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First results of GERDA Phase II and consistency with background models
[摘要] The GERDA (GERmanium Detector Array) is an experiment for the search of neutrinoless double beta decay (0νββ) in76Ge, 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 in76Ge 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 . 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. Furthermore226Ra and232Th 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 yr (90% C.L., sensitivity 4.0•1025yr). First results of GERDA Phase II will be presented.
[发布日期]  [发布机构] LNGS and GSSI (INFN), Italy^1;LNS (INFN), Italy^2;IoP Cracow, Poland^3;TU Dresden, Germany^4;JINR Dubna, Russia^5;EU Geel, Belgium^6;MPI Heidelberg, Germany^7;U. Bicocca Milan, Italy^8;INFN Bicocca Milan, Italy; (10) U.d.Studi Milan, Italy; (11) INR Moscow, Russia; (12) ITEP Moscow, Russia; (13) Kurchatov Moscow, Russia; (14) MPI Munich, Germany; (15) TU Munich, Germany; (16) U. Padova, Italy; (17) INFN Padova, Italy; (18) EKUT Tübingen, Germany; (19) U. Zurich, Switzerland; (20) Presenter, Switzerland^9
[效力级别] 天文学 [学科分类] 天文学(综合)
[关键词] Background model;Background spectra;Contamination levels;Data release;Germanium detector;High purity germanium detectors;Liquid argon;Neutrinoless double-beta decays [时效性] 
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