/ Experiment-Nucl

First results of GERDA Phase II and consistency with background models

Published in: J.Phys.Conf.Ser.
Year: 2017
Vol.: 798    Num./Issue: 1
Page No: 012106
Pages: 6
Year: 2017-03-15 published

Abstract: The GERDA (GERmanium Detector Array) is an experiment for the search of neutrinoless double beta decay (0νββ) in (76)Ge, located at Laboratori Nazionali del Gran Sasso of INFN (Italy). GERDA operates bare high purity germanium detectors submersed in liquid Argon (LAr). Phase II of data-taking started in Dec 2015 and is currently ongoing. In Phase II 35 kg of germanium detectors enriched in (76)Ge including thirty newly produced Broad Energy Germanium (BEGe) detectors is operating to reach an exposure of 100 kg·yr within about 3 years data taking. The design goal of Phase II is to reduce the background by one order of magnitude to get the sensitivity for $T_{1/2}^{0\nu } = O\left( {{{10}^{26}}} \right){\rm{ yr}}$. To achieve the necessary background reduction, the setup was complemented with LAr veto. Analysis of the background spectrum of Phase II demonstrates consistency with the background models. Furthermore (226)Ra and (232)Th contamination levels consistent with screening results. In the first Phase II data release we found no hint for a 0νββ decay signal and place a limit of this process $T_{1/2}^{0\nu } > 5.3 \cdot {10^{25}}$ yr (90% C.L., sensitivity 4.0·10(25) yr). First results of GERDA Phase II will be presented.

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DOI: 10.1088/1742-6596/798/1/012106