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139 results on '"GERDA collaboration"'

1. Searches for new physics below twice the electron mass with GERDA

Author: GERDA Collaboration, M. Agostini, A. Alexander, G. Araujo, A. M. Bakalyarov, M. Balata, I. Barabanov, L. Baudis, C. Bauer, S. Belogurov, A. Bettini, L. Bezrukov, V. Biancacci, E. Bossio, V. Bothe, R. Brugnera, A. Caldwell, S. Calgaro, C. Cattadori, A. Chernogorov, P.-J. Chiu, T. Comellato, V. D’Andrea, E. V. Demidova, N. Di Marco, E. Doroshkevich, M. Fomina, A. Gangapshev, A. Garfagnini, C. Gooch, P. Grabmayr, V. Gurentsov, K. Gusev, J. Hakenmüller, S. Hemmer, W. Hofmann, J. Huang, M. Hult, L. V. Inzhechik, J. Janicskó Csáthy, J. Jochum, M. Junker, V. Kazalov, Y. Kermaïdic, H. Khushbakht, T. Kihm, K. Kilgus, I. V. Kirpichnikov, A. Klimenko, K. T. Knöpfle, O. Kochetov, V. N. Kornoukhov, P. Krause, V. V. Kuzminov, M. Laubenstein, M. Lindner, I. Lippi, A. Lubashevskiy, B. Lubsandorzhiev, G. Lutter, C. Macolino, B. Majorovits, W. Maneschg, G. Marshall, M. Misiaszek, M. Morella, Y. Müller, I. Nemchenok, M. Neuberger, L. Pandola, K. Pelczar, L. Pertoldi, P. Piseri, A. Pullia, C. Ransom, L. Rauscher, M. Redchuk, S. Riboldi, N. Rumyantseva, C. Sada, S. Sailer, F. Salamida, S. Schönert, J. Schreiner, A-K. Schütz, O. Schulz, M. Schwarz, B. Schwingenheuer, O. Selivanenko, E. Shevchik, M. Shirchenko, L. Shtembari, H. Simgen, A. Smolnikov, D. Stukov, S. Sullivan, A. A. Vasenko, A. Veresnikova, C. Vignoli, K. von Sturm, T. Wester, C. Wiesinger, M. Wojcik, E. Yanovich, B. Zatschler, I. Zhitnikov, S. V. Zhukov, D. Zinatulina, A. Zschocke, K. Zuber, and G. Zuzel
Subjects: Astrophysics, QB460-466, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract: Abstract A search for full energy depositions from bosonic keV-scale dark matter candidates of masses between 65 and 1021 keV has been performed with data collected during Phase II of the GERmanium Detector Array (Gerda) experiment. Our analysis includes direct dark matter absorption as well as dark Compton scattering. With a total exposure of 105.5 kg years, no evidence for a signal above the background has been observed. The resulting exclusion limits deduced with either Bayesian or Frequentist statistics are the most stringent direct constraints in the major part of the 140–1021 keV mass range. As an example, at a mass of 150 keV the dimensionless coupling of dark photons and axion-like particles to electrons has been constrained to $$\alpha '/\alpha 1.5 \times 10^{24}$$ τ n > 1.5 × 10 24 years and for a proton $$\tau _\textrm{p} > 1.3 \times 10^{24}$$ τ p > 1.3 × 10 24 years at 90% CI. For the electron decay $$e^\text {-} \rightarrow \nu _\textrm{e} \gamma $$ e - → ν e γ a lower limit of $$\tau _\textrm{e} > 5.4\times 10^{25}$$ τ e > 5.4 × 10 25 years at 90% CI has been determined.
Published: 2024
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2. An improved limit on the neutrinoless double-electron capture of $$^{36}$$ 36 Ar with GERDA

Author: GERDA Collaboration
Subjects: Astrophysics, QB460-466, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract: Abstract The GERmanium Detector Array (Gerda) experiment operated enriched high-purity germanium detectors in a liquid argon cryostat, which contains 0.33% of $$^{36}$$ 36 Ar, a candidate isotope for the two-neutrino double-electron capture (2 $$\nu $$ ν ECEC) and therefore for the neutrinoless double-electron capture (0 $$\nu $$ ν ECEC). If detected, this process would give evidence of lepton number violation and the Majorana nature of neutrinos. In the radiative 0 $$\nu $$ ν ECEC of $$^{36}$$ 36 Ar, a monochromatic photon is emitted with an energy of 429.88 keV, which may be detected by the Gerda germanium detectors. We searched for the $$^{36}$$ 36 Ar 0 $$\nu $$ ν ECEC with Gerda data, with a total live time of 4.34 year (3.08 year accumulated during Gerda Phase II and 1.26 year during Gerda Phase I). No signal was found and a 90% CL lower limit on the half-life of this process was established $$T_{1/2} >1.5\cdot 10^{22} $$ T 1 / 2 > 1.5 · 10 22 year.
Published: 2024
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3. Search for tri-nucleon decays of $$^{76}$$ 76 Ge in GERDA

Author: M. Agostini, A. Alexander, G. Araujo, A. M. Bakalyarov, M. Balata, I. Barabanov, L. Baudis, C. Bauer, S. Belogurov, A. Bettini, L. Bezrukov, V. Biancacci, E. Bossio, V. Bothe, R. Brugnera, A. Caldwell, S. Calgaro, C. Cattadori, A. Chernogorov, P.-J. Chiu, T. Comellato, V. D’Andrea, E. V. Demidova, A. Di Giacinto, N. Di Marco, E. Doroshkevich, F. Fischer, M. Fomina, A. Gangapshev, A. Garfagnini, C. Gooch, P. Grabmayr, V. Gurentsov, K. Gusev, J. Hakenmüller, S. Hemmer, W. Hofmann, M. Hult, L. V. Inzhechik, J. Janicskó Csáthy, J. Jochum, M. Junker, V. Kazalov, Y. Kermaïdic, H. Khushbakht, T. Kihm, K. Kilgus, I. V. Kirpichnikov, A. Klimenko, K. T. Knöpfle, O. Kochetov, V. N. Kornoukhov, P. Krause, V. V. Kuzminov, M. Laubenstein, M. Lindner, I. Lippi, A. Lubashevskiy, B. Lubsandorzhiev, G. Lutter, C. Macolino, B. Majorovits, W. Maneschg, L. Manzanillas, G. Marshall, M. Misiaszek, M. Morella, Y. Müller, I. Nemchenok, M. Neuberger, L. Pandola, K. Pelczar, L. Pertoldi, P. Piseri, A. Pullia, L. Rauscher, M. Redchuk, S. Riboldi, N. Rumyantseva, C. Sada, S. Sailer, F. Salamida, S. Schönert, J. Schreiner, M. Schütt, A.-K. Schütz, O. Schulz, M. Schwarz, B. Schwingenheuer, O. Selivanenko, E. Shevchik, M. Shirchenko, L. Shtembari, H. Simgen, A. Smolnikov, D. Stukov, S. Sullivan, A. A. Vasenko, A. Veresnikova, C. Vignoli, K. von Sturm, T. Wester, C. Wiesinger, M. Wojcik, E. Yanovich, B. Zatschler, I. Zhitnikov, S. V. Zhukov, D. Zinatulina, A. Zschocke, A. J. Zsigmond, K. Zuber, G. Zuzel, and GERDA collaboration
Subjects: Astrophysics, QB460-466, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract: Abstract We search for tri-nucleon decays of $$^{76}$$ 76 Ge in the dataset from the GERmanium Detector Array (GERDA) experiment. Decays that populate excited levels of the daughter nucleus above the threshold for particle emission lead to disintegration and are not considered. The ppp-, ppn-, and pnn-decays lead to $$^{73}$$ 73 Cu, $$^{73}$$ 73 Zn, and $$^{73}$$ 73 Ga nuclei, respectively. These nuclei are unstable and eventually proceed by the beta decay of $$^{73}$$ 73 Ga to $$^{73}$$ 73 Ge (stable). We search for the $$^{73}$$ 73 Ga decay exploiting the fact that it dominantly populates the 66.7 keV $$^{73m}$$ 73 m Ga state with half-life of 0.5 s. The nnn-decays of $$^{76}$$ 76 Ge that proceed via $$^{73m}$$ 73 m Ge are also included in our analysis. We find no signal candidate and place a limit on the sum of the decay widths of the inclusive tri-nucleon decays that corresponds to a lower lifetime limit of 1.2 $$\times $$ × 10 $$^{26}$$ 26 yr (90% credible interval). This result improves previous limits for tri-nucleon decays by one to three orders of magnitude.
Published: 2023
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4. Liquid argon light collection and veto modeling in GERDA Phase II

Author: M. Agostini, A. Alexander, G. R. Araujo, A. M. Bakalyarov, M. Balata, I. Barabanov, L. Baudis, C. Bauer, S. Belogurov, A. Bettini, L. Bezrukov, V. Biancacci, E. Bossio, V. Bothe, R. Brugnera, A. Caldwell, S. Calgaro, C. Cattadori, A. Chernogorov, P. -J. Chiu, T. Comellato, V. D’Andrea, E. V. Demidova, A. Di Giacinto, N. Di Marco, E. Doroshkevich, F. Fischer, M. Fomina, A. Gangapshev, A. Garfagnini, C. Gooch, P. Grabmayr, V. Gurentsov, K. Gusev, J. Hakenmüller, S. Hemmer, W. Hofmann, M. Hult, L. V. Inzhechik, J. Janicskó Csáthy, J. Jochum, M. Junker, V. Kazalov, Y. Kermaïdic, H. Khushbakht, T. Kihm, K. Kilgus, I. V. Kirpichnikov, A. Klimenko, K. T. Knöpfle, O. Kochetov, V. N. Kornoukhov, P. Krause, V. V. Kuzminov, M. Laubenstein, B. Lehnert, M. Lindner, I. Lippi, A. Lubashevskiy, B. Lubsandorzhiev, G. Lutter, C. Macolino, B. Majorovits, W. Maneschg, L. Manzanillas, G. Marshall, M. Miloradovic, R. Mingazheva, M. Misiaszek, M. Morella, Y. Müller, I. Nemchenok, M. Neuberger, L. Pandola, K. Pelczar, L. Pertoldi, P. Piseri, A. Pullia, L. Rauscher, M. Redchuk, S. Riboldi, N. Rumyantseva, C. Sada, S. Sailer, F. Salamida, S. Schönert, J. Schreiner, M. Schütt, A. -K. Schütz, O. Schulz, M. Schwarz, B. Schwingenheuer, O. Selivanenko, E. Shevchik, M. Shirchenko, L. Shtembari, H. Simgen, A. Smolnikov, D. Stukov, S. Sullivan, A. A. Vasenko, A. Veresnikova, C. Vignoli, K. von Sturm, A. Wegmann, T. Wester, C. Wiesinger, M. Wojcik, E. Yanovich, B. Zatschler, I. Zhitnikov, S. V. Zhukov, D. Zinatulina, A. Zschocke, A. J. Zsigmond, K. Zuber, G. Zuzel, and Gerda collaboration
Subjects: Astrophysics, QB460-466, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract: Abstract The ability to detect liquid argon scintillation light from within a densely packed high-purity germanium detector array allowed the Gerda experiment to reach an exceptionally low background rate in the search for neutrinoless double beta decay of $${}^{76}$$ 76 Ge. Proper modeling of the light propagation throughout the experimental setup, from any origin in the liquid argon volume to its eventual detection by the novel light read-out system, provides insight into the rejection capability and is a necessary ingredient to obtain robust background predictions. In this paper, we present a model of the Gerda liquid argon veto, as obtained by Monte Carlo simulations and constrained by calibration data, and highlight its application for background decomposition.
Published: 2023
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5. Pulse shape analysis in Gerda Phase II

Author: M. Agostini, G. Araujo, A. M. Bakalyarov, M. Balata, I. Barabanov, L. Baudis, C. Bauer, E. Bellotti, S. Belogurov, A. Bettini, L. Bezrukov, V. Biancacci, E. Bossio, V. Bothe, V. Brudanin, R. Brugnera, A. Caldwell, C. Cattadori, A. Chernogorov, T. Comellato, V. D’Andrea, E. V. Demidova, N. Di Marco, E. Doroshkevich, F. Fischer, M. Fomina, A. Gangapshev, A. Garfagnini, C. Gooch, P. Grabmayr, V. Gurentsov, K. Gusev, J. Hakenmüller, S. Hemmer, R. Hiller, W. Hofmann, J. Huang, M. Hult, L. V. Inzhechik, J. Janicskó Csáthy, J. Jochum, M. Junker, V. Kazalov, Y. Kermaïdic, H. Khushbakht, T. Kihm, K. Kilgus, A. Kirsch, I. V. Kirpichnikov, A. Klimenko, K. T. Knöpfle, O. Kochetov, V. N. Kornoukhov, P. Krause, V. V. Kuzminov, M. Laubenstein, A. Lazzaro, M. Lindner, I. Lippi, A. Lubashevskiy, B. Lubsandorzhiev, G. Lutter, C. Macolino, B. Majorovits, W. Maneschg, L. Manzanillas, M. Miloradovic, R. Mingazheva, M. Misiaszek, Y. Müller, I. Nemchenok, K. Panas, L. Pandola, K. Pelczar, L. Pertoldi, P. Piseri, A. Pullia, C. Ransom, L. Rauscher, M. Redchuk, S. Riboldi, N. Rumyantseva, C. Sada, F. Salamida, S. Schönert, J. Schreiner, M. Schütt, A. -K. Schütz, O. Schulz, M. Schwarz, B. Schwingenheuer, O. Selivanenko, E. Shevchik, M. Shirchenko, L. Shtembari, H. Simgen, A. Smolnikov, D. Stukov, A. A. Vasenko, A. Veresnikova, C. Vignoli, K. von Sturm, V. Wagner, T. Wester, C. Wiesinger, M. Wojcik, E. Yanovich, B. Zatschler, I. Zhitnikov, S. V. Zhukov, D. Zinatulina, A. Zschocke, A. J. Zsigmond, K. Zuber, G. Zuzel, and GERDA collaboration
Subjects: Astrophysics, QB460-466, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract: Abstract The GERmanium Detector Array (Gerda) collaboration searched for neutrinoless double- $$\beta $$ β decay in $$^{76}$$ 76 Ge using isotopically enriched high purity germanium detectors at the Laboratori Nazionali del Gran Sasso of INFN. After Phase I (2011–2013), the experiment benefited from several upgrades, including an additional active veto based on LAr instrumentation and a significant increase of mass by point-contact germanium detectors that improved the half-life sensitivity of Phase II (2015–2019) by an order of magnitude. At the core of the background mitigation strategy, the analysis of the time profile of individual pulses provides a powerful topological discrimination of signal-like and background-like events. Data from regular $$^{228}$$ 228 Th calibrations and physics data were both considered in the evaluation of the pulse shape discrimination performance. In this work, we describe the various methods applied to the data collected in Gerda Phase II corresponding to an exposure of 103.7 kg year. These methods suppress the background by a factor of about 5 in the region of interest around $$Q_{\beta \beta }= 2039$$ Q β β = 2039 keV, while preserving $$(81\pm 3)$$ ( 81 ± 3 ) % of the signal. In addition, an exhaustive list of parameters is provided which were used in the final data analysis.
Published: 2022
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6. Calibration of the Gerda experiment

Author: M. Agostini, G. Araujo, A. M. Bakalyarov, M. Balata, I. Barabanov, L. Baudis, C. Bauer, E. Bellotti, S. Belogurov, A. Bettini, L. Bezrukov, V. Biancacci, E. Bossio, V. Bothe, V. Brudanin, R. Brugnera, A. Caldwell, C. Cattadori, A. Chernogorov, T. Comellato, V. D’Andrea, E. V. Demidova, N. Di Marco, E. Doroshkevich, F. Fischer, M. Fomina, A. Gangapshev, A. Garfagnini, C. Gooch, P. Grabmayr, V. Gurentsov, K. Gusev, J. Hakenmüller, S. Hemmer, R. Hiller, W. Hofmann, J. Huang, M. Hult, L. V. Inzhechik, J. Janicskó Csáthy, J. Jochum, M. Junker, V. Kazalov, Y. Kermaïdic, H. Khushbakht, T. Kihm, I. V. Kirpichnikov, A. Klimenko, R. Kneißl, K. T. Knöpfle, O. Kochetov, V. N. Kornoukhov, P. Krause, V. V. Kuzminov, M. Laubenstein, M. Lindner, I. Lippi, A. Lubashevskiy, B. Lubsandorzhiev, G. Lutter, C. Macolino, B. Majorovits, W. Maneschg, L. Manzanillas, M. Miloradovic, R. Mingazheva, M. Misiaszek, P. Moseev, Y. Müller, I. Nemchenok, L. Pandola, K. Pelczar, L. Pertoldi, P. Piseri, A. Pullia, C. Ransom, L. Rauscher, S. Riboldi, N. Rumyantseva, C. Sada, F. Salamida, S. Schönert, J. Schreiner, M. Schütt, A-K. Schütz, O. Schulz, M. Schwarz, B. Schwingenheuer, O. Selivanenko, E. Shevchik, M. Shirchenko, L. Shtembari, H. Simgen, A. Smolnikov, D. Stukov, A. A. Vasenko, A. Veresnikova, C. Vignoli, K. von Sturm, T. Wester, C. Wiesinger, M. Wojcik, E. Yanovich, B. Zatschler, I. Zhitnikov, S. V. Zhukov, D. Zinatulina, A. Zschocke, A. J. Zsigmond, K. Zuber, G. Zuzel, and Gerda Collaboration
Subjects: Astrophysics, QB460-466, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract: Abstract The GERmanium Detector Array (Gerda) collaboration searched for neutrinoless double- $$\beta $$ β decay in $$^{76}$$ 76 Ge with an array of about 40 high-purity isotopically-enriched germanium detectors. The experimental signature of the decay is a monoenergetic signal at $$Q_{\beta \beta }$$ Q β β $$=2039.061(7)$$ = 2039.061 ( 7 ) keV in the measured summed energy spectrum of the two emitted electrons. Both the energy reconstruction and resolution of the germanium detectors are crucial to separate a potential signal from various backgrounds, such as neutrino-accompanied double- $$\beta $$ β decays allowed by the Standard Model. The energy resolution and stability were determined and monitored as a function of time using data from regular $$^{228}$$ 228 Th calibrations. In this work, we describe the calibration process and associated data analysis of the full Gerda dataset, tailored to preserve the excellent resolution of the individual germanium detectors when combining data over several years.
Published: 2021
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7. Characterization of inverted coaxial $$^{76}$$ 76 Ge detectors in GERDA for future double- $$\beta $$ β decay experiments

Author: M. Agostini, G. Araujo, A. M. Bakalyarov, M. Balata, I. Barabanov, L. Baudis, C. Bauer, E. Bellotti, S. Belogurov, A. Bettini, L. Bezrukov, V. Biancacci, E. Bossio, V. Bothe, V. Brudanin, R. Brugnera, A. Caldwell, C. Cattadori, A. Chernogorov, T. Comellato, V. D’Andrea, E. V. Demidova, N. Di Marco, E. Doroshkevich, F. Fischer, M. Fomina, A. Gangapshev, A. Garfagnini, C. Gooch, P. Grabmayr, V. Gurentsov, K. Gusev, J. Hakenmüller, S. Hemmer, W. Hofmann, J. Huang, M. Hult, L. V. Inzhechik, J. Janicskó Csáthy, J. Jochum, M. Junker, V. Kazalov, Y. Kermaïdic, H. Khushbakht, T. Kihm, I. V. Kirpichnikov, A. Klimenko, R. Kneißl, K. T. Knöpfle, O. Kochetov, V. N. Kornoukhov, P. Krause, V. V. Kuzminov, M. Laubenstein, M. Lindner, I. Lippi, A. Lubashevskiy, B. Lubsandorzhiev, G. Lutter, C. Macolino, B. Majorovits, W. Maneschg, L. Manzanillas, M. Miloradovic, R. Mingazheva, M. Misiaszek, P. Moseev, Y. Müller, I. Nemchenok, L. Pandola, K. Pelczar, L. Pertoldi, P. Piseri, A. Pullia, C. Ransom, L. Rauscher, S. Riboldi, N. Rumyantseva, C. Sada, F. Salamida, S. Schönert, J. Schreiner, M. Schütt, A.-K. Schütz, O. Schulz, M. Schwarz, B. Schwingenheuer, O. Selivanenko, E. Shevchik, M. Shirchenko, L. Shtembari, H. Simgen, A. Smolnikov, D. Stukov, A. A. Vasenko, A. Veresnikova, C. Vignoli, K. von Sturm, T. Wester, C. Wiesinger, M. Wojcik, E. Yanovich, B. Zatschler, I. Zhitnikov, S. V. Zhukov, D. Zinatulina, A. Zschocke, A. J. Zsigmond, K. Zuber, G. Zuzel, and Gerda Collaboration
Subjects: Astrophysics, QB460-466, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract: Abstract Neutrinoless double- $$\beta $$ β decay of $$^{76}$$ 76 Ge is searched for with germanium detectors where source and detector of the decay are identical. For the success of future experiments it is important to increase the mass of the detectors. We report here on the characterization and testing of five prototype detectors manufactured in inverted coaxial (IC) geometry from material enriched to 88% in $$^{76}$$ 76 Ge. IC detectors combine the large mass of the traditional semi-coaxial Ge detectors with the superior resolution and pulse shape discrimination power of point contact detectors which exhibited so far much lower mass. Their performance has been found to be satisfactory both when operated in vacuum cryostat and bare in liquid argon within the Gerda setup. The measured resolutions at the Q-value for double- $$\beta $$ β decay of $$^{76}$$ 76 Ge ( $$Q_{\beta \beta }$$ Q β β = 2039 keV) are about 2.1 keV full width at half maximum in vacuum cryostat. After 18 months of operation within the ultra-low background environment of the GERmanium Detector Array (Gerda) experiment and an accumulated exposure of 8.5 kg $$\cdot $$ · year, the background index after analysis cuts is measured to be $$4.9^{+7.3}_{-3.4}\times 10^{-4} \ \text {counts}/(\text {keV} \cdot \text {kg} \cdot \text {year})$$ 4 . 9 - 3.4 + 7.3 × 10 - 4 counts / ( keV · kg · year ) around $$Q_{\beta \beta }$$ Q β β . This work confirms the feasibility of IC detectors for the next-generation experiment Legend.
Published: 2021
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8. Characterization of 30 $$^{76}$$ 76 Ge enriched Broad Energy Ge detectors for GERDA Phase II

Author: M. Agostini, A. M. Bakalyarov, E. Andreotti, M. Balata, I. Barabanov, L. Baudis, N. Barros, C. Bauer, E. Bellotti, S. Belogurov, G. Benato, A. Bettini, L. Bezrukov, T. Bode, D. Borowicz, V. Brudanin, R. Brugnera, D. Budjáš, A. Caldwell, C. Cattadori, A. Chernogorov, V. D’Andrea, E. V. Demidova, N. Di Marco, A. Domula, E. Doroshkevich, V. Egorov, R. Falkenstein, K. Freund, A. Gangapshev, A. Garfagnini, C. Gooch, P. Grabmayr, V. Gurentsov, K. Gusev, J. Hakenmüller, A. Hegai, M. Heisel, S. Hemmer, R. Hiller, W. Hofmann, M. Hult, L. V. Inzhechik, J. Janicskó Csáthy, J. Jochum, M. Junker, V. Kazalov, Y. Kermaïdic, T. Kihm, I. V. Kirpichnikov, A. Kirsch, A. Kish, A. Klimenko, R. Kneißl, K. T. Knöpfle, O. Kochetov, V. N. Kornoukhov, V. V. Kuzminov, M. Laubenstein, A. Lazzaro, B. Lehnert, Y. Liao, M. Lindner, I. Lippi, A. Lubashevskiy, B. Lubsandorzhiev, G. Lutter, C. Macolino, B. Majorovits, W. Maneschg, G. Marissens, M. Miloradovic, R. Mingazheva, M. Misiaszek, P. Moseev, I. Nemchenok, K. Panas, L. Pandola, K. Pelczar, A. Pullia, C. Ransom, S. Riboldi, N. Rumyantseva, C. Sada, F. Salamida, M. Salathe, C. Schmitt, B. Schneider, S. Schönert, A.-K. Schütz, O. Schulz, B. Schwingenheuer, O. Selivanenko, E. Shevchik, M. Shirchenko, H. Simgen, A. Smolnikov, L. Stanco, L. Vanhoefer, A. A. Vasenko, A. Veresnikova, K. von Sturm, V. Wagner, A. Wegmann, T. Wester, C. Wiesinger, M. Wojcik, E. Yanovich, I. Zhitnikov, S. V. Zhukov, D. Zinatulina, A. J. Zsigmond, K. Zuber, G. Zuzel, and GERDA Collaboration
Subjects: Astrophysics, QB460-466, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract: Abstract 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 $$^{76}$$ 76 Ge into $$^{76}$$ 76 Se+2e$$^-$$ - . Gerda has been conceived in two phases. Phase II, which started in December 2015, features several novelties including 30 new 76Ge 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.
Published: 2019
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9. Upgrade for Phase II of the Gerda experiment

Author: GERDA Collaboration, M. Agostini, A. M. Bakalyarov, M. Balata, I. Barabanov, L. Baudis, C. Bauer, E. Bellotti, S. Belogurov, S. T. Belyaev, G. Benato, A. Bettini, L. Bezrukov, T. Bode, D. Borowicz, V. Brudanin, R. Brugnera, A. Caldwell, C. Cattadori, A. Chernogorov, V. D’Andrea, E. V. Demidova, N. Di Marco, A. Domula, E. Doroshkevich, V. Egorov, R. Falkenstein, N. Frodyma, A. Gangapshev, A. Garfagnini, P. Grabmayr, V. Gurentsov, K. Gusev, J. Hakenmüller, A. Hegai, M. Heisel, S. Hemmer, R. Hiller, W. Hofmann, M. Hult, L. V. Inzhechik, L. Ioannucci, J. Janicskó Csáthy, J. Jochum, M. Junker, V. Kazalov, Y. Kermaïdic, T. Kihm, I. V. Kirpichnikov, A. Kirsch, A. Kish, A. Klimenko, R. Kneißl, K. T. Knöpfle, O. Kochetov, V. N. Kornoukhov, V. V. Kuzminov, M. Laubenstein, A. Lazzaro, V. I. Lebedev, B. Lehnert, M. Lindner, I. Lippi, A. Lubashevskiy, B. Lubsandorzhiev, G. Lutter, C. Macolino, B. Majorovits, W. Maneschg, E. Medinaceli, M. Miloradovic, R. Mingazheva, M. Misiaszek, P. Moseev, I. Nemchenok, S. Nisi, K. Panas, L. Pandola, K. Pelczar, A. Pullia, C. Ransom, S. Riboldi, N. Rumyantseva, C. Sada, F. Salamida, M. Salathe, C. Schmitt, B. Schneider, S. Schönert, J. Schreiner, A-K. Schütz, O. Schulz, B. Schwingenheuer, O. Selivanenko, E. Shevchik, M. Shirchenko, H. Simgen, A. Smolnikov, L. Stanco, L. Vanhoefer, A. A. Vasenko, A. Veresnikova, K. von Sturm, V. Wagner, A. Wegmann, T. Wester, C. Wiesinger, M. Wojcik, E. Yanovich, I. Zhitnikov, S. V. Zhukov, D. Zinatulina, A. J. Zsigmond, K. Zuber, and G. Zuzel
Subjects: Astrophysics, QB460-466, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract: Abstract The Gerda collaboration is performing a sensitive search for neutrinoless double beta decay of $$^{76}\hbox {Ge}$$ 76Ge at the INFN Laboratori Nazionali del Gran Sasso, Italy. The upgrade of the Gerda experiment from Phase I to Phase II has been concluded in December 2015. The first Phase II data release shows that the goal to suppress the background by one order of magnitude compared to Phase I has been achieved. Gerda is thus the first experiment that will remain “background-free” up to its design exposure ($$\hbox {100 kg}~\hbox {year}$$ 100 kgyear ). It will reach thereby a half-life sensitivity of more than $$10^{26}$$ 1026 year within 3 years of data collection. This paper describes in detail the modifications and improvements of the experimental setup for Phase II and discusses the performance of individual detector components.
Published: 2018
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10. An improved limit on the neutrinoless double-electron capture of $^{36}$Ar with GERDA

Author: GERDA Collaboration, Agostini, M., Alexander, A., Araujo, G. R., Bakalyarov, A. M., Balata, M., Barabanov, I., Baudis, L., Bauer, C., Belogurov, S., Bettini, A., Bezrukov, L., Biancacci, V., Bossio, E., Bothe, V., Brudanin, V., Brugnera, R., Caldwell, A., Cattadori, C., Chernogorov, A., Comellato, T., D'Andrea, V., Demidova, E. V., Di Marco, N., Doroshkevich, E., Fischer, F., Fomina, M., Gangapshev, A., Garfagnini, A., Gooch, C., Grabmayr, P., Gurentsov, V., Gusev, K., Hakenmüller, J., Hemmer, S., Hofmann, W., Huang, J., Hult, M., Inzhechik, L. V., Csáthy, J. Janicskó, Jochum, J., Junker, M., Kazalov, V., Kermaïdic, Y., Khushbakht, H., Kihm, T., Kilgus, K., Kirpichnikov, I. V., Klimenko, A., Kneißl, R., Knöpfle, K. T., Kochetov, O., Kornoukhov, V. N., Korošec, M., Krause, P., Kuzminov, V. V., Laubenstein, M., Lindner, M., Lippi, I., Lubashevskiy, A., Lubsandorzhiev, B., Lutter, G., Macolino, C., Majorovits, B., Maneschg, W., Manzanillas, L., Marshall, G., Misiaszek, M., Morella, M., Müller, Y., Nemchenok, I., Pandola, L., Pelczar, K., Pertoldi, L., Piseri, P., Pullia, A., Ransom, C., Rauscher, L., Redchuk, M., Riboldi, S., Rumyantseva, N., Sada, C., Salamida, F., Schönert, S., Schreiner, J., Schütt, M., Schütz, A-K., Schulz, O., Schwarz, M., Schwingenheuer, B., Selivanenko, O., Shevchik, E., Shirchenko, M., Shtembari, L., Simgen, H., Smolnikov, A., Stukov, D., Vasenko, A. A., Veresnikova, A., Vignoli, C., von Sturm, K., Wester, T., Wiesinger, C., Wojcik, M., Yanovich, E., Zatschler, B., Zhitnikov, I., Zhukov, S. V., Zinatulina, D., Zschocke, A., Zsigmond, A. J., Zuber, K., and Zuzel, G.
Subjects: Nuclear Experiment
Abstract: The GERmanium Detector Array (GERDA) experiment operated enriched high-purity germanium detectors in a liquid argon cryostat, which contains 0.33% of $^{36}$Ar, a candidate isotope for the two-neutrino double-electron capture (2$\nu$ECEC) and therefore for the neutrinoless double-electron capture (0$\nu$ECEC). If detected, this process would give evidence of lepton number violation and the Majorana nature of neutrinos. In the radiative 0$\nu$ECEC of $^{36}$Ar, a monochromatic photon is emitted with an energy of 429.88 keV, which may be detected by the GERDA germanium detectors. We searched for the $^{36}$Ar 0$\nu$ECEC with GERDA data, with a total live time of 4.34 yr (3.08 yr accumulated during GERDA Phase II and 1.26 yr during GERDA Phase I). No signal was found and a 90% C.L. lower limit on the half-life of this process was established T$_{1/2}$ > 1.5x10$^{22}$ yr, Comment: 10 pages, 5 figures, 1 table
Published: 2023

11. Final Results of GERDA on the Two-Neutrino Double-$\beta$ Decay Half-Life of $^{76}$Ge

Author: GERDA collaboration, Agostini, M., Alexander, A., Araujo, G. R., Bakalyarov, A. M., Balata, M., Barabanov, I., Baudis, L., Bauer, C., Belogurov, S., Bettini, A., Bezrukov, L., Biancacci, V., Bossio, E., Bothe, V., Brugnera, R., Caldwell, A., Calgaro, S., Cattadori, C., Chernogorov, A., Chiu, P. -J., Comellato, T., D'Andrea, V., Demidova, E. V., Di Giacinto, A., Di Marco, N., Doroshkevich, E., Fischer, F., Fomina, M., Gangapshev, A., Garfagnini, A., Gooch, C., Grabmayr, P., Gurentsov, V., Gusev, K., Hackenmüller, S., Hemmer, S., Hofmann, W., Huang, J., Hult, M., Inzhechik, L. V., Csáthy, J. Janicskó, Jochum, J., Junker, M., Kazalov, V., Kermaïdic, Y., Khushbakht, H., Kihm, T., Kilgus, K., Kirpichnikov, I. V., Klimenko, A., Knöpfle, K. T., Kochetov, O., Kornoukhov, V. N., Krause, P., Kuzminov, V. V., Laubenstein, M., Lehnert, B., Lindner, M., Lippi, I., Lubashevskiy, A., Lubsandorzhiev, B., Lutter, G., Macolino, C., Majorovits, B., Maneschg, W., Manzanillas, L., Marshall, G., Miloradovic, M., Mingazheva, R., Misiaszek, M., Morella, M., Müller, Y., Nemchenok, I., Neuberger, M., Pandola, L., Pelczar, K., Pertoldi, L., Piseri, P., Pullia, A., Ransom, C., Rauscher, L., Redchuk, M., Riboldi, S., Rumyantseva, N., Sada, C., Sailer, S., Salamida, F., Schönert, S., Schreiner, J., Schütt, M., Schütz, A. -K., Schulz, O., Schwarz, M., Schwingenheuer, B., Selivanenko, O., Shevchik, E., Shirchenko, M., Shtembari, L., Simgen, H., Smolnikov, A., Stukov, D., Sullivan, S., Vasenko, A. A., Veresnikova, A., Vignoli, C., von Sturm, K., Wester, T., Wiesinger, C., Wojcik, M., Yanovich, E., Zatschler, B., Zhitnikov, I., Zhukov, S. V., Zinatulina, D., Zschocke, A., Zsigmond, A. J., Zuber, K., and Zuzel, G.
Subjects: Nuclear Experiment
Abstract: We present the measurement of the two-neutrino double-$\beta$ decay rate of $^{76}$Ge performed with the GERDA Phase II experiment. With a subset of the entire GERDA exposure, 11.8 kg$\cdot$yr, the half-life of the process has been determined: $T^{2\nu}_{1/2} = (2.022 \pm 0.018_{stat} \pm 0.038_{sys})\times10^{21}$ yr. This is the most precise determination of the $^{76}$Ge two-neutrino double-$\beta$ decay half-life and one of the most precise measurements of a double-$\beta$ decay process. The relevant nuclear matrix element can be extracted: $M^{2\nu}_{\text{eff}} = (0.101\pm0.001).$, Comment: 7 pages, 4 figures, 2 tables
Published: 2023
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12. Search for tri-nucleon decays of $^{76}$Ge in GERDA

Author: GERDA collaboration, Agostini, M., Alexander, A., Araujo, G., Bakalyarov, A. M., Balata, M., Barabanov, I., Baudis, L., Bauer, C., Belogurov, S., Bettini, A., Bezrukov, L., Biancacci, V., Bossio, E., Bothe, V., Brugnera, R., Caldwell, A., Calgaro, S., Cattadori, C., Chernogorov, A., Chiu, P. -J., Comellato, T., D'Andrea, V., Demidova, E. V., Di Giacinto, A., Di Marco, N., Doroshkevich, E., Fischer, F., Fomina, M., Gangapshev, A., Garfagnini, A., Gooch, C., Grabmayr, P., Gurentsov, V., Gusev, K., Hakenmüller, J., Hemmer, S., Hofmann, W., Hult, M., Inzhechik, L. V., Csáthy, J. Janicskó, Jochum, J., Junker, M., Kazalov, V., Kermaïdic, Y., Khushbakht, H., Kihm, T., Kilgus, K., Kirpichnikov, I. V., Klimenko, A., Knöpfle, K. T., Kochetov, O., Kornoukhov, V. N., Krause, P., Kuzminov, V. V., Laubenstein, M., Lindner, M., Lippi, I., Lubashevskiy, A., Lubsandorzhiev, B., Lutter, G., Macolino, C., Majorovits, B., Maneschg, W., Manzanillas, L., Marshall, G., Misiaszek, M., Morella, M., Müller, Y., Nemchenok, I., Neuberger, M., Pandola, L., Pelczar, K., Pertoldi, L., Piseri, P., Pullia, A., Rauscher, L., Redchuk, M., Riboldi, S., Rumyantseva, N., Sada, C., Sailer, S., Salamida, F., Schönert, S., Schreiner, J., Schütt, M., Schütz, A-K., Schulz, O., Schwarz, M., Schwingenheuer, B., Selivanenko, O., Shevchik, E., Shirchenko, M., Shtembari, L., Simgen, H., Smolnikov, A., Stukov, D., Sullivan, S., Vasenko, A. A., Veresnikova, A., Vignoli, C., von Sturm, K., Wester, T., Wiesinger, C., Wojcik, M., Yanovich, E., Zatschler, B., Zhitnikov, I., Zhukov, S. V., Zinatulina, D., Zschocke, A., Zsigmond, A. J., Zuber, K., and Zuzel, G.
Subjects: Nuclear Experiment
Abstract: We search for tri-nucleon decays of $^{76}$Ge in the dataset from the GERmanium Detector Array (GERDA) experiment. Decays that populate excited levels of the daughter nucleus above the threshold for particle emission lead to disintegration and are not considered. The ppp-, ppn-, and pnn-decays lead to $^{73}$Cu, $^{73}$Zn, and $^{73}$Ga nuclei, respectively. These nuclei are unstable and eventually proceed by the beta decay of $^{73}$Ga to $^{73}$Ge (stable). We search for the $^{73}$Ga decay exploiting the fact that it dominantly populates the 66.7 keV $^{73m}$Ga state with half-life of 0.5 s. The nnn-decays of $^{76}$Ge that proceed via $^{73m}$Ge are also included in our analysis. We find no signal candidate and place a limit on the sum of the decay widths of the inclusive tri-nucleon decays that corresponds to a lower lifetime limit of 1.2x10$^{26}$ yr (90% credible interval). This result improves previous limits for tri-nucleon decays by one to three orders of magnitude., Comment: 8 pages, 9 figures, 3 tables
Published: 2023
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13. Liquid argon light collection and veto modeling in GERDA Phase II

Author: GERDA collaboration, Agostini, M., Alexander, A., Araujo, G. R., Bakalyarov, A. M., Balata, M., Barabanov, I., Baudis, L., Bauer, C., Belogurov, S., Bettini, A., Bezrukov, L., Biancacci, V., Bossio, E., Bothe, V., Brugnera, R., Caldwell, A., Calgaro, S., Cattadori, C., Chernogorov, A., Chiu, P-J., Comellato, T., D'Andrea, V., Demidova, E. V., Di Giacinto, A., Di Marco, N., Doroshkevich, E., Fischer, F., Fomina, M., Gangapshev, A., Garfagnini, A., Gooch, C., Grabmayr, P., Gurentsov, V., Gusev, K., Hakenmüller, J., Hemmer, S., Hofmann, W., Hult, M., Inzhechik, L. V., Csáthy, J. Janicskó, Jochum, J., Junker, M., Kazalov, V., Kermaïdic, Y., Khushbakht, H., Kihm, T., Kilgus, K., Kirpichnikov, I. V., Klimenko, A., Knöpfle, K. T., Kochetov, O., Kornoukhov, V. N., Krause, P., Kuzminov, V. V., Laubenstein, M., Lehnert, B., Lindner, M., Lippi, I., Lubashevskiy, A., Lubsandorzhiev, B., Lutter, G., Macolino, C., Majorovits, B., Maneschg, W., Manzanillas, L., Marshall, G., Miloradovic, M., Mingazheva, R., Misiaszek, M., Morella, M., Müller, Y., Nemchenok, I., Neuberger, M., Pandola, L., Pelczar, K., Pertoldi, L., Piseri, P., Pullia, A., Rauscher, L., Redchuk, M., Riboldi, S., Rumyantseva, N., Sada, C., Sailer, S., Salamida, F., Schönert, S., Schreiner, J., Schütt, M., Schütz, A-K., Schulz, O., Schwarz, M., Schwingenheuer, B., Selivanenko, O., Shevchik, E., Shirchenko, M., Shtembari, L., Simgen, H., Smolnikov, A., Stukov, D., Sullivan, S., Vasenko, A. A., Veresnikova, A., Vignoli, C., von Sturm, K., Wegmann, A., Wester, T., Wiesinger, C., Wojcik, M., Yanovich, E., Zatschler, B., Zhitnikov, I., Zhukov, S. V., Zinatulina, D., Zschocke, A., Zsigmond, A. J., Zuber, K., and Zuzel, G.
Subjects: Physics - Instrumentation and Detectors, High Energy Physics - Experiment, Nuclear Experiment
Abstract: The ability to detect liquid argon scintillation light from within a densely packed high-purity germanium detector array allowed the GERDA experiment to reach an exceptionally low background rate in the search for neutrinoless double beta decay of $^{76}$Ge. Proper modeling of the light propagation throughout the experimental setup, from any origin in the liquid argon volume to its eventual detection by the novel light read-out system, provides insight into the rejection capability and is a necessary ingredient to obtain robust background predictions. In this paper, we present a model of the GERDA liquid argon veto, as obtained by Monte Carlo simulations and constrained by calibration data, and highlight its application for background decomposition.
Published: 2022
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14. Search for exotic physics in double-$\beta$ decays with GERDA Phase II

Author: The GERDA collaboration, Agostini, M., Alexander, A., Araujo, G., Bakalyarov, A. M., Balata, M., Barabanov, I., Baudis, L., Bauer, C., Belogurov, S., Bettini, A., Bezrukov, L., Biancacci, V., Bossio, E., Bothe, V., Brugnera, R., Caldwell, A., Cattadori, C., Chernogorov, A., Comellato, T., D'Andrea, V., Demidova, E. V., Di Giacinto, A., Di Marco, N., Doroshkevich, E., Fischer, F., Fomina, M., Gangapshev, A., Garfagnini, A., Gooch, C., Grabmayr, P., Gurentsov, V., Gusev, K., Hakenmüller, J., Hemmer, S., Hofmann, W., Huang, J., Hult, M., Inzhechik, L. V., Csáthy, J. Janicskó, Jochum, J., Junker, M., Kazalov, V., Kermaïdic, Y., Khushbakht, H., Kihm, T., Kilgus, K., Kirpichnikov, I. V., Klimenko, A., Knöpfle, K. T., Kochetov, O., Kornoukhov, V. N., Krause, P., Kuzminov, V. V., Laubenstein, M., Lindner, M., Lippi, I., Lubashevskiy, A., Lubsandorzhiev, B., Lutter, G., Macolino, C., Majorovits, B., Maneschg, W., Manzanillas, L., Marshall, G., Miloradovic, M., Mingazheva, R., Misiaszek, M., Morella, M., Müller, Y., Nemchenok, I., Pandola, L., Pelczar, K., Pertoldi, L., Piseri, P., Pullia, A., Ransom, C., Rauscher, L., Redchuk, M., Riboldi, S., Rumyantseva, N., Sada, C., Sailer, S., Salamida, F., Schönert, S., Schreiner, J., Schütt, M., Schütz, A. -K., Schulz, O., Schwarz, M., Schwingenheuer, B., Selivanenko, O., Shevchik, E., Shirchenko, M., Shtembari, L., Simgen, H., Smolnikov, A., Stukov, D., Vasenko, A. A., Veresnikova, A., Vignoli, C., von Sturm, K., Wester, T., Wiesinger, C., Wojcik, M., Yanovich, E., Zatschler, B., Zhitnikov, I., Zhukov, S. V., Zinatulina, D., Zschocke, A., Zsigmond, A. J., Zuber, K., and Zuzel, G.
Subjects: Nuclear Experiment, High Energy Physics - Experiment
Abstract: A search for Beyond the Standard Model double-$\beta$ decay modes of $^{76}$Ge has been performed with data collected during the Phase II of the GERmanium Detector Array (GERDA) experiment, located at Laboratori Nazionali del Gran Sasso of INFN (Italy). Improved limits on the decays involving Majorons have been obtained, compared to previous experiments with $^{76}$Ge, with half-life values on the order of 10$^{23}$ yr. For the first time with $^{76}$Ge, limits on Lorentz invariance violation effects in double-$\beta$ decay have been obtained. The isotropic coefficient $\mathring{a}_\text{of}^{(3)}$, which embeds Lorentz violation in double-$\beta$ decay, has been constrained at the order of $10^{-6}$ GeV. We also set the first experimental limits on the search for light exotic fermions in double-$\beta$ decay, including sterile neutrinos.
Published: 2022

15. Pulse shape analysis in GERDA Phase II

Author: The GERDA collaboration, Agostini, M., Araujo, G., Bakalyarov, A. M., Balata, M., Barabanov, I., Baudis, L., Bauer, C., Bellotti, E., Belogurov, S., Bettini, A., Bezrukov, L., Biancacci, V., Bossio, E., Bothe, V., Brudanin, V., Brugnera, R., Caldwell, A., Cattadori, C., Chernogorov, A., Comellato, T., D'Andrea, V., Demidova, E. V., Di Marco, N., Doroshkevich, E., Fischer, F., Fomina, M., Gangapshev, A., Garfagnini, A., Gooch, C., Grabmayr, P., Gurentsov, V., Gusev, K., Hakenmüller, J., Hemmer, S., Hiller, R., Hofmann, W., Huang, J., Hult, M., Inzhechik, L. V., Csáthy, J. Janicskó, Jochum, J., Junker, M., Kazalov, V., Kermaïdic, Y., Khushbakht, H., Kihm, T., Kilgus, K., Kirsch, A., Kirpichnikov, I. V., Klimenko, A., Knöpfle, K. T., Kochetov, O., Kornoukhov, V. N., Krause, P., Kuzminov, V. V., Laubenstein, M., Lazzaro, A., Lindner, M., Lippi, I., Lubashevskiy, A., Lubsandorzhiev, B., Lutter, G., Macolino, C., Majorovits, B., Maneschg, W., Manzanillas, L., Miloradovic, M., Mingazheva, R., Misiaszek, M., Müller, Y., Nemchenok, I., Panas, K., Pandola, L., Pelczar, K., Pertoldi, L., Piseri, P., Pullia, A., Ransom, C., Rauscher, L., Redchuk, M., Riboldi, S., Rumyantseva, N., Sada, C., Salamida, F., Schönert, S., Schreiner, J., Schütt, M., Schütz, A. -K., Schulz, O., Schwarz, M., Schwingenheuer, B., Selivanenko, O., Shevchik, E., Shirchenko, M., Shtembari, L., Simgen, H., Smolnikov, A., Stukov, D., Vasenko, A. A., Veresnikova, A., Vignoli, C., von Sturm, K., Wagner, V., Wester, T., Wiesinger, C., Wojcik, M., Yanovich, E., Zatschler, B., Zhitnikov, I., Zhukov, S. V., Zinatulina, D., Zschocke, A., Zsigmond, A. J., Zuber, K., and Zuzel, G.
Subjects: Physics - Instrumentation and Detectors, Nuclear Experiment
Abstract: The GERmanium Detector Array (GERDA) collaboration searched for neutrinoless double-$\beta$ decay in $^{76}$Ge using isotopically enriched high purity germanium detectors at the Laboratori Nazionali del Gran Sasso of INFN. After Phase I (2011-2013), the experiment benefited from several upgrades, including an additional active veto based on LAr instrumentation and a significant increase of mass by point-contact germanium detectors that improved the half-life sensitivity of Phase II (2015-2019) by an order of magnitude. At the core of the background mitigation strategy, the analysis of the time profile of individual pulses provides a powerful topological discrimination of signal-like and background-like events. Data from regular $^{228}$Th calibrations and physics data were both considered in the evaluation of the pulse shape discrimination performance. In this work, we describe the various methods applied to the data collected in GERDA Phase II corresponding to an exposure of 103.7 kg$\cdot$yr. These methods suppress the background by a factor of about 5 in the region of interest around Q$_{\beta\beta}$ = 2039 keV, while preserving (81$\pm$3)% of the signal. In addition, an exhaustive list of parameters is provided which were used in the final data analysis.
Published: 2022
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16. Characterization of inverted coaxial $^{76}$Ge detectors in GERDA for future double-$\beta$ decay experiments

Author: GERDA collaboration, Agostini, M., Araujo, G. R., Bakalyarov, A. M., Balata, M., Barabanov, I., Baudis, L., Bauer, C., Bellotti, E., Belogurov, S., Bettini, A., Bezrukov, L., Biancacci, V., Bossio, E., Bothe, V., Brudanin, V., Brugnera, R., Caldwell, A., Cattadori, C., Chernogorov, A., Comellato, T., D'Andrea, V., Demidova, E. V., Di Marco, N., Doroshkevich, E., Fischer, F., Fomina, M., Gangapshev, A., Garfagnini, A., Gooch, C., Grabmayr, P., Gurentsov, V., Gusev, K., Hakenmüller, J., Hemmer, S., Hofmann, W., Huang, J., Hult, M., Inzhechik, L. V., Csáthy, J. Janicskó, Jochum, J., Junker, M., Kazalov, V., Kermaïdic, Y., Khushbakht, H., Kihm, T., Kirpichnikov, I. V., Klimenko, A., Kneißl, R., Knöpfle, K. T., Kochetov, O., Kornoukhov, V. N., Krause, P., Kuzminov, V. V., Laubenstein, M., Lindner, M., Lippi, I., Lubashevskiy, A., Lubsandorzhiev, B., Lutter, G., Macolino, C., Majorovits, B., Maneschg, W., Manzanillas, L., Miloradovic, M., Mingazheva, R., Misiaszek, M., Moseev, P., Müller, Y., Nemchenok, I., Pandola, L., Pelczar, K., Pertoldi, L., Piseri, P., Pullia, A., Ransom, C., Rauscher, L., Riboldi, S., Rumyantseva, N., Sada, C., Salamida, F., Schönert, S., Schreiner, J., Schütt, M., Schütz, A. -K., Schulz, O., Schwarz, M., Schwingenheuer, B., Selivanenko, O., Shevchik, E., Shirchenko, M., Shtembari, L., Simgen, H., Smolnikov, A., Stukov, D., Vasenko, A. A., Veresnikova, A., Vignoli, C., von Sturm, K., Wester, T., Wiesinger, C., Wojcik, M., Yanovich, E., Zatschler, B., Zhitnikov, I., Zhukov, S. V., Zinatulina, D., Zschocke, A., Zsigmond, A. J., Zuber, K., and Zuzel, G.
Subjects: Physics - Instrumentation and Detectors, Nuclear Experiment
Abstract: Neutrinoless double-$\beta$ decay of $^{76}$Ge is searched for with germanium detectors where source and detector of the decay are identical. For the success of future experiments it is important to increase the mass of the detectors. We report here on the characterization and testing of five prototype detectors manufactured in inverted coaxial (IC) geometry from material enriched to 88% in $^{76}$Ge. IC detectors combine the large mass of the traditional semi-coaxial Ge detectors with the superior resolution and pulse shape discrimination power of point contact detectors which exhibited so far much lower mass. Their performance has been found to be satisfactory both when operated in vacuum cryostat and bare in liquid argon within the GERDA setup. The measured resolutions at the Q-value for double-$\beta$ decay of $^{76}$Ge (Q$_{\beta\beta}$ = 2039 keV) are about 2.1 keV full width at half maximum in vacuum cryostat. After 18 months of operation within the ultra-low background environment of the GERmanium Detector Array (GERDA) experiment and an accumulated exposure of 8.5 kg$\cdot$yr, the background index after analysis cuts is measured to be $4.9^{+7.3}_{-3.4}\times 10^{-4}$ counts /(keV$\cdot$kg$\cdot$yr) around Q$_{\beta\beta}$. This work confirms the feasibility of IC detectors for the next-generation experiment LEGEND., Comment: 13 pages, 12 figures, submitted to EPJC
Published: 2021
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17. Calibration of the GERDA experiment

Author: GERDA collaboration, Agostini, M., Araujo, G. R., Bakalyarov, A. M., Balata, M., Barabanov, I., Baudis, L., Bauer, C., Bellotti, E., Belogurov, S., Bettini, A., Bezrukov, L., Biancacci, V., Bossio, E., Bothe, V., Brudanin, V., Brugnera, R., Caldwell, A., Cattadori, C., Chernogorov, A., Comellato, T., D'Andrea, V., Demidova, E. V., Di Marco, N., Doroshkevich, E., Fischer, F., Fomina, M., Gangapshev, A., Garfagnini, A., Gooch, C., Grabmayr, P., Gurentsov, V., Gusev, K., Hakenmüller, J., Hemmer, S., Hiller, R., Hofmann, W., Huang, J., Hult, M., Inzhechik, L. V., Csáthy, J. Janicskó, Jochum, J., Junker, M., Kazalov, V., Kermaïdic, Y., Khushbakht, H., Kihm, T., Kirpichnikov, I. V., Klimenko, A., Kneißl, R., Knöpfle, K. T., Kochetov, O., Kornoukhov, V. N., Krause, P., Kuzminov, V. V., Laubenstein, M., Lindner, M., Lippi, I., Lubashevskiy, A., Lubsandorzhiev, B., Lutter, G., Macolino, C., Majorovits, B., Maneschg, W., Manzanillas, L., Miloradovic, M., Mingazheva, R., Misiaszek, M., Moseev, P., Müller, Y., Nemchenok, I., Pandola, L., Pelczar, K., Pertoldi, L., Piseri, P., Pullia, A., Ransom, C., Rauscher, L., Riboldi, S., Rumyantseva, N., Sada, C., Salamida, F., Schönert, S., Schreiner, J., Schütt, M., Schütz, A. -K., Schulz, O., Schwarz, M., Schwingenheuer, B., Selivanenko, O., Shevchik, E., Shirchenko, M., Shtembari, L., Simgen, H., Smolnikov, A., Stukov, D., Vasenko, A. A., Veresnikova, A., Vignoli, C., von Sturm, K., Wester, T., Wiesinger, C., Wojcik, M., Yanovich, E., Zatschler, B., Zhitnikov, I., Zhukov, S. V., Zinatulina, D., Zschocke, A., Zsigmond, A. J., Zuber, K., and Zuzel, G.
Subjects: Physics - Instrumentation and Detectors, Nuclear Experiment
Abstract: The GERmanium Detector Array (GERDA) collaboration searched for neutrinoless double-$\beta$ decay in $^{76}$Ge with an array of about 40 high-purity isotopically-enriched germanium detectors. The experimental signature of the decay is a monoenergetic signal at Q$_{\beta\beta}$ = 2039.061(7)keV in the measured summed energy spectrum of the two emitted electrons. Both the energy reconstruction and resolution of the germanium detectors are crucial to separate a potential signal from various backgrounds, such as neutrino-accompanied double-$\beta$ decays allowed by the Standard Model. The energy resolution and stability were determined and monitored as a function of time using data from regular $^{228}$Th calibrations. In this work, we describe the calibration process and associated data analysis of the full GERDA dataset, tailored to preserve the excellent resolution of the individual germanium detectors when combining data over several years., Comment: 12 pages, 7 figures
Published: 2021
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18. Final Results of GERDA on the Search for Neutrinoless Double-$\beta$ Decay

Author: GERDA collaboration, Agostini, M., Araujo, G. R., Bakalyarov, A. M., Balata, M., Barabanov, I., Baudis, L., Bauer, C., Bellotti, E., Belogurov, S., Bettini, A., Bezrukov, L., Biancacci, V., Borowicz, D., Bossio, E., Bothe, V., Brudanin, V., Brugnera, R., Caldwell, A., Cattadori, C., Chernogorov, A., Comellato, T., D'Andrea, V., Demidova, E. V., Di Marco, N., Doroshkevich, E., Fischer, F., Fomina, M., Gangapshev, A., Garfagnini, A., Gooch, C., Grabmayr, P., Gurentsov, V., Gusev, K., Hakenmüller, J., Hemmer, S., Hiller, R., Hofmann, W., Huang, J., Hult, M., Inzhechik, L. V., Csáthy, J. Janicskó, Jochum, J., Junker, M., Kazalov, V., Kermaïdic, Y., Khushbakht, H., Kihm, T., Kirpichnikov, I. V., Klimenko, A., Kneißl, R., Knöpfle, K. T., Kochetov, O., Kornoukhov, V. N., Krause, P., Kuzminov, V. V., Laubenstein, M., Lazzaro, A., Lindner, M., Lippi, I., Lubashevskiy, A., Lubsandorzhiev, B., Lutter, G., Macolino, C., Majorovits, B., Maneschg, W., Manzanillas, L., Miloradovic, M., Mingazheva, R., Misiaszek, M., Moseev, P., Müller, Y., Nemchenok, I., Panas, K., Pandola, L., Pelczar, K., Pertoldi, L., Piseri, P., Pullia, A., Ransom, C., Rauscher, L., Riboldi, S., Rumyantseva, N., Sada, C., Salamida, F., Schönert, S., Schreiner, J., Schütt, M., Schütz, A. -K., Schulz, O., Schwarz, M., Schwingenheuer, B., Selivanenko, O., Shevchik, E., Shirchenko, M., Shtembari, L., Simgen, H., Smolnikov, A., Stukov, D., Vasenko, A. A., Veresnikova, A., Vignoli, C., von Sturm, K., Wester, T., Wiesinger, C., Wojcik, M., Yanovich, E., Zatschler, B., Zhitnikov, I., Zhukov, S. V., Zinatulina, D., Zschocke, A., Zsigmond, A. J., Zuber, K., and Zuzel, G.
Subjects: Nuclear Experiment, High Energy Physics - Experiment, Physics - Instrumentation and Detectors
Abstract: The GERmanium Detector Array (GERDA) experiment searched for the lepton-number-violating neutrinoless double-$\beta$ ($0\nu\beta\beta$) decay of $^{76}$Ge, whose discovery would have far-reaching implications in cosmology and particle physics. By operating bare germanium diodes, enriched in $^{76}$Ge, in an active liquid argon shield, GERDA achieved an unprecedently low background index of $5.2\times10^{-4}$ counts/(keV$\cdot$kg$\cdot$yr) in the signal region and met the design goal to collect an exposure of 100 kg$\cdot$yr in a background-free regime. When combined with the result of Phase I, no signal is observed after 127.2 kg$\cdot$yr of total exposure. A limit on the half-life of $0\nu\beta\beta$ decay in $^{76}$Ge is set at $T_{1/2}>1.8\times10^{26}$ yr at 90% C.L., which coincides with the sensitivity assuming no signal., Comment: 7 pages, 3 figures, submitted to Physical Review Letters
Published: 2020
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19. The first search for bosonic super-WIMPs with masses up to 1 MeV/c$^2$ with GERDA

Author: GERDA collaboration, Agostini, M., Bakalyarov, A. M., Balata, M., Barabanov, I., Baudis, L., Bauer, C., Bellotti, E., Belogurov, S., Bettini, A., Bezrukov, L., Borowicz, D., Bossio, E., Bothe, V., Brudanin, V., Brugnera, R., Caldwell, A., Cattadori, C., Chernogorov, A., Comellato, T., D'Andrea, V., Demidova, E. V., Di Marco, N., Doroshkevich, E., Egorov, V., Fischer, F., Fomina, M., Gangapshev, A., Garfagnini, A., Gooch, C., Grabmayr, P., Gurentsov, V., Gusev, K., Hakenmüller, J., Hemmer, S., Hiller, R., Hofmann, W., Hult, M., Inzhechik, L. V., Csáthy, J. Janicskó, Jochum, J., Junker, M., Kazalov, V., Kermaïdic, Y., Khushbakht, H., Kihm, T., Kirpichnikov, I. V., Klimenko, A., Kneißl, R., Knöpfle, K. T., Kochetov, O., Kornoukhov, V. N., Krause, P., Kuzminov, V. V., Laubenstein, M., Lazzaro, A., Lindner, M., Lippi, I., Lubashevskiy, A., Lubsandorzhiev, B., Lutter, G., Macolino, C., Majorovits, B., Maneschg, W., Miloradovic, M., Mingazheva, R., Misiaszek, M., Moseev, P., Nemchenok, I., Panas, K., Pandola, L., Pelczar, K., Pertoldi, L., Piseri, P., Pullia, A., Ransom, C., Rauscher, L., Riboldi, S., Rumyantseva, N., Sada, C., Salamida, F., Schönert, S., Schreiner, J., Schütt, M., Schütz, A-K., Schulz, O., Schwarz, M., Schwingenheuer, B., Selivanenko, O., Shevchik, E., Shirchenko, M., Simgen, H., Smolnikov, A., Stukov, D., Vasenko, A. A., Veresnikova, A., Vignoli, C., von Sturm, K., Wester, T., Wiesinger, C., Wojcik, M., Yanovich, E., Zatschler, B., Zhitnikov, I., Zhukov, S. V., Zinatulina, D., Zschocke, A., Zsigmond, A. J., and Zuzel, K. Zuber G.
Subjects: High Energy Physics - Experiment, Nuclear Experiment
Abstract: We present the first search for bosonic 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 $^{76}$Ge in an ultra-low 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 axion-like particles and dark photons to electrons of $g_{ae} < 3 \cdot 10^{-12}$ and ${\alpha'}/{\alpha} < 6.5 \cdot 10^{-24}$ at 90% credible interval, respectively, were obtained., Comment: 6 pages, 3 figures, submitted to Physical Review Letters, added list of authors, updated ref. [21]
Published: 2020
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20. Probing Majorana neutrinos with double-$\beta$ decay

Author: GERDA collaboration, Agostini, M., Bakalyarov, A. M., Balata, M., Barabanov, I., Baudis, L., Bauer, C., Bellotti, E., Belogurov, S., Bettini, A., Bezrukov, L., Borowicz, D., Brudanin, V., Brugnera, R., Caldwell, A., Cattadori, C., Chernogorov, A., Comellato, T., D'Andrea, V., Demidova, E. V., Di Marco, N., Domula, A., Doroshkevich, E., Egorov, V., Falkenstein, R., Fomina, M., Gangapshev, A., Garfagnini, A., Giordano, M., Grabmayr, P., Gurentsov, V., Gusev, K., Hakenmüller, J., Hegai, A., Heisel, M., Hemmer, S., Hiller, R., Hofmann, W., Hult, M., Inzhechik, L. V., Csáthy, J. Janicskó, Jochum, J., Junker, M., Kazalov, V., Kermaïdic, Y., Kihm, T., Kirpichnikov, I. V., Kirsch, A., Kish, A., Klimenko, A., Kneißl, R., Knöpfle, K. T., Kochetov, O., Kornoukhov, V. N., Krause, P., Kuzminov, V. V., Laubenstein, M., Lazzaro, A., Lindner, M., Lippi, I., Lubashevskiy, A., Lubsandorzhiev, B., Lutter, G., Macolino, C., Majorovits, B., Maneschg, W., Miloradovic, M., Mingazheva, R., Misiaszek, M., Moseev, P., Nemchenok, I., Panas, K., Pandola, L., Pelczar, K., Pertoldi, L., Piseri, P., Pullia, A., Ransom, C., Riboldi, S., Rumyantseva, N., Sada, C., Sala, E., Salamida, F., Schmitt, C., Schneider, B., Schönert, S., Schütz, A. -K., Schulz, O., Schwingenheuer, B., Schwarz, M., Selivanenko, O., Shevchik, E., Shirchenko, M., Simgen, H., Smolnikov, A., Stanco, L., Stukov, D., Vanhoefer, L., Vasenko, A. A., Veresnikova, A., von Sturm, K., Wagner, V., Wegmann, A., Wester, T., Wiesinger, C., Wojcik, M., Yanovich, E., Zhitnikov, I., Zhukov, S. V., Zinatulina, D., Zschocke, A., Zsigmond, A. J., Zuber, K., and Zuzel, G.
Subjects: High Energy Physics - Experiment, Nuclear Experiment
Abstract: A discovery that neutrinos are not the usual Dirac but Majorana fermions, i.e. identical to their antiparticles, would be a manifestation of new physics with profound implications for particle physics and cosmology. Majorana neutrinos would generate neutrinoless double-$\beta$ ($0\nu\beta\beta$) decay, a matter-creating process without the balancing emission of antimatter. So far, 0$\nu\beta\beta$ decay has eluded detection. The GERDA collaboration searches for the $0\nu\beta\beta$ decay of $^{76}$Ge by operating bare germanium detectors in an active liquid argon shield. With a total exposure of 82.4 kg$\cdot$yr, we observe no signal and derive a lower half-life limit of T$_{1/2}$ > 0.9$\cdot$10$^{26}$ yr (90% C.L.). Our T$_{1/2}$ sensitivity assuming no signal is 1.1$\cdot$10$^{26}$ yr. Combining the latter with those from other $0{\nu}\beta\beta$ decay searches yields a sensitivity to the effective Majorana neutrino mass of 0.07 - 0.16 eV, with corresponding sensitivities to the absolute mass scale in $\beta$ decay of 0.15 - 0.44 eV, and to the cosmological relevant sum of neutrino masses of 0.46 - 1.3 eV., Comment: Authors' main+supplementary text: 13+28 pages, 3+12 figures, 1+7 tables. Definite version to be published in Science
Published: 2019
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21. Modeling of GERDA Phase II data

Author: GERDA collaboration, Agostini, Matteo, Bakalyarov, Alexander M., Balata, Marco, Barabanov, Igor, Baudis, Laura, Bauer, Christian, Bellotti, Enrico, Belogurov, Sergej, Bettini, Alessandro, Bezrukov, Leonid, Borowicz, Dariusz, Bossio, Elisabetta, Bothe, Vikas, Brudanin, Victor, Brugnera, Riccardo, Caldwell, Allen, Cattadori, Carla, Chernogorov, Andrey, Comellato, Tommaso, D'Andrea, Valerio, Demidova, Elena V., Di Marco, Natalia, Domula, Alexander, Doroshkevich, Evgenyi, Egorov, Viacheslav, Fischer, Felix, Fomina, Maria, Gangapshev, Albert, Garfagnini, Alberto, Gooch, Chris, Grabmayr, Peter, Gurentsov, Valery, Gusev, Konstantin, Hakenmüller, Janina, Hemmer, Sabine, Hiller, Roman, Hofmann, Werner, Hult, Mikael, Inzhechik, Lev V., Csáthy, Jozsef Janicskó, Jochum, Josef, Junker, Matthias, Kazalov, Vladimir, Kermaïdic, Yoann, Kihm, Thomas, Kirpichnikov, Igor V., Klimenko, Alexander, Kneißl, Raphael, Knöpfle, Karl T., Kochetov, Oleg, Kornoukhov, Vasily N., Krause, Patrick, Kuzminov, Valery V., Laubenstein, Matthias, Lazzaro, Andrea, Lindner, Manfred, Lippi, Ivano, Lubashevskiy, Alexey, Lubsandorzhiev, Bayarto, Lutter, Guillaume, Macolino, Carla, Majorovits, Bela, Maneschg, Werner, Miloradovic, Michael, Mingazheva, Rizalina, Misiaszek, Marcin, Moseev, Pavel, Nemchenok, Igor, Panas, Krysztof, Pandola, Luciano, Pelczar, Krysztof, Pertoldi, Luigi, Piseri, Paolo, Pullia, Alberto, Ransom, Chloe, Riboldi, Stefano, Rumyantseva, Nadezda, Sada, Cinzia, Salamida, Francesco, Schönert, Stefan, Schreiner, Jochen, Schütt, Mario, Schütz, Ann-Katrin, Schulz, Oliver, Schwarz, Mario, Schwingenheuer, Bernhard, Selivanenko, Oleg, Shevchik, Egor, Shirchenko, Mark, Simgen, Hardy, Smolnikov, Anatoly, Stukov, Danila, Vanhoefer, Laura, Vasenko, Andrey A., Veresnikova, Anna, Vignoli, Chiara, von Sturm, Katharina, Wester, Thomas, Wiesinger, Christoph, Wojcik, Marcin, Yanovich, Evgeny, Zatschler, Birgit, Zhitnikov, Igor, Zhukov, Sergey V., Zinatulina, Daniya, Zschocke, Andreas, Zsigmond, Anna J., Zuber, Kai, and Zuzel, Grzegorz
Subjects: Nuclear Experiment, Physics - Instrumentation and Detectors
Abstract: The GERmanium Detector Array (GERDA) experiment at the Gran Sasso underground laboratory (LNGS) of INFN is searching for neutrinoless double-beta ($0\nu\beta\beta$) decay of $^{76}$Ge. 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$\cdot$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 $Q_{\beta\beta}$ for the $0\nu\beta\beta$ search, to extract a precise measurement of the half-life of the double-beta decay mode with neutrinos ($2\nu\beta\beta$) 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 $16.04^{+0.78}_{-0.85} \cdot 10^{-3}\,$cts/(kg$\cdot$keV$\cdot$yr) for the enriched BEGe data set and $14.68^{+0.47}_{-0.52} \cdot 10^{-3}\,$cts/(kg$\cdot$keV$\cdot$yr) for the enriched coaxial data set. These values are similar to the one of Gerda Phase I despite a much larger number of detectors and hence radioactive hardware components.
Published: 2019
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22. Characterization of 30 $^{76}$Ge enriched Broad Energy Ge detectors for GERDA Phase II

Author: GERDA collaboration, Agostini, M., Bakalyarov, A. M., Andreotti, E., Balata, M., Barabanov, I., Baudis, L., Barros, N., Bauer, C., Bellotti, E., Belogurov, S., Benato, G., Bettini, A., Bezrukov, L., Bode, T., Borowicz, D., Brudanin, V., Brugnera, R., Budjáš, D., Caldwell, A., Cattadori, C., Chernogorov, A., D'Andrea, V., Demidova, E. V., Di Marco, N., Domula, A., Doroshkevich, E., Egorov, V., Falkenstein, R., Freund, K., Gangapshev, A., Garfagnini, A., Gooch, C., Grabmayr, P., Gurentsov, V., Gusev, K., Hakenmüller, J., Hegai, A., Heisel, M., Hemmer, S., Hiller, R., Hofmann, W., Hult, M., Inzhechik, L. V., Csáthy, J. Janicskó, Jochum, J., Junker, M., Kazalov, V., Kermaidic, Y., Kihm, T., Kirpichnikov, I. V., Kirsch, A., Kish, A., Klimenko, A., Kneißl, R., Knöpfle, K. T., Kochetov, O., Kornoukhov, V. N., Kuzminov, V. V., Laubenstein, M., Lazzaro, A., Lehnert, B., Liao, Y., Lindner, M., Lippi, I., Lubashevskiy, A., Lubsandorzhiev, B., Lutter, G., Macolino, C., Majorovits, B., Maneschg, W., Miloradovic, M., Mingazheva, R., Misiaszek, M., Moseev, P., Nemchenok, I., Panas, K., Pandola, L., Pelczar, K., Pullia, A., Ransom, C., Riboldi, S., Rumyantseva, N., Sada, C., Salamida, F., Salathe, M., Schmitt, C., Schneider, B., Schönert, S., Schütz, A-K., Schulz, O., Schwingenheuer, B., Selivanenko, O., Shevchik, E., Shirchenko, M., Simgen, H., Smolnikov, A., Stanco, L., Ur, C. A., Vanhoefer, L., Vasenko, A. A., Veresnikova, A., von Sturm, K., Wagner, V., Wegmann, A., Wester, T., Wiesinger, C., Wojcik, M., Yanovich, E., Zhitnikov, I., Zhukov, S. V., Zinatulina, D., Zsigmond, A. J., Zuber, K., and Zuzel, G.
Subjects: Physics - Instrumentation and Detectors
Abstract: 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 $^{76}$Ge into $^{76}$Se+2e$^-$. GERDA has been conceived in two phases. Phase II, which started in December 2015, features several novelties including 30 new Ge 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 strength of pulse shape simulation codes., Comment: 29 pages, 18 figures
Published: 2019
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23. Searching for neutrinoless double beta decay with GERDA

Author: GERDA Collaboration, Agostini, M., Bakalyarov, A. M., Balata, M., Barabanov, I., Baudis, L., Bauer, C., Bellotti, E., Belogurov, S., Bettini, A., Bezrukov, L., Bode, T., Brudanin, V., Brugnera, R., Caldwell, A., Cattadori, C., Chernogorov, A., D'Andrea, V., Demidova, E. V., Di Marco, N., Domula, A., Doroshkevich, E., Egorov, V., Falkenstein, R., Gangapshev, A., Garfagnini, A., Gooch, C., Grabmayr, P., Gurentsov, V., Gusev, K., Hakenmüller, J., Hegai, A., Heisel, M., Hemmer, S., Hiller, R., Hofmann, W., Hult, M., Inzhechik, L. V., Csáthy, J. Janicskó, Jochum, J., Junker, M., Kazalov, V., Kermaidic, Y., Kihm, T., Kirpichnikov, I. V., Kirsch, A., Kish, A., Klimenko, A., Kneißl, R., Knöpfle, K. T., Kochetov, O., Kornoukhov, V. N., Kuzminov, V. V., Laubenstein, M., Lazzaro, A., Lebedev, V. I., Lindner, M., Lippi, I., Lubashevskiy, A., Lubsandorzhiev, B., Lutter, G., Macolino, C., Majorovits, B., Maneschg, W., Miloradovic, M., Mingazheva, R., Misiaszek, M., Moseev, P., Nemchenok, I., Panas, K., Pandola, L., Pullia, A., Ransom, C., Riboldi, S., Rumyantseva, N., Sada, C., Salamida, F., Schmitt, C., Schneider, B., Schreiner, J., Schulz, O., Schwingenheuer, B., Schönert, S., Schütz, A-K., Selivanenko, O., Shevchik, E., Shirchenko, M., Simgen, H., Smolnikov, A., Stanco, L., Vanhoefer, L., Vasenko, A. A., Veresnikova, A., von Sturm, K., Wagner, V., Wegmann, A., Wester, T., Wiesinger, C., Wojcik, M., Yanovich, E., Zhitnikov, I., Zhukov, S. V., Zinatulina, D., Zsigmond, A. J., Zuber, K., and Zuzel, G.
Subjects: Nuclear Experiment, Physics - Instrumentation and Detectors
Abstract: The GERmanium Detector Array (GERDA) experiment located at the INFN Gran Sasso Laboratory (Italy), is looking for the neutrinoless double beta decay of Ge76, by using high-purity germanium detectors made from isotopically enriched material. The combination of the novel experimental design, the careful material selection for radio-purity and the active/passive shielding techniques result in a very low residual background at the Q-value of the decay, about 1e-3 counts/(keV kg yr). This makes GERDA the first experiment in the field to be background-free for the complete design exposure of 100 kg yr. A search for neutrinoless double beta decay was performed with a total exposure of 47.7 kg yr: 23.2 kg yr come from the second phase (Phase II) of the experiment, in which the background is reduced by about a factor of ten with respect to the previous phase. The analysis presented in this paper includes 12.4 kg yr of new Phase II data. No evidence for a possible signal is found: the lower limit for the half-life of Ge76 is 8.0e25 yr at 90% CL. The experimental median sensitivity is 5.8e25 yr. The experiment is currently taking data. As it is running in a background-free regime, its sensitivity grows linearly with exposure and it is expected to surpass 1e26 yr within 2018., Comment: 8 pages, to appear in the proceedings of TAUP2017
Published: 2017

24. Limits on uranium and thorium bulk content in GERDA Phase I detectors

Author: GERDA collaboration, Agostini, M., Allardt, M., Bakalyarov, A. M., Balata, M., Barabanov, I., Baudis, L., Bauer, C., Becerici-Schmidt, N., Bellotti, E., Belogurov, S., Belyaev, S. T., Benato, G., Bettini, A., Bezrukov, L., Bode, T., Borowicz, D., Brudanin, V., Brugnera, R., Caldwell, A., Cattadori, C., Chernogorov, A., D'Andrea, V., Demidova, E. V., di Vacri, A., Domula, A., Doroshkevich, E., Egorov, V., Falkenstein, R., Fedorova, O., Freund, K., Frodyma, N., Gangapshev, A., Garfagnini, A., Grabmayr, P., Gurentsov, V., Gusev, K., Hakemüller, J., Hegai, A., Heisel, M., Hemmer, S., Hofmann, W., Hult, M., Inzhechik, L. V., Csathy, J. Janicsko, Jochum, J., Junker, M., Kazalov, V., Kihm, T., Kirpichnikov, I. V., Kirsch, A., Kish, A., Klimenko, A., Kneißl, R., Knöpfle, K. T., Kochetov, O., Kornoukhov, V. N., Kuzminov, V. V., Laubenstein, M., Lazzaro, A., Lebedev, V. I., Lehnert, B., Liao, H. Y., Lindner, M., Lippi, I., Lubashevskiy, A., Lubsandorzhiev, B., Lutter, G., Macolino, C., Majorovits, B., Maneschg, W., Medinaceli, E., Mingazheva, R., Misiaszek, M., Moseev, P., Nemchenok, I., Palioselitis, D., Panas, K., Pandola, L., Pelczar, K., Pullia, A., Riboldi, S., Rumyantseva, N., Sada, C., Salamida, F., Salathe, M., Schmitt, C., Schneider, B., Schönert, S., Schreiner, J., Schütz, A. -K., Schulz, O., Schwingenheuer, B., Selivanenko, O., Shevchik, E., Shirchenko, M., Simgen, H., Smolnikov, A., Stanco, L., Stepaniuk, M., Vanhoefer, L., Vasenko, A. A., Veresnikova, A., von Sturm, K., Wagner, V., Walter, M., Wegmann, A., Wester, T., Wiesinger, C., Wojcik, M., Yanovich, E., Zhitnikov, I., Zhukov, S. V., Zinatulina, D., Zuber, K., and Zuzel, G.
Subjects: Physics - Instrumentation and Detectors, Nuclear Experiment
Abstract: Internal contaminations of $^{238}$U, $^{235}$U and $^{232}$Th in the bulk of high purity germanium detectors are potential backgrounds for experiments searching for neutrinoless double beta decay of $^{76}$Ge. The data from GERDA Phase~I have been analyzed for alpha events from the decay chain of these contaminations by looking for full decay chains and for time correlations between successive decays in the same detector. No candidate events for a full chain have been found. Upper limits on the activities in the range of a few nBq/kg for $^{226}$Ra, $^{227}$Ac and $^{228}$Th, the long-lived daughter nuclides of $^{238}$U, $^{235}$U and $^{232}$Th, respectively, have been derived. With these upper limits a background index in the energy region of interest from $^{226}$Ra and $^{228}$Th contamination is estimated which satisfies the prerequisites of a future ton scale germanium double beta decay experiment., Comment: 2 figures, 7 pages
Published: 2016
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25. Background-free search for neutrinoless double-β decay of 76Ge with GERDA.

Author: GERDA Collaboration
Subjects: GERDA Collaboration, nucl-ex, hep-ex, physics.ins-det, General Science & Technology
Abstract: Many extensions of the Standard Model of particle physics explain the dominance of matter over antimatter in our Universe by neutrinos being their own antiparticles. This would imply the existence of neutrinoless double-β decay, which is an extremely rare lepton-number-violating radioactive decay process whose detection requires the utmost background suppression. Among the programmes that aim to detect this decay, the GERDA Collaboration is searching for neutrinoless double-β decay of 76Ge by operating bare detectors, made of germanium with an enriched 76Ge fraction, in liquid argon. After having completed Phase I of data taking, we have recently launched Phase II. Here we report that in GERDA Phase II we have achieved a background level of approximately 10-3 counts keV-1 kg-1 yr-1. This implies that the experiment is background-free, even when increasing the exposure up to design level. This is achieved by use of an active veto system, superior germanium detector energy resolution and improved background recognition of our new detectors. No signal of neutrinoless double-β decay was found when Phase I and Phase II data were combined, and we deduce a lower-limit half-life of 5.3 × 1025 years at the 90 per cent confidence level. Our half-life sensitivity of 4.0 × 1025 years is competitive with the best experiments that use a substantially larger isotope mass. The potential of an essentially background-free search for neutrinoless double-β decay will facilitate a larger germanium experiment with sensitivity levels that will bring us closer to clarifying whether neutrinos are their own antiparticles.
Published: 2017

26. Results on ββ decay with emission of two neutrinos or Majorons in 76Ge from GERDA Phase I: GERDA Collaboration

Author: GERDA Collaboration, Agostini, M, Allardt, M, Bakalyarov, AM, Balata, M, Barabanov, I, Barros, N, Baudis, L, Bauer, C, Becerici-Schmidt, N, Bellotti, E, Belogurov, S, Belyaev, ST, Benato, G, Bettini, A, Bezrukov, L, Bode, T, Borowicz, D, Brudanin, V, Brugnera, R, Budjáš, D, Caldwell, A, Cattadori, C, Chernogorov, A, D’Andrea, V, Demidova, EV, di Vacri, A, Domula, A, Doroshkevich, E, Egorov, V, Falkenstein, R, Fedorova, O, Freund, K, Frodyma, N, Gangapshev, A, Garfagnini, A, Grabmayr, P, Gurentsov, V, Gusev, K, Hegai, A, Heisel, M, Hemmer, S, Heusser, G, Hofmann, W, Hult, M, Inzhechik, LV, Csáthy, JJ, Jochum, J, Junker, M, Kazalov, V, Kihm, T, Kirpichnikov, IV, Kirsch, A, Klimenko, A, Knöpfle, KT, Kochetov, O, Kornoukhov, VN, Kuzminov, VV, Laubenstein, M, Lazzaro, A, Lebedev, VI, Lehnert, B, Liao, HY, Lindner, M, Lippi, I, Lubashevskiy, A, Lubsandorzhiev, B, Lutter, G, Macolino, C, Majorovits, B, Maneschg, W, Medinaceli, E, Misiaszek, M, Moseev, P, Nemchenok, I, Palioselitis, D, Panas, K, Pandola, L, Pelczar, K, Pullia, A, Riboldi, S, Rumyantseva, N, Sada, C, Salathe, M, Schmitt, C, Schneider, B, Schönert, S, Schreiner, J, Schütz, AK, Schulz, O, Schwingenheuer, B, Selivanenko, O, Shirchenko, M, Simgen, H, Smolnikov, A, Stanco, L, Stepaniuk, M, Ur, CA, Vanhoefer, L, and Vasenko, AA
Subjects: nucl-ex, physics.ins-det, Nuclear & Particles Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics
Abstract: A search for neutrinoless ββ decay processes accompanied with Majoron emission has been performed using data collected during Phase I of the GERmanium Detector Array (GERDA) experiment at the Laboratori Nazionali del Gran Sasso of INFN (Italy). Processes with spectral indices n = 1, 2, 3, 7 were searched for. No signals were found and lower limits of the order of 1023 yr on their half-lives were derived, yielding substantially improved results compared to previous experiments with 76Ge. A new result for the half-life of the neutrino-accompanied ββ decay of 76Ge with significantly reduced uncertainties is also given, resulting in (Formula presented.) yr.
Published: 2015

27. Improvement of the energy resolution via an optimized digital signal processing in GERDA Phase I

Author: GERDA Collaboration, Agostini, M, Allardt, M, Bakalyarov, AM, Balata, M, Barabanov, I, Barros, N, Baudis, L, Bauer, C, Becerici-Schmidt, N, Bellotti, E, Belogurov, S, Belyaev, ST, Benato, G, Bettini, A, Bezrukov, L, Bode, T, Borowicz, D, Brudanin, V, Brugnera, R, Budjáš, D, Caldwell, A, Cattadori, C, Chernogorov, A, D’Andrea, V, Demidova, EV, Vacri, AD, Domula, A, Doroshkevich, E, Egorov, V, Falkenstein, R, Fedorova, O, Freund, K, Frodyma, N, Gangapshev, A, Garfagnini, A, Grabmayr, P, Gurentsov, V, Gusev, K, Hegai, A, Heisel, M, Hemmer, S, Heusser, G, Hofmann, W, Hult, M, Inzhechik, LV, Janicskó Csáthy, J, Jochum, J, Junker, M, Kazalov, V, Kihm, T, Kirpichnikov, IV, Kirsch, A, Klimenko, A, Knöpfle, KT, Kochetov, O, Kornoukhov, VN, Kuzminov, VV, Laubenstein, M, Lazzaro, A, Lebedev, VI, Lehnert, B, Liao, HY, Lindner, M, Lippi, I, Lubashevskiy, A, Lubsandorzhiev, B, Lutter, G, Macolino, C, Majorovits, B, Maneschg, W, Medinaceli, E, Misiaszek, M, Moseev, P, Nemchenok, I, Palioselitis, D, Panas, K, Pandola, L, Pelczar, K, Pullia, A, Riboldi, S, Rumyantseva, N, Sada, C, Salathe, M, Schmitt, C, Schneider, B, Schönert, S, Schreiner, J, Schütz, AK, Schulz, O, Schwingenheuer, B, Selivanenko, O, Shirchenko, M, Simgen, H, Smolnikov, A, Stanco, L, Stepaniuk, M, Ur, CA, Vanhoefer, L, and Vasenko, AA
Subjects: physics.ins-det, nucl-ex, Nuclear & Particles Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics
Abstract: An optimized digital shaping filter has been developed for the Gerda experiment which searches for neutrinoless double beta decay in $$^{76}$$76Ge. The Gerda Phase I energy calibration data have been reprocessed and an average improvement of 0.3 keV in energy resolution (FWHM) corresponding to 10 % at the $$Q$$Q value for $$0\nu \beta \beta $$0νββ decay in $$^{76}$$76Ge is obtained. This is possible thanks to the enhanced low-frequency noise rejection of this Zero Area Cusp (ZAC) signal shaping filter.
Published: 2015

28. The background in the neutrinoless double beta decay experiment GERDA

Author: The GERDA collaboration, Agostini, M., Allardt, M., Andreotti, E., Bakalyarov, A. M., Balata, M., Barabanov, I., Heider, M. Barnabe, Barros, N., Baudis, L., Bauer, C., Becerici-Schmidt, N., Bellotti, E., Belogurov, S., Belyaev, S. T., Benato, G., Bettini, A., Bezrukov, L., Bode, T., Brudanin, V., Brugnera, R., Budjas, D., Caldwell, A., Cattadori, C., Chernogorov, A., Cossavella, F., Demidova, E. V., Domula, A., Egorov, V., Falkenstein, R., Ferella, A., Freund, K., Frodyma, N., Gangapshev, A., Garfagnini, A., Gotti, C., Grabmayr, P., Gurentsov, V., Gusev, K., Guthikonda, K. K., Hampel, W., Hegai, A., Heisel, M., Hemmer, S., Heusser, G., Hofmann, W., Hult, M., Inzhechik, L. V., Ioannucci, L., Csathy, J. Janicsko, Jochum, J., Junker, M., Kihm, T., Kirpichnikov, I. V., Kirsch, A., Klimenko, A., Knoepfle, K. T., Kochetov, O., Kornoukhov, V. N., Kuzminov, V. V., Laubenstein, M., Lazzaro, A., Lebedev, V. I., Lehnert, B., Liao, H. Y., Lindner, M., Lippi, I., Liu, X., Lubashevskiy, A., Lubsandorzhiev, B., Lutter, G., Macolino, C., Machado, A. A., Majorovits, B., Maneschg, W., Nemchenok, I., Nisi, S., O'Shaughnessy, C., Palioselitis, D., Pandola, L., Pelczar, K., Pessina, G., Pullia, A., Riboldi, S., Sada, C., Salathe, M., Schmitt, C., Schreiner, J., Schulz, O., Schwingenheuer, B., Schoenert, S., Shevchik, E., Shirchenko, M., Simgen, H., Smolnikov, A., Stanco, L., Strecker, H., Tarka, M., Ur, C. A., Vasenko, A. A., Volynets, O., von Sturm, K., Wagner, V., Walter, M., Wegmann, A., Wester, T., Wojcik, M., Yanovich, E., Zavarise, P., Zhitnikov, I., Zhukov, S. V., Zinatulina, D., Zuber, K., and Zuzel, G.
Subjects: Physics - Instrumentation and Detectors, High Energy Physics - Experiment
Abstract: The GERmanium Detector Array (GERDA) experiment at the Gran Sasso underground laboratory (LNGS) of INFN is searching for neutrinoless double beta decay of 76Ge. The signature of the signal is a monoenergetic peak at 2039 keV, the Q-value of the decay, Q_bb. To avoid bias in the signal search, the present analysis does not consider all those events, that fall in a 40 keV wide region centered around Q_bb. The main parameters needed for the neutrinoless double beta decay analysis are described. A background model was developed to describe the observed energy spectrum. The model contains several contributions, that are expected on the basis of material screening or that are established by the observation of characteristic structures in the energy spectrum. The model predicts a flat energy spectrum for the blinding window around Q_bb with a background index ranging from 17.6 to 23.8*10^{-3} counts/(keV kg yr). A part of the data not considered before has been used to test if the predictions of the background model are consistent. The observed number of events in this energy region is consistent with the background model. The background at Q-bb is dominated by close sources, mainly due to 42K, 214Bi, 228Th, 60Co and alpha emitting isotopes from the 226Ra decay chain. The individual fractions depend on the assumed locations of the contaminants. It is shown, that after removal of the known gamma peaks, the energy spectrum can be fitted in an energy range of 200 kev around Q_bb with a constant background. This gives a background index consistent with the full model and uncertainties of the same size.
Published: 2013
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29. The GERDA experiment for the search of 0\nu\beta\beta\ decay in ^{76}Ge

Author: GERDA Collaboration, Ackermann, K. -H., Agostini, M., Allardt, M., Altmann, M., Andreotti, E., Bakalyarov, A. M., Balata, M., Barabanov, I., Heider, M. Barnabe, Barros, N., Baudis, L., Bauer, C., Becerici-Schmidt, N., Bellotti, E., Belogurov, S., Belyaev, S. T., Benato, G., Bettini, A., Bezrukov, L., Bode, T., Brudanin, V., Brugnera, R., Budjas, D., Caldwell, A., Cattadori, C., Chernogorov, A., Chkvorets, O., Cossavella, F., D`Andragora, A., Demidova, E. V., Denisov, A., di Vacri, A., Domula, A., Egorov, V., Falkenstein, R., Ferella, A., Freund, K., Froborg, F., Frodyma, N., Gangapshev, A., Garfagnini, A., Gasparro, J., Gazzana, S., de Orduna, R. Gonzalez, Grabmayr, P., Gurentsov, V., Gusev, K., Guthikonda, K. K., Hampel, W., Hegai, A., Heisel, M., Hemmer, S., Heusser, G., Hofmann, W., Hult, M., Inzhechik, L. V., Ioannucci, L., Csalty, J. Janicsko, Jochum, J., Junker, M., Kankanyan, R., Kianovsky, S., Kihm, T., Kiko, J., Kirpichnikov, I. V., Kirsch, A., Klimenko, A., Knapp, M., Knöpfle, K. T., Kochetov, O., Kornoukhov, V. N., Kröninger, K., Kusminov, V., Laubenstein, M., Lazzaro, A., Lebedev, V. I., Lehnert, B., Lenz, D., Liao, H., Lindner, M., Lippi, I., Liu, J., Liu, X., Lubashevskiy, A., Lubsandorzhiev, B., Machado, A. A., Majorovits, B., Maneschg, W., Marissens, G., Mayer, S., Meierhofer, G., Nemchenok, I., Niedermeier, L., Nisi, S., Oehm, J., O'Shaughnessy, C., Pandola, L., Peiffer, P., Pelczar, K., Pullia, A., Riboldi, S., Ritter, F., Alvarez, C. Rossi, Sada, C., Salathe, M., Schmitt, C., Schönert, S., Schreiner, J., Schubert, J., Schulz, O., Schwan, U., Schwingenheuer, B., Seitz, H., Shevchik, E., Shirchenko, M., Simgen, H., Smolnikov, A., Stanco, L., Stelzer, F., Strecker, H., Tarka, M., Trunk, U., Ur, C. A., Vasenko, A. A., Vogt, S., Volynets, O., von Sturm, K., Wagner, V., Walter, M., Wegmann, A., Wojcik, M., Yanovich, E., Zavarise, P., Zhitnikov, I., Zhukov, S. V., Zinatulina, D., Zuber, K., and Zuzel, G.
Subjects: Physics - Instrumentation and Detectors, High Energy Physics - Experiment, Nuclear Experiment
Abstract: The GERDA collaboration is performing a search for neutrinoless double beta decay of ^{76}Ge with the eponymous detector. The experiment has been installed and commissioned at the Laboratori Nazionali del Gran Sasso and has started operation in November 2011. The design, construction and first operational results are described, along with detailed information from the R&D phase., Comment: 31 pages, 23 figures, submitted to EPJC
Published: 2012
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30. Measurement of the half-life of the two-neutrino double beta decay of Ge-76 with the Gerda experiment

Author: GERDA Collaboration, Agostini, M., Allardt, M., Andreotti, E., Bakalyarov, A. M., Balata, M., Barabanov, I., Heider, M. Barnabe, Barros, N., Baudis, L., Bauer, C., Becerici-Schmidt, N., Bellotti, E., Belogurov, S., Belyaev, S. T., Benato, G., Bettini, A., Bezrukov, L., Bode, T., Brudanin, V., Brugnera, R., Budjas, D., Caldwell, A., Cattadori, C., Chernogorov, A., Cossavella, F., Demidova, E. V., Denisov, A., Domula, A., Egorov, V., Falkenstein, R., Ferella, A. D., Freund, K., Froborg, F., Frodyma, N., Gangapshev, A., Garfagnini, A., Gazzana, S., Grambayr, P., Gurentsov, V., Gusev, K., Guthikonda, K. K., Hampel, W., Hegai, A., Heisel, M., Hemmer, S., Heusser, G., Hofmann, W., Hult, M., Inzhechik, L. V., Ioannucci, L., Csathy, J. Janicsko, Jochum, J., Junker, M., Kianovsky, S., Kirpichnikov, I. V., Kirsch, A., Klimenko, A., Knoepfle, K. T., Kochetov, O., Kornoukhov, V. N., Kusminov, V., Laubenstein, M., Lazzaro, A., Lebedev, V. I., Lehnert, B., Liao, H. Y., Lindner, M., Lippi, I., Liu, X., Lubashevskiy, A., Lubsandorzhiev, B., Lutter, G., Machado, A. A., Majorovits, B., Maneschg, W., Nemchenok, I., Nisi, S., O'Shaughnessy, C., Pandola, L., Pelczar, K., Peraro, L., Pullia, A., Riboldi, S., Ritter, F., Sada, C., Salathe, M., Schmitt, C., Schoenert, S., Schreiner, J., Schulz, O., Schwingenheuer, B., Shevchik, E., Shirchenko, M., Simgen, H., Smolnikov, A., Stanco, L., Strecker, H., Tarka, M., Ur, C. A., Vasenko, A. A., Volynets, O., von Sturm, K., Walter, M., Wegmann, A., Wojcik, M., Yanovich, E., Zavarise, P., Zhitnikov, I., Zhukov, S. V., Zinatulina, D., Zuber, K., and Zuzel, G.
Subjects: Nuclear Experiment, High Energy Physics - Experiment
Abstract: The primary goal of the GERmanium Detector Array (Gerda) experiment at the Laboratori Nazionali del Gran Sasso of INFN is the search for the neutrinoless double beta decay of Ge-76. High-purity germanium detectors made from material enriched in Ge-76 are operated directly immersed in liquid argon, allowing for a substantial reduction of the background with respect to predecessor experiments. The first 5.04 kg yr of data collected in Phase I of the experiment have been analyzed to measure the half-life of the neutrino-accompanied double beta decay of Ge-76. The observed spectrum in the energy range between 600 and 1800 keV is dominated by the double beta decay of Ge-76. The half-life extracted from Gerda data is T(1/2) = (1.84 +0.14 -0.10) 10^{21} yr., Comment: 14 pages, 2 figures, submitted to J. Phys. G: Nucl. Part. Phys
Published: 2012
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31. Limit on the radiative neutrinoless double electron capture of 36 Ar from GERDA Phase I

Author: Agostini, M., Allardt, M., Bakalyarov, A. M., Balata, M., Barabanov, I., Barros, N., Baudis, L., Bauer, C., Bellotti, E., Belogurov, S., Belyaev, S. T., Benato, G., Bettini, A., Bezrukov, L., Bode, T., Borowicz, D., Brudanin, V., Brugnera, R., Caldwell, A., Cattadori, C., Chernogorov, A., D’Andrea, V., Demidova, E. V., di Vacri, A., Domula, A., Doroshkevich, E., Egorov, V., Falkenstein, R., Fedorova, O., Freund, K., Frodyma, N., Gangapshev, A., Garfagnini, A., Gooch, C., Grabmayr, P., Gurentsov, V., Gusev, K., Hakenmüller, J., Hegai, A., Heisel, M., Hemmer, S., Heusser, G., Hofmann, W., Hult, M., Inzhechik, L. V., Csáthy, J. Janicskó, Jochum, J., Junker, M., Kazalov, V., Kihm, T., Kirpichnikov, I. V., Kirsch, A., Kish, A., Klimenko, A., Kneißl, R., Knöpfle, K. T., Kochetov, O., Kornoukhov, V. N., Kuzminov, V. V., Laubenstein, M., Lazzaro, A., Lebedev, V. I., Lehnert, B., Liao, H. Y., Lindner, M., Lippi, I., Lubashevskiy, A., Lubsandorzhiev, B., Lutter, G., Macolino, C., Majorovits, B., Maneschg, W., Medinaceli, E., Miloradovic, M., Mingazheva, R., Misiaszek, M., Moseev, P., Nemchenok, I., Palioselitis, D., Panas, K., Pandola, L., Pelczar, K., Pullia, A., Riboldi, S., Rumyantseva, N., Sada, C., Salamida, F., Salathe, M., Schmitt, C., Schneider, B., Schönert, S., Schreiner, J., Schütz, A.-K., Schulz, O., Schwingenheuer, B., Selivanenko, O., Shirchenko, M., Simgen, H., Smolnikov, A., Stanco, L., Stepaniuk, M., Vanhoefer, L., Vasenko, A. A., Veresnikova, A., von Sturm, K., Wagner, V., Walter, M., Wegmann, A., Wester, T., Wiesinger, C., Wilsenach, H., Wojcik, M., Yanovich, E., Zhitnikov, I., Zhukov, S. V., Zinatulina, D., Zuber, K., Zuzel, G., and GERDA collaboration
Published: 2016
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32. Highlights from GERDA: Probing the Majorana Neutrino Mass at 100 meV

Author: Carla Maria Cattadori and on behalf of the GERDA Collaboration
Subjects: neutrino, majorana, GERDA, Double Beta Decay, germanium, Elementary particle physics, QC793-793.5
Abstract: Since 2010, the Gerda experiment at Laboratori Nazionali del Gran Sasso (LNGS) operates searching for neutrinoless double beta decay ( 0 ν β β ) of 76 Ge to the ground and excited states of 76 Se. 0 ν β β is an ultra-rare process whose detection would directly establish the Majorana nature of the neutrino and provide a direct measurement of its mass. Since the apparatus upgrade in 2013–2015, the collaboration released the third update of the achieved results at the Neutrino 2018 Conference. The hardware upgrade and the fine tuning of the powerful analysis tools to reconstruct the event energy and to discriminate the background allowed the achievement of the energy resolution of 3 keV and 3.6 keV for Broad Energy Germanium (BEGe) and Coaxial Germanium (Coax) detectors, respectively, and an unprecedented low background index of 0.6 · 10 - 3 cts/(keV·kg·yr) 10 - 3 cts/(keV·kg·yr) in a 230 keV netto range centered at Q β β in the exposure of 58.93 kg·yr. No evidence of the 0 ν β β decay is found at the Q β β = 2039.1 keV, and the limit of 0.9 · 10 26 yr on the half-life ( T 1 / 2 0 ν ) at 90% C.L. is set. This corresponds to the limit range for the effective Majorana neutrino mass m e e of 110–260 meV. The Gerda sensitivity in terms of background index, energy resolution and exposure is the best achieved so far in 76 Ge double beta decay experiments, the energy resolution and background in the Region Of Interest (ROI) allow Gerda to operate in a background-free regime and to set a world record.
Published: 2019
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33. Results on 76 Ge from GERDA Phase I: GERDA Collaboration

Author: Agostini, M., Allardt, M., Bakalyarov, A. M., Balata, M., Barabanov, I., Barros, N., Baudis, L., Bauer, C., Becerici-Schmidt, N., Bellotti, E., Belogurov, S., Belyaev, S. T., Benato, G., Bettini, A., Bezrukov, L., Bode, T., Borowicz, D., Brudanin, V., Brugnera, R., Budjáš, D., Caldwell, A., Cattadori, C., Chernogorov, A., D’Andrea, V., Demidova, E. V., di Vacri, A., Domula, A., Doroshkevich, E., Egorov, V., Falkenstein, R., Fedorova, O., Freund, K., Frodyma, N., Gangapshev, A., Garfagnini, A., Grabmayr, P., Gurentsov, V., Gusev, K., Hegai, A., Heisel, M., Hemmer, S., Heusser, G., Hofmann, W., Hult, M., Inzhechik, L. V., Csáthy, J. Janicskó, Jochum, J., Junker, M., Kazalov, V., Kihm, T., Kirpichnikov, I. V., Kirsch, A., Klimenko, A., Knöpfle, K. T., Kochetov, O., Kornoukhov, V. N., Kuzminov, V. V., Laubenstein, M., Lazzaro, A., Lebedev, V. I., Lehnert, B., Liao, H. Y., Lindner, M., Lippi, I., Lubashevskiy, A., Lubsandorzhiev, B., Lutter, G., Macolino, C., Majorovits, B., Maneschg, W., Medinaceli, E., Misiaszek, M., Moseev, P., Nemchenok, I., Palioselitis, D., Panas, K., Pandola, L., Pelczar, K., Pullia, A., Riboldi, S., Rumyantseva, N., Sada, C., Salathe, M., Schmitt, C., Schneider, B., Schönert, S., Schreiner, J., Schütz, A.-K., Schulz, O., Schwingenheuer, B., Selivanenko, O., Shirchenko, M., Simgen, H., Smolnikov, A., Stanco, L., Stepaniuk, M., Ur, C. A., Vanhoefer, L., Vasenko, A. A., Veresnikova, A., von Sturm, K., Wagner, V., Walter, M., Wegmann, A., Wester, T., Wilsenach, H., Wojcik, M., Yanovich, E., Zavarise, P., Zhitnikov, I., Zhukov, S. V., Zinatulina, D., Zuber, K., Zuzel, G., and GERDA Collaboration
Published: 2015
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34. Improvement of the energy resolution via an optimized digital signal processing in GERDA Phase I

Author: Agostini, M., Allardt, M., Bakalyarov, A. M., Balata, M., Barabanov, I., Barros, N., Baudis, L., Bauer, C., Becerici-Schmidt, N., Bellotti, E., Belogurov, S., Belyaev, S. T., Benato, G., Bettini, A., Bezrukov, L., Bode, T., Borowicz, D., Brudanin, V., Brugnera, R., Budjáš, D., Caldwell, A., Cattadori, C., Chernogorov, A., D’Andrea, V., Demidova, E. V., Vacri, A. di, Domula, A., Doroshkevich, E., Egorov, V., Falkenstein, R., Fedorova, O., Freund, K., Frodyma, N., Gangapshev, A., Garfagnini, A., Grabmayr, P., Gurentsov, V., Gusev, K., Hegai, A., Heisel, M., Hemmer, S., Heusser, G., Hofmann, W., Hult, M., Inzhechik, L. V., Janicskó Csáthy, J., Jochum, J., Junker, M., Kazalov, V., Kihm, T., Kirpichnikov, I. V., Kirsch, A., Klimenko, A., Knöpfle, K. T., Kochetov, O., Kornoukhov, V. N., Kuzminov, V. V., Laubenstein, ********************M., Lazzaro, A., Lebedev, V. I., Lehnert, B., Liao, H. Y., Lindner, M., Lippi, I., Lubashevskiy, A., Lubsandorzhiev, B., Lutter, G., Macolino, C., Majorovits, B., Maneschg, W., Medinaceli, E., Misiaszek, M., Moseev, P., Nemchenok, I., Palioselitis, D., Panas, K., Pandola, L., Pelczar, K., Pullia, A., Riboldi, S., Rumyantseva, N., Sada, C., Salathe, M., Schmitt, C., Schneider, B., Schönert, S., Schreiner, J., Schütz, A.-K., Schulz, O., Schwingenheuer, B., Selivanenko, O., Shirchenko, M., Simgen, H., Smolnikov, A., Stanco, L., Stepaniuk, M., Ur, C. A., Vanhoefer, L., Vasenko, A. A., Veresnikova, A., von Sturm, K., Wagner, V., Walter, M., Wegmann, A., Wester, T., Wilsenach, H., Wojcik, M., Yanovich, E., Zavarise, P., Zhitnikov, I., Zhukov, S. V., Zinatulina, D., Zuber, K., Zuzel, G., and GERDA Collaboration
Published: 2015
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35. Pulse shape analysis in Gerda Phase II

Author: The GERDA collaboration, Agostini, M., Araujo, G., Bakalyarov, A. M., Balata, M., Barabanov, I., Baudis, L., Bauer, C., Bellotti, E., Belogurov, S., Bettini, A., Bezrukov, L., Biancacci, V., Bossio, E., Bothe, V., Brudanin, V., Brugnera, R., Caldwell, A., Cattadori, C., Chernogorov, A., Comellato, T., D'Andrea, V., Demidova, E. V., Di Marco, N., Doroshkevich, E., Fischer, F., Fomina, M., Gangapshev, A., Garfagnini, A., Gooch, C., Grabmayr, P., Gurentsov, V., Gusev, K., Hakenmüller, J., Hemmer, S., Hiller, R., Hofmann, W., Huang, J., Hult, M., Inzhechik, L. V., Csáthy, J. Janicskó, Jochum, J., Junker, M., Kazalov, V., Kermaïdic, Y., Khushbakht, H., Kihm, T., Kilgus, K., Kirsch, A., Kirpichnikov, I. V., Klimenko, A., Knöpfle, K. T., Kochetov, O., Kornoukhov, V. N., Krause, P., Kuzminov, V. V., Laubenstein, M., Lazzaro, A., Lindner, M., Lippi, I., Lubashevskiy, A., Lubsandorzhiev, B., Lutter, G., Macolino, C., Majorovits, B., Maneschg, W., Manzanillas, L., Miloradovic, M., Mingazheva, R., Misiaszek, M., Müller, Y., Nemchenok, I., Panas, K., Pandola, L., Pelczar, K., Pertoldi, L., Piseri, P., Pullia, A., Ransom, C., Rauscher, L., Redchuk, M., Riboldi, S., Rumyantseva, N., Sada, C., Salamida, F., Schönert, S., Schreiner, J., Schütt, M., Schütz, A. -K., Schulz, O., Schwarz, M., Schwingenheuer, B., Selivanenko, O., Shevchik, E., Shirchenko, M., Shtembari, L., Simgen, H., Smolnikov, A., Stukov, D., Vasenko, A. A., Veresnikova, A., Vignoli, C., von Sturm, K., Wagner, V., Wester, T., Wiesinger, C., Wojcik, M., Yanovich, E., Zatschler, B., Zhitnikov, I., Zhukov, S. V., Zinatulina, D., Zschocke, A., Zsigmond, A. J., Zuber, K., and Zuzel, G.
Subjects: Technology, Physics - Instrumentation and Detectors, Physics and Astronomy (miscellaneous), FOS: Physical sciences, Instrumentation and Detectors (physics.ins-det), Nuclear Experiment (nucl-ex), Nuclear Experiment, Engineering (miscellaneous), ddc:600
Abstract: The GERmanium Detector Array (Gerda) collaboration searched for neutrinoless double-$$\beta $$ β decay in $$^{76}$$ 76 Ge using isotopically enriched high purity germanium detectors at the Laboratori Nazionali del Gran Sasso of INFN. After Phase I (2011–2013), the experiment benefited from several upgrades, including an additional active veto based on LAr instrumentation and a significant increase of mass by point-contact germanium detectors that improved the half-life sensitivity of Phase II (2015–2019) by an order of magnitude. At the core of the background mitigation strategy, the analysis of the time profile of individual pulses provides a powerful topological discrimination of signal-like and background-like events. Data from regular $$^{228}$$ 228 Th calibrations and physics data were both considered in the evaluation of the pulse shape discrimination performance. In this work, we describe the various methods applied to the data collected in Gerda Phase II corresponding to an exposure of 103.7 kg year. These methods suppress the background by a factor of about 5 in the region of interest around $$Q_{\beta \beta }= 2039$$ Q β β = 2039 keV, while preserving $$(81\pm 3)$$ ( 81 ± 3 ) % of the signal. In addition, an exhaustive list of parameters is provided which were used in the final data analysis.
Published: 2021

36. Characterization of inverted coaxial 76Ge detectors in GERDA for future double-β decay experiments

Author: GERDA Collaboration, Agostini, M, et al, Baudis, L, Araujo, G, Müller, Yannick, Bakalyarov, A M, and University of Zurich
Subjects: Physics and Astronomy (miscellaneous), 530 Physics, 10192 Physics Institute, 2201 Engineering (miscellaneous), 3101 Physics and Astronomy (miscellaneous), Engineering (miscellaneous)
Published: 2021
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37. First Search for Bosonic Superweakly Interacting Massive Particles with Masses up to 1 MeV/c2 with GERDA

Author: GERDA Collaboration, et al, Baudis, Laura, Hiller, Roman, Miloradovic, Michael, Mingazheva, Rizalina, Ransom, Chloe, and University of Zurich
Subjects: 530 Physics, General Physics and Astronomy, 10192 Physics Institute, 3100 General Physics and Astronomy
Published: 2020
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38. Modeling of GERDA Phase II data

Author: GERDA Collaboration, et al, Baudis, Laura, Hiller, Roman, Miloradovic, Michael, Mingazheva, Rizalina, Ransom, Chloe, and University of Zurich
Subjects: Nuclear and High Energy Physics, 530 Physics, 10192 Physics Institute, 3106 Nuclear and High Energy Physics
Published: 2020
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39. Probing Majorana neutrinos with double-β decay

Author: Baudis, Laura, Mingazheva, R, Hiller, Roman, Miloradovic, Michael, Kish, A, Ransom, Chloe, et al, GERDA Collaboration, and University of Zurich
Subjects: 1000 Multidisciplinary, Multidisciplinary, 530 Physics, 10192 Physics Institute
Published: 2019
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40. Modeling of GERDA Phase II data / Working Paper

Author: GERDA Collaboration, et al, Baudis, Laura, Hiller, Roman, Miloradovic, Michael, Mingazheva, Rizalina, Ransom, Chloe, and University of Zurich
Subjects: 530 Physics, 10192 Physics Institute
Published: 2019

41. Read-out Electronics and Signal Processing in GERDA and Future Prospects

Author: D, Valerio and GERDA Collaboration
Published: 2019
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42. GERDA results and the future perspectives for the neutrinoless double beta decay search using 76Ge

Author: GERDA Collaboration, Baudis, Laura, Hiller, Roman, Miloradovic, Michael, Mingazheva, Rizalina, et al, and University of Zurich
Subjects: 530 Physics, 3103 Astronomy and Astrophysics, 10192 Physics Institute, 3107 Atomic and Molecular Physics, and Optics, 3106 Nuclear and High Energy Physics
Published: 2018
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43. Improved Limit on Neutrinoless Double-β Decay of Ge76 from GERDA Phase II

Author: GERDA Collaboration, Baudis, Laura, Hiller, Roman, Miloradovic, Michael, Mingazheva, Rizalina, et al, and University of Zurich
Subjects: 530 Physics, 10192 Physics Institute, 3100 General Physics and Astronomy
Published: 2018
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44. Highlights from GERDA: Probing the Majorana Neutrino Mass at 100 meV

Author: Cattadori on behalf of the GERDA Collaboration, Carla Maria, primary
Published: 2019
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45. Flux Modulations seen by the Muon Veto of the GERDA Experiment

Author: GERDA Collaboration, Agostini, M, Allardt, M, Bakalyarov, A M, et al, Baudis, L, Benato, G, Walter, M, University of Zurich, and GERDA Collaboration
Subjects: 530 Physics, 3103 Astronomy and Astrophysics, 10192 Physics Institute
Published: 2016

46. The $0\nu\beta\beta$ Experiment GERDA Latest Phase I Results and Phase II Upgrade

Author: von Sturm, Katharina and GERDA Collaboration
Abstract: Sturm, Katharina von "The $0\nu\beta\beta$ Experiment GERDA Latest Phase I Results and Phase II Upgrade" in 12th "Patras" Workshop on Axions, WIMPs and WISPs, PATRAS 2016 / Kim, Younglm, Lindner, Axel, Semertzidis, Yannis K. (eds.), Verlag Deutsches Elektronen-Synchrotron : 2017 ; PATRAS 2016 : 12th "Patras" Workshop on Axions, WIMPs and WISPs, 2016-06-20 - 2016-06-24, Jeju Island 12th Patras Workshop on Axions, WIMPs and WISPs, AXION-WIMP 2016, Jeju Island, South Korea, 20 Jun 2016 - 24 Jun 2016; Hamburg : Verlag Deutsches Elektronen-Synchrotron, DESY-PROC, 137-140 (2017). doi:10.3204/DESY-PROC-2009-03/VonSturm_Katharina, \textsc{Gerda} published the best limit on $^{76}$Ge $0\nu\beta\beta$ decay's half-life of $T_{1/2}^{0\nu}>2.1\cdot10^{25}$yr ($90\%$C.L.) in 2013. Subsequently, exotic decay modes with Majoron emission were investigated obtaining half-life limits $\sim 10^{23}$yr for spectral indices $n=1,2,3,7$. The half-life measurement of $2\nu\beta\beta$ from $^{76}$Ge to $^{76}$Se g.s. was reevaluated with an uncertainty $, Published by Verlag Deutsches Elektronen-Synchrotron, Hamburg
Published: 2017
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47. Search of Neutrinoless Double Beta Decay with the GERDA Experiment

Author: GERDA Collaboration, Agostini, M, Allardt, M, Bakalyarov, A M, et al, Baudis, L, Benato, G, Walter, M, University of Zurich, and Benato, G
Subjects: 530 Physics, 10192 Physics Institute, 3106 Nuclear and High Energy Physics
Published: 2016

48. The GERDA Experiment: Search for the Neutrinoless Double Beta Decay

Author: Miloradovic, Michael and Gerda Collaboration
Abstract: Miloradovic, Michael "The GERDA Experiment: Search for the Neutrinoless Double Beta Decay" in Proceedings, Magellan Workshop: Connecting Neutrino Physics and Astronomy / Dahmke, Stefan K.G., Meyer, Mikko, Vanhoefer, Laura (eds.), Deutsches Elektronen-Synchrotron, DESY : 2016 ; Magellan Workshop, 2016-03-17 - 2016-03-18, Hamburg Magellan Workshop, Hamburg, Germany, 17 Mar 2016 - 18 Mar 2016 ; DESY-PROC 41-46(2016). doi:10.3204/DESY-PROC-2016-05/34, The Germanium Detector Array (Gerda) experiment is searching for the neutrinoless double beta decay of $^{76}$Ge. The observation of this Beyond the Standard Model process would prove the existence of a neutrino Majorana mass component and provide information on the neutrino mass hierarchy and absolute mass scale. {\sc Gerda} operates enriched germanium diodes, acting simultaneously as the source and detector material, directly submerged in liquid argon. Phase I achieved the world's best lower limit of $T^{\,0\nu\beta\beta}_{1/2}>2.1\cdot10^{25}$~yr (90\% C.L.). With the recent completion of the upgrade to Phase II, an additional 20~kg of germanium detectors -- for a total of 35~kg -- and a liquid argon veto system have been implemented. The goal is an order of magnitude lower background with a projected sensitivity of $1.4\cdot10^{26}$~yr for $T^{\,0\nu\beta\beta}_{1/2}$., Published by Deutsches Elektronen-Synchrotron, DESY, Hamburg
Published: 2016
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49. Limit on the Radiative Neutrinoless Double Electron Capture of 36Ar from GERDA Phase I

Author: GERDA Collaboration, Agostini, M, Allardt, M, Bakalyarov, A M, et al, Baudis, L, Benato, G, Kish, A, Miloradovic, M, Mingazheva, R, Walter, M, and University of Zurich
Subjects: 530 Physics, 10192 Physics Institute, 2201 Engineering (miscellaneous), 3101 Physics and Astronomy (miscellaneous)
Published: 2016

50. Results on ββ decay with emission of two neutrinos or Majorons in 76Ge from GERDA Phase I

Author: GERDA Collaboration, Agostini, M, Allardt, M, Bakalyarov, AM, Balata, M, Barabanov, I, Barros, N, Baudis, L, Bauer, C, Becerici-Schmidt, N, Bellotti, E, Belogurov, S, Belyaev, ST, Benato, G, Bettini, A, Bezrukov, L, Bode, T, Borowicz, D, Brudanin, V, Brugnera, R, Budjáš, D, Caldwell, A, Cattadori, C, Chernogorov, A, D’Andrea, V, Demidova, EV, di Vacri, A, Domula, A, Doroshkevich, E, Egorov, V, Falkenstein, R, Fedorova, O, Freund, K, Frodyma, N, Gangapshev, A, Garfagnini, A, Grabmayr, P, Gurentsov, V, Gusev, K, Hegai, A, Heisel, M, Hemmer, S, Heusser, G, Hofmann, W, Hult, M, Inzhechik, LV, Csáthy, J Janicskó, Jochum, J, Junker, M, Kazalov, V, Kihm, T, Kirpichnikov, IV, Kirsch, A, Klimenko, A, Knöpfle, KT, Kochetov, O, Kornoukhov, VN, Kuzminov, VV, Laubenstein, M, Lazzaro, A, Lebedev, VI, Lehnert, B, Liao, HY, Lindner, M, Lippi, I, Lubashevskiy, A, Lubsandorzhiev, B, Lutter, G, Macolino, C, Majorovits, B, Maneschg, W, Medinaceli, E, Misiaszek, M, Moseev, P, Nemchenok, I, Palioselitis, D, Panas, K, Pandola, L, Pelczar, K, Pullia, A, Riboldi, S, Rumyantseva, N, Sada, C, Salathe, M, Schmitt, C, Schneider, B, Schönert, S, Schreiner, J, Schütz, A-K, Schulz, O, Schwingenheuer, B, Selivanenko, O, Shirchenko, M, Simgen, H, Smolnikov, A, Stanco, L, Stepaniuk, M, Ur, CA, Vanhoefer, L, and Vasenko, AA
Subjects: Quantum Physics, Particle and Plasma Physics, Molecular, Nuclear, nucl-ex, physics.ins-det, Atomic, Nuclear & Particles Physics
Abstract: A search for neutrinoless ββ decay processes accompanied with Majoron emission has been performed using data collected during PhaseI of the GERmanium Detector Array (GERDA) experiment at the Laboratori Nazionali del Gran Sasso of INFN (Italy). Processes with spectral indices n = 1, 2, 3, 7 were searched for. No signals were found and lower limits of the order of 1023yr on their half-lives were derived, yielding substantially improved results compared to previous experiments with 76Ge. A new result for the half-life of the neutrino-accompanied ββ decay of 76Ge with significantly reduced uncertainties is also given, resulting in (Formula presented.) yr.
Published: 2015

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