Научная группа: GERDA Collaboration
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Characterization of 30 Ge-76 enriched Broad Energy Ge detectors for GERDA Phase II
(2019) Agostini, M.; Bakalyarov, A. M.; Andreotti, E.; Balata, M.; Belogurov, S.; Белогуров, Сергей Геннадьевич
The GERmanium Detector Array (Gerda) is a low background experiment located at the Laboratori Nazionali del Gran Sasso in Italy, which searches for neutrinoless double-beta decay of 76Se+2e-. Gerda has been conceived in two phases. Phase II, which started in December 2015, features several novelties including 30 new Ge-76 enriched detectors. These were manufactured according to the Broad Energy Germanium (BEGe) detector design that has a better background discrimination capability and energy resolution compared to formerly widely-used types. Prior to their installation, the new BEGe detectors were mounted in vacuum cryostats and characterized in detail in the Hades underground laboratory in Belgium. This paper describes the properties and the overall performance of these detectors during operation in vacuum. The characterization campaign provided not only direct input for Gerda Phase II data collection and analyses, but also allowed to study detector phenomena, detector correlations as well as to test the accuracy of pulse shape simulation codes.
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Modeling of GERDA Phase II data
(2020) Agostini, M.; Bakalyarov, A. M.; Balata, M.; Barabanov, I.; Belogurov, S.; Белогуров, Сергей Геннадьевич
© 2020, The Author(s).The GERmanium Detector Array (Gerda) experiment at the Gran Sasso underground laboratory (LNGS) of INFN is searching for neutrinoless double-beta (0νββ) decay of 76Ge. The technological challenge of Gerda is to operate in a “background-free” regime in the region of interest (ROI) after analysis cuts for the full 100 kg·yr target exposure of the experiment. A careful modeling and decomposition of the full-range energy spectrum is essential to predict the shape and composition of events in the ROI around Qββ for the 0νββ search, to extract a precise measurement of the half-life of the double-beta decay mode with neutrinos (2νββ) and in order to identify the location of residual impurities. The latter will permit future experiments to build strategies in order to further lower the background and achieve even better sensitivities. In this article the background decomposition prior to analysis cuts is presented for Gerda Phase II. The background model fit yields a flat spectrum in the ROI with a background index (BI) of 16.04−0.85+0.78·10−3 cts/(keV·kg·yr) for the enriched BEGe data set and 14.68−0.52+0.47·10−3 cts/(keV·kg·yr) for the enriched coaxial data set. These values are similar to the one of Phase I despite a much larger number of detectors and hence radioactive hardware components. [Figure not available: see fulltext.]
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First Search for Bosonic Superweakly Interacting Massive Particles with Masses up to 1 MeV/c(2) with GERDA
(2020) Agostini, M.; Bakalyarov, A. M.; Balata, M.; Barabanov, I.; Belogurov, S.; Белогуров, Сергей Геннадьевич
We present the first search for bosonic superweakly interacting massive particles (super-WIMPs) as keV-scale dark matter candidates performed with the GERDA experiment. GERDA is a neutrinoless double-beta decay experiment which operates high-purity germanium detectors enriched in Ge-76 in an ultralow background environment at the Laboratori Nazionali del Gran Sasso (LNGS) of INFN in Italy. Searches were performed for pseudoscalar and vector particles in the mass region from 60 keV/c(2) to 1 MeV/c(2). No evidence for a dark matter signal was observed, and the most stringent constraints on the couplings of super-WIMPS with masses above 120 keV/c(2) have been set. As an example, at a mass of 150 keV/c(2) the most stringent direct limits on the dimensionless couplings of axionlike particles and dark photons to electrons of g(ae) < 3 x 10 -12 and alpha'/alpha < 6.5 x 10(-24) at 90% credible interval, respectively, were obtained.
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Final Results of GERDA on the Search for Neutrinoless Double-beta Decay
(2020) Agostini, M.; Araujo, G. R.; Bakalyarov, A. M.; Balata, M.; Belogurov, S.; Белогуров, Сергей Геннадьевич
The GERmanium Detector Array (GERDA) experiment searched for the lepton-number-violating neutrinoless double-beta (0 nu beta beta) decay of Ge-76, whose discovery would have far-reaching implications in cosmology and particle physics. By operating bare germanium diodes, enriched in Ge-76, in an active liquid argon shield, GERDA achieved an unprecedently low background index of 5.2 x 10(-4) counts/(keV kg yr) in the signal region and met the design goal to collect an exposure of 100 kg yr in a background-free regime. When combined with the result of Phase I, no signal is observed after 127.2 kg yr of total exposure. A limit on the half-life of 0 nu beta beta decay in Ge-76 is set at T-1/2 > 1.8 x 10(26) yr at 90% C.L., which coincides with the sensitivity assuming no signal.
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An improved limit on the neutrinoless double-electron capture of 36 Ar with GERDA
(2024) Agostini, M.; Alexander, A.; Araujo, G. R.; Bakalyarov, A. M.; Belogurov, S.; Kornoukhov, V. N.; Белогуров, Сергей Геннадьевич; Корноухов, Василий Николаевич
Организационные подразделения
Организационная единица
Институт ядерной физики и технологий
Цель ИЯФиТ и стратегия развития - создание и развитие научно-образовательного центра мирового уровня в области ядерной физики и технологий, радиационного материаловедения, физики элементарных частиц, астрофизики и космофизики.
Описание
Детекторная установка GERmanium для поиска безнейтринного двойного бета-распада Ge-76 в Национальной лаборатории Гран-Сассо (LNGS)