The GERDA (GERmanium Detector Array) is an experiment for the search of neutrinoless double beta decay (0v beta) in Ge-76, 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 Ge-76 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(0v) = O(10(26)) 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 Ra-226 and Th-232 contamination levels consistent with screening results. In the first Phase II data release we found no hint for a Ov beta beta decay signal and place a limit of this process T-1/2(0v) > 5.3.10(25) yr (90% C.L., sensitivity 4.0.10(25) yr). First results of GERDA Phase II will be presented.
First results of GERDA Phase II and consistency with background models
Bettini, A.;Brugnera, R.;Garfagnini, A.;Sada, C.;Von Sturm, K.;
2017
Abstract
The GERDA (GERmanium Detector Array) is an experiment for the search of neutrinoless double beta decay (0v beta) in Ge-76, 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 Ge-76 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(0v) = O(10(26)) 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 Ra-226 and Th-232 contamination levels consistent with screening results. In the first Phase II data release we found no hint for a Ov beta beta decay signal and place a limit of this process T-1/2(0v) > 5.3.10(25) yr (90% C.L., sensitivity 4.0.10(25) yr). First results of GERDA Phase II will be presented.Pubblicazioni consigliate
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