-10-01
影响因子：
1.3
通讯作者：
Schoenert, Stefan
中科院分区：
文献类型：
--
作者：
Budjas, Dusan;Heider, Marik Barnabe;Schoenert, Stefan
首次研究了宽能锗（BEGe）探测器的事件鉴别。一种新的脉冲形状的方法，利用BEGe探测器内的特征电场分布，允许有效地识别单站点事件和拒绝多站点事件。第一个是典型的无中微子双β衰变（0纽β β）和后者的背景从伽马射线相互作用。在接近Q（beta beta）（Ge-76）= 2039 keV的能量下，所获得的本底存活概率对于来自Co-60的事件为（0.93 +/- 0.08）%，对于来自Ra-226的事件为（21 +/- 3）%，并且对于来自Th-228的事件为（40 +/- 2）%。这种背景抑制是通过Th-228双逃逸事件的（89 +/-1）%接受度实现的，所述双逃逸事件由单位点相互作用主导。对于0 nu β β衰变事件，预期接受度大致相等。准直光束和康普顿符合测量表明，歧视是在很大程度上独立于晶体内的相互作用的位置，并验证脉冲形状切割的能量范围内的Q（β β）。目前正在研究贝加探测器在GERDA和马约拉纳双β衰变实验中的应用。
First studies of event discrimination with a Broad-Energy Germanium (BEGe) detector are presented. A novel pulse shape method, exploiting the characteristic electrical field distribution inside BEGe detectors, allows to identify efficiently single-site events and to reject multi-site events. The first are typical for neutrinoless double beta decays (0 nu beta beta) and the latter for backgrounds from gamma-ray interactions. The obtained survival probabilities of backgrounds at energies close to Q(beta beta)(Ge-76) = 2039 keV are (0.93 +/- 0.08)% for events from Co-60, (21 +/- 3)% from Ra-226 and (40 +/- 2)% from Th-228. This background suppression is achieved with (89 +/- 1)% acceptance of Th-228 double escape events, which are dominated by single site interactions. Approximately equal acceptance is expected for 0 nu beta beta-decay events. Collimated beam and Compton coincidence measurements demonstrate that the discrimination is largely independent of the interaction location inside the crystal and validate the pulse-shape cut in the energy range of Q(beta beta). The application of BEGe detectors in the GERDA and the Majorana double beta decay experiments is under study.