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1. 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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2. 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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3. 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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4. 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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5. 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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6. Modeling of GERDA Phase II data

Author

The GERDA collaboration, M. Agostini, A. M. Bakalyarov, M. Balata, I. Barabanov, L. Baudis, C. Bauer, E. Bellotti, S. Belogurov, A. Bettini, L. Bezrukov, D. Borowicz, 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, A. Domula, E. Doroshkevich, V. Egorov, F. Fischer, M. Fomina, A. Gangapshev, A. Garfagnini, C. Gooch, P. Grabmayr, V. Gurentsov, K. Gusev, J. Hakenmüller, 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. Klimenko, R. Kneißl, 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, M. Miloradovic, R. Mingazheva, M. Misiaszek, P. Moseev, I. Nemchenok, K. Panas, L. Pandola, K. Pelczar, L. Pertoldi, P. Piseri, A. Pullia, C. Ransom, 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, H. Simgen, A. Smolnikov, D. Stukov, L. Vanhoefer, 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, and G. Zuzel

Subjects
Dark Matter and Double Beta Decay (experiments), Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract

Abstract The GERmanium Detector Array (Gerda) experiment at the Gran Sasso underground laboratory (LNGS) of INFN is searching for neutrinoless double-beta (0νββ) decay of 76Ge. The technological challenge of Gerda is to operate in a “background-free” regime in the region of interest (ROI) after analysis cuts for the full 100 kg·yr target exposure of the experiment. A careful modeling and decomposition of the full-range energy spectrum is essential to predict the shape and composition of events in the ROI around Q ββ for the 0νββ search, to extract a precise measurement of the half-life of the double-beta decay mode with neutrinos (2νββ) and in order to identify the location of residual impurities. The latter will permit future experiments to build strategies in order to further lower the background and achieve even better sensitivities. In this article the background decomposition prior to analysis cuts is presented for Gerda Phase II. The background model fit yields a flat spectrum in the ROI with a background index (BI) of 16.04 − 0.85 + 0.78 · 10 − 3 $$ {16.04}_{-0.85}^{+0.78}\cdotp {10}^{-3} $$ cts/(keV·kg·yr) for the enriched BEGe data set and 14.68 − 0.52 + 0.47 · 10 − 3 $$ {14.68}_{-0.52}^{+0.47}\cdotp {10}^{-3} $$ cts/(keV·kg·yr) for the enriched coaxial data set. These values are similar to the one of Phase I despite a much larger number of detectors and hence radioactive hardware components.

Published
2020
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7. 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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8. 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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9. Calibration of the Gerda experiment

Author

T. Wester, A.A. Smolnikov, E. V. Demidova, J. Janicskó Csáthy, C. Cattadori, Anna Julia Zsigmond, Kai Zuber, A. V. Veresnikova, D. R. Zinatulina, A. Chernogorov, R. Hiller, T. Comellato, S. Belogurov, I. Zhitnikov, R. Mingazheva, B. Schwingenheuer, C. Bauer, P. Krause, Igor Nemchenok, Stefano Riboldi, L. Shtembari, Bela Majorovits, I. V. Kirpichnikov, Paolo Piseri, J. Huang, O.I. Kochetov, Mikael Hult, M. Misiaszek, M. Miloradovic, Laura Baudis, M. Fomina, S. Hemmer, J. Hakenmüller, G. R. Araujo, S. Schönert, A. M. Gangapshev, C. Vignoli, A. Garfagnini, M. Schütt, Werner Hofmann, O. Schulz, R. Kneißl, I. R. Barabanov, L. Manzanillas, C. Gooch, S. V. Zhukov, Josef Jochum, A. Lubashevskiy, Y. Kermaïdic, K. N. Gusev, V. D'Andrea, K. T. Knöpfle, Ivano Lippi, D. Stukov, Allen Caldwell, C. Wiesinger, V. I. Gurentsov, M. Balata, M. Shirchenko, R. Brugnera, L. B. Bezrukov, K. von Sturm, Bayarto Lubsandorzhiev, V. B. Brudanin, E. Bossio, A. A. Vasenko, E. Shevchik, V. V. Kazalov, V. V. Kuzminov, L. V. Inzhechik, A. Pullia, Franz Dieter Fischer, E. Doroshkevich, Matteo Agostini, F. Salamida, Cinzia Sada, B. Zatschler, M. M. Wojcik, W. Maneschg, E. A. Yanovich, E. Bellotti, M. Schwarz, C. Ransom, Hardy Simgen, G. Zuzel, L. Pertoldi, A.-K. Schütz, N. Di Marco, M. Junker, Manfred Lindner, O. Selivanenko, C. Macolino, M. Laubenstein, V. N. Kornoukhov, V. Bothe, K. Pelczar, Alessandro Bettini, Y. Müller, Guillaume Lutter, A. M. Bakalyarov, Jochen Schreiner, Th. Kihm, V. Biancacci, H. Khushbakht, P. Moseev, Luciano Pandola, L. Rauscher, A. A. Klimenko, A. Zschocke, N. Rumyantseva, P. Grabmayr, and GERDA Collaboration

Subjects
Physics - Instrumentation and Detectors, Physics and Astronomy (miscellaneous), Regular Article - Experimental Physics, Physics::Instrumentation and Detectors, chemistry.chemical_element, FOS: Physical sciences, Germanium, Electron, QC770-798, Astrophysics, 01 natural sciences, Standard Model, Nuclear physics, Nuclear and particle physics. Atomic energy. Radioactivity, 0103 physical sciences, Calibration, Nuclear Experiment (nucl-ex), 010306 general physics, Nuclear Experiment, Engineering (miscellaneous), Physics, 010308 nuclear & particles physics, Resolution (electron density), Detector, Instrumentation and Detectors (physics.ins-det), Semiconductor detector, QB460-466, chemistry, GERDA - Abteilung Hinton, High Energy Physics::Experiment, Energy (signal processing)
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

10. Final Results of GERDA on the Search for Neutrinoless Double-ß Decay

Author

V. I. Gurentsov, Bayarto Lubsandorzhiev, A. Lubashevskiy, T. Wester, A. A. Vasenko, A.A. Smolnikov, J. Huang, O.I. Kochetov, J. Janicskó Csáthy, R. Mingazheva, C. Cattadori, Anna Julia Zsigmond, Kai Zuber, A. M. Gangapshev, B. Schwingenheuer, R. Brugnera, V. V. Kuzminov, Matteo Agostini, V. V. Kazalov, O. Schulz, E. Doroshkevich, Franz Dieter Fischer, A.-K. Schütz, I. Zhitnikov, I. V. Kirpichnikov, Werner Hofmann, N. Di Marco, Paolo Piseri, G. R. Araujo, D. R. Zinatulina, A. Lazzaro, D. Stukov, M. Schwarz, M. Miloradovic, Allen Caldwell, A. Garfagnini, W. Maneschg, S. Schönert, Josef Jochum, E. A. Yanovich, M. Balata, C. Bauer, Stefano Riboldi, L. Shtembari, F. Salamida, Manfred Lindner, V.B. Brudanin, C. Ransom, Hardy Simgen, I. R. Barabanov, V. D'Andrea, C. Gooch, S. V. Zhukov, P. Krause, Igor Nemchenok, Mikael Hult, K. Panas, K. von Sturm, Bela Majorovits, K. N. Gusev, J. Hakenmüller, M. Misiaszek, R. Kneißl, K. T. Knöpfle, L. Manzanillas, E. V. Demidova, T. Comellato, L. Pertoldi, S. Hemmer, Y. Kermaïdic, Laura Baudis, A. Pullia, G. Zuzel, O. Selivanenko, S. Belogurov, Ivano Lippi, C. Wiesinger, A. V. Veresnikova, M. Shirchenko, A. Chernogorov, M. Fomina, R. Hiller, E. Bossio, M. Schütt, D. Borowicz, L. V. Inzhechik, Cinzia Sada, B. Zatschler, P. Grabmayr, Alessandro Bettini, Y. Müller, C. Macolino, V. Bothe, V. N. Kornoukhov, K. Pelczar, M. Junker, C. Vignoli, Guillaume Lutter, A. M. Bakalyarov, L. Rauscher, A. Zschocke, Jochen Schreiner, V. Biancacci, L. B. Bezrukov, E. Shevchik, M. M. Wojcik, E. Bellotti, Th. Kihm, H. Khushbakht, P. Moseev, Luciano Pandola, A. A. Klimenko, N. Rumyantseva, M. Laubenstein, and GERDA collaboration

Subjects
Physics, Physics - Instrumentation and Detectors, Signal region, General Physics and Astronomy, chemistry.chemical_element, Germanium, 7. Clean energy, 01 natural sciences, Cosmology, High Energy Physics - Experiment, 3. Good health, Semiconductor detector, Nuclear physics, chemistry, GE-76, 0103 physical sciences, GERDA - Abteilung Hinton, Liquid argon, Beta (velocity), SHAPE, High Energy Physics::Experiment, Sensitivity (control systems), 010306 general physics, Nuclear Experiment, Diode
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

11. First Search for Bosonic Superweakly Interacting Massive Particles with Masses up to <math><mrow><mn>1</mn><mtext> </mtext><mtext> </mtext><mi>MeV</mi><mo>/</mo><msup><mrow><mi>c</mi></mrow><mrow><mn>2</mn></mrow></msup></mrow></math> with GERDA

Author

M, Agostini, A M, Bakalyarov, M, Balata, I, Barabanov, L, Baudis, C, Bauer, E, Bellotti, S, Belogurov, A, Bettini, L, Bezrukov, D, Borowicz, 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, V, Egorov, F, Fischer, M, Fomina, A, Gangapshev, A, Garfagnini, C, Gooch, P, Grabmayr, V, Gurentsov, K, Gusev, J, Hakenmüller, S, Hemmer, R, Hiller, W, Hofmann, 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, A, Lazzaro, M, Lindner, I, Lippi, A, Lubashevskiy, B, Lubsandorzhiev, G, Lutter, C, Macolino, B, Majorovits, W, Maneschg, M, Miloradovic, R, Mingazheva, M, Misiaszek, P, Moseev, I, Nemchenok, K, Panas, 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, 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, and G, Zuzel

Abstract

We present the first search for bosonic superweakly interacting massive particles (super-WIMPs) as keV-scale dark matter candidates performed with the GERDA experiment. GERDA is a neutrinoless double-β decay experiment which operates high-purity germanium detectors enriched in Ge76 in an ultralow background environment at the Laboratori Nazionali del Gran Sasso (LNGS) of INFN in Italy. Searches were performed for pseudoscalar and vector particles in the mass region from 60 keV/c2 to 1 MeV/c2. 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/c2 have been set. As an example, at a mass of 150 keV/c2 the most stringent direct limits on the dimensionless couplings of axionlike particles and dark photons to electrons of gae<3×10−12 and α′/α<6.5×10−24 at 90% credible interval, respectively, were obtained.

Published
2020

12. First Search for Bosonic Superweakly Interacting Massive Particles with Masses up to 1 MeV/c2 with GERDA

Author

K. Panas, M. M. Wojcik, V. N. Kornoukhov, K. Pelczar, A.-K. Schütz, E. Bellotti, L. B. Bezrukov, E. Shevchik, N. Di Marco, Alessandro Bettini, Manfred Lindner, W. Maneschg, Guillaume Lutter, A. M. Bakalyarov, E. A. Yanovich, T. Wester, A.A. Smolnikov, O.I. Kochetov, Laura Baudis, C. Cattadori, Anna Julia Zsigmond, V. G. Egorov, Kai Zuber, R. Brugnera, O. Selivanenko, R. Mingazheva, Th. Kihm, M. Balata, A. A. Vasenko, V. V. Kuzminov, Matteo Agostini, L. Rauscher, B. Schwingenheuer, M. Junker, Werner Hofmann, V. I. Gurentsov, A. Zschocke, V. Bothe, Paolo Piseri, Allen Caldwell, A. M. Gangapshev, E. Doroshkevich, I. V. Kirpichnikov, H. Khushbakht, P. Moseev, Jochen Schreiner, P. Grabmayr, Luciano Pandola, Bayarto Lubsandorzhiev, L. V. Inzhechik, C. Vignoli, A. Lazzaro, M. Miloradovic, K. von Sturm, A. A. Klimenko, L. Pertoldi, M. Schwarz, A. Garfagnini, O. Schulz, A. Pullia, K. N. Gusev, A. Lubashevskiy, N. Rumyantseva, K. T. Knöpfle, C. Macolino, Cinzia Sada, V.B. Brudanin, C. Ransom, Hardy Simgen, B. Zatschler, I. R. Barabanov, C. Gooch, R. Kneißl, S. V. Zhukov, Josef Jochum, S. Schönert, V. V. Kazalov, Franz Dieter Fischer, T. Comellato, M. Laubenstein, A. V. Veresnikova, A. Chernogorov, R. Hiller, G. Zuzel, P. Krause, Y. Kermaïdic, Ivano Lippi, J. Hakenmüller, C. Wiesinger, M. Shirchenko, V. D'Andrea, M. Fomina, D. Stukov, E. Bossio, F. Salamida, C. Bauer, Stefano Riboldi, M. Misiaszek, M. Schütt, D. Borowicz, J. Janicskó Csáthy, I. Zhitnikov, Igor Nemchenok, Bela Majorovits, E. V. Demidova, S. Belogurov, D. R. Zinatulina, Mikael Hult, and S. Hemmer

Subjects
Physics, Particle physics, 2019-20 coronavirus outbreak, Photon, Coronavirus disease 2019 (COVID-19), Physics::Instrumentation and Detectors, Dark matter, General Physics and Astronomy, chemistry.chemical_element, Germanium, Electron, 7. Clean energy, 01 natural sciences, Pseudoscalar, chemistry, 0103 physical sciences, High Energy Physics::Experiment, Nuclear Experiment, 010306 general physics, Dimensionless quantity
Abstract

We present the first search for bosonic superweakly interacting massive particles (super-WIMPs) as keV-scale dark matter candidates performed with the GERDA experiment. GERDA is a neutrinoless double-s decay experiment which operates high-purity germanium detectors enriched in ^{76}Ge in an ultralow background environment at the Laboratori Nazionali del Gran Sasso (LNGS) of INFN in Italy. Searches were performed for pseudoscalar and vector particles in the mass region from 60 keV/c^{2} to 1 MeV/c^{2}. No evidence for a dark matter signal was observed, and the most stringent constraints on the couplings of super-WIMPs with masses above 120 keV/c^{2} have been set. As an example, at a mass of 150 keV/c^{2} the most stringent direct limits on the dimensionless couplings of axionlike particles and dark photons to electrons of g_{ae}

Published
2020

13. Modeling of GERDA Phase II data

Author

A. Domula, M. Schwarz, Laura Baudis, C. Wiesinger, Paolo Piseri, M. Shirchenko, A. Lazzaro, E. Bossio, I. V. Kirpichnikov, Alessandro Bettini, D. R. Zinatulina, M. Miloradovic, E. V. Demidova, A. V. Veresnikova, A. Chernogorov, R. Hiller, R. Kneißl, S. Belogurov, V. D'Andrea, Stefano Riboldi, V.B. Brudanin, C. Ransom, Igor Nemchenok, M. Schütt, M. Misiaszek, Cinzia Sada, B. Zatschler, Bela Majorovits, C. Macolino, Hardy Simgen, W. Maneschg, E. A. Yanovich, P. Moseev, Luciano Pandola, A. A. Klimenko, C. Vignoli, R. Brugnera, Mikael Hult, D. Borowicz, K. N. Gusev, Jochen Schreiner, L. Pertoldi, F. Fischer, Josef Jochum, N. Rumyantseva, V. V. Kuzminov, Matteo Agostini, V. I. Gurentsov, S. Hemmer, Y. Kermaïdic, J. Janicskó Csáthy, Stefan Schönert, E. Doroshkevich, Bayarto Lubsandorzhiev, L. V. Inzhechik, Ivano Lippi, Manfred Lindner, E. Bellotti, T. Wester, A.A. Smolnikov, K. Panas, I. Zhitnikov, V. Bothe, C. Cattadori, Anna Julia Zsigmond, Kai Zuber, A. Zschocke, L. B. Bezrukov, E. Shevchik, A.-K. Schütz, Marcin Wójcik, V. N. Kornoukhov, M. Fomina, P. Grabmayr, K. Pelczar, N. Di Marco, O.I. Kochetov, Guillaume Lutter, A. M. Bakalyarov, I. R. Barabanov, A. M. Gangapshev, C. Gooch, S. V. Zhukov, Thomas Kihm, O. Selivanenko, R. Mingazheva, B. Schwingenheuer, M. Junker, Oliver Schulz, Alberto Pullia, V. G. Egorov, M. Balata, A. Garfagnini, K. T. Knöpfle, T. Comellato, L. Vanhoefer, Matthias Laubenstein, G. Zuzel, V. V. Kazalov, P. Krause, A. A. Vasenko, Christian Bauer, A. Lubashevskiy, J. Hakenmüller, D. Stukov, Werner Hofmann, F. Salamida, Allen Caldwell, and K. von Sturm

Subjects
Physics, Nuclear and High Energy Physics, Particle physics, Physics - Instrumentation and Detectors, 010308 nuclear & particles physics, Spectrum (functional analysis), Detector, Phase (waves), FOS: Physical sciences, Order (ring theory), Instrumentation and Detectors (physics.ins-det), 01 natural sciences, Semiconductor detector, ddc, Region of interest, 0103 physical sciences, Dark Matter and Double Beta Decay (experiments), lcsh:QC770-798, lcsh:Nuclear and particle physics. Atomic energy. Radioactivity, DOUBLE-BETA DECAY, Sensitivity (control systems), Nuclear Experiment (nucl-ex), Neutrino, 010306 general physics, Nuclear Experiment
Abstract

The GERmanium Detector Array (Gerda) experiment at the Gran Sasso underground laboratory (LNGS) of INFN is searching for neutrinoless double-beta (0νββ) decay of 76Ge. The technological challenge of Gerda is to operate in a “background-free” regime in the region of interest (ROI) after analysis cuts for the full 100 kg·yr target exposure of the experiment. A careful modeling and decomposition of the full-range energy spectrum is essential to predict the shape and composition of events in the ROI around Qββ for the 0νββ search, to extract a precise measurement of the half-life of the double-beta decay mode with neutrinos (2νββ) and in order to identify the location of residual impurities. The latter will permit future experiments to build strategies in order to further lower the background and achieve even better sensitivities. In this article the background decomposition prior to analysis cuts is presented for Gerda Phase II. The background model fit yields a flat spectrum in the ROI with a background index (BI) of $$ {16.04}_{-0.85}^{+0.78}\cdotp {10}^{-3} $$ 16.04 − 0.85 + 0.78 · 10 − 3 cts/(keV·kg·yr) for the enriched BEGe data set and $$ {14.68}_{-0.52}^{+0.47}\cdotp {10}^{-3} $$ 14.68 − 0.52 + 0.47 · 10 − 3 cts/(keV·kg·yr) for the enriched coaxial data set. These values are similar to the one of Phase I despite a much larger number of detectors and hence radioactive hardware components.

Published
2019

14. Searching for neutrinoless double beta decay with GERDA

Author

S. Hemmer, V. N. Kornoukhov, Matthias Laubenstein, K. Pelczar, V. G. Egorov, K. T. Knöpfle, R. Brugnera, M. Balata, A. A. Vasenko, Guillaume Lutter, T. Wester, A. M. Bakalyarov, V. I. Lebedev, A.A. Smolnikov, A. Lazzaro, V. V. Kuzminov, Matteo Agostini, C. Wiesinger, L. Vanhoefer, Thomas Kihm, B. Schneider, Anna Julia Zsigmond, M. Shirchenko, E. Doroshkevich, Manfred Lindner, L. B. Bezrukov, Oliver Schulz, Kai Zuber, C. Macolino, L. Stanco, V. V. Kazalov, E. Shevchik, O.I. Kochetov, G. Zuzel, R. Falkenstein, H. V. Kirpichnikov, Jochen Schreiner, Alberto Pullia, A. Garfagnini, D. R. Zinatulina, O. Selivanenko, V.B. Brudanin, C. Ransom, J. Janicsko, A.-K. Schütz, Hardy Simgen, Werner Hofmann, Allen Caldwell, M. Miloradovic, V. I. Gurentsov, K. N. Gusev, A. Hegai, K. Panas, T. Bode, A. Kish, A. M. Gangapshev, Marcin Wójcik, N. Di Marco, R. Mingazheva, Christian Bauer, A. Lubashevskiy, A. Domula, R. Kneiβl, Cinzia Sada, M. Junker, J. Hakenmüller, P. Grabmayr, B. Schwingenheuer, K. von Sturm, Mikael Hult, R. Hiller, Stefano Riboldi, E. Bellotti, Bayarto Lubsandorzhiev, Stefan Schönert, C. Gooch, P. Moseev, Luciano Pandola, V. Wagner, I. Zhitnikov, I. R. Barabanov, Laura Baudis, M. Misiaszek, A. A. Klimenko, M. Heisel, N. Rumyantseva, F. Salamida, S. V. Zhukov, Alessandro Bettini, B. Cattadori, A. Kirsch, Y. Kermaïdic, V. D'Andrea, Ivano Lippi, L. V. Inzhechik, W. Maneschg, E. A. Yanovich, C. Schmitt, A. V. Veresnikova, A. Chernogorov, J. Jochum Csáthy, A. Wegmann, Igor Nemchenok, Bela Majorovits, E. V. Demidova, and S. Belogurov

Subjects
Paper, Physics, History, Particle physics, Physics - Instrumentation and Detectors, Double beta decay, FOS: Physical sciences, Instrumentation and Detectors (physics.ins-det), Nuclear Experiment (nucl-ex), Nuclear Experiment, ddc, Computer Science Applications, Education
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., 8 pages, to appear in the proceedings of TAUP2017

Published
2020

15. Improved Limit on Neutrinoless Double- β Decay of Ge76 from GERDA Phase II

Author

L. V. Inzhechik, D. R. Zinatulina, O. Schulz, Mikael Hult, T. Comellato, V. G. Egorov, M. Balata, V. Wagner, G. Zuzel, L. Vanhoefer, C. Bauer, A. A. Vasenko, T. Bode, Stefano Riboldi, A.-K. Schütz, A. Hegai, N. Di Marco, M. Misiaszek, F. Salamida, R. Brugnera, A. Garfagnini, V. V. Kuzminov, Matteo Agostini, Manfred Lindner, J. Janicskó Csáthy, V. N. Kornoukhov, Y. Kermaïdic, A. Kish, K. Pelczar, A. V. Veresnikova, J. Hakenmüller, I. Zhitnikov, Ivano Lippi, Allen Caldwell, A. Chernogorov, M. Junker, C. Wiesinger, A. Wegmann, M. Shirchenko, R. Hiller, L. Pertoldi, Igor Nemchenok, Guillaume Lutter, A. Kirsch, O. Selivanenko, A. M. Bakalyarov, A. Lubashevskiy, W. Maneschg, S. Hemmer, M. Laubenstein, E. A. Yanovich, K. von Sturm, Bela Majorovits, R. Falkenstein, P. Grabmayr, B. Schneider, I. V. Kirpichnikov, V. I. Gurentsov, V. V. Kazalov, M. Miloradovic, D. Borowicz, J. Biernat, Bayarto Lubsandorzhiev, R. Mingazheva, C. Schmitt, B. Schwingenheuer, R. Kneißl, O.I. Kochetov, Th. Kihm, A. M. Gangapshev, P. Moseev, Luciano Pandola, A. A. Klimenko, Werner Hofmann, M. Heisel, N. Rumyantseva, A. Zschocke, Alessandro Bettini, E. V. Demidova, S. Belogurov, C. Macolino, A. Pullia, Cinzia Sada, V. D'Andrea, A. Lazzaro, S. Schönert, K. Panas, T. Wester, A.A. Smolnikov, C. Cattadori, Anna Julia Zsigmond, Kai Zuber, M. M. Wojcik, E. Bellotti, E. Doroshkevich, L. B. Bezrukov, E. Shevchik, A. Domula, L. Stanco, V.B. Brudanin, C. Ransom, Hardy Simgen, Josef Jochum, I. R. Barabanov, S. V. Zhukov, K. N. Gusev, K. T. Knöpfle, and Laura Baudis

Subjects
Semileptonic decay, Physics, 010308 nuclear & particles physics, Phase (waves), General Physics and Astronomy, chemistry.chemical_element, Germanium, Type (model theory), 01 natural sciences, chemistry, Double beta decay, 0103 physical sciences, Sensitivity (control systems), Atomic physics, 010306 general physics, Energy (signal processing), Diode
Abstract

The GERDA experiment searches for the lepton-number-violating neutrinoless double-β decay of ^{76}Ge (^{76}Ge→^{76}Se+2e^{-}) operating bare Ge diodes with an enriched ^{76}Ge fraction in liquid argon. The exposure for broad-energy germanium type (BEGe) detectors is increased threefold with respect to our previous data release. The BEGe detectors feature an excellent background suppression from the analysis of the time profile of the detector signals. In the analysis window a background level of 1.0_{-0.4}^{+0.6}×10^{-3} counts/(keV kg yr) has been achieved; if normalized to the energy resolution this is the lowest ever achieved in any 0νββ experiment. No signal is observed and a new 90% C.L. lower limit for the half-life of 8.0×10^{25} yr is placed when combining with our previous data. The expected median sensitivity assuming no signal is 5.8×10^{25} yr.

Published
2018

16. Searching Neutrinoless Double Beta Decay with Gerda Phase II

Author

V. D'Andrea, O. Schulz, L. B. Bezrukov, J. Janicskó Csáthy, Elena Sala, E. Shevchik, K. Panas, A. Lazzaro, A. Kirsch, Josef Jochum, Y. Kermaïdic, S. Schönert, W. Maneschg, Ivano Lippi, E. A. Yanovich, Stefano Nisi, R. Mingazheva, I. Zhitnikov, I. R. Barabanov, A. Lubashevskiy, C. Gooch, C. Wiesinger, S. V. Zhukov, B. Schweisshelm, B. Schwingenheuer, A. Garfagnini, M. Shirchenko, T. Wester, A. Domula, A.A. Smolnikov, C. Cattadori, Anna Julia Zsigmond, Kai Zuber, V. I. Gurentsov, T. Comellato, V. Kazalov, A. Kish, A. V. Veresnikova, L. Stanco, V. G. Egorov, M. M. Wojcik, Allen Caldwell, L. Ioannucci, Bayarto Lubsandorzhiev, V. Wagner, M. Balata, C. Ransom, C. Bauer, Stefano Riboldi, M. Junker, C. Hahne, A. Chernogorov, F. Salamida, A. A. Vasenko, Th. Kihm, L. Vanhoefer, Hardy Simgen, T. Bode, L. V. Inzhechik, S. Hemmer, M. Reissfelder, R. Hiller, V. B. Brudanin, K. von Sturm, E. Bellotti, M. Misiaszek, H. Seitz, A. Wegmann, Manfred Lindner, M. Giordano, E. Doroshkevich, Igor Nemchenok, R. Kneißl, B. Schneider, G. Zuzel, P. Moseev, Bela Majorovits, Luciano Pandola, D. R. Zinatulina, Werner Hofmann, A. A. Klimenko, M. Heisel, N. Rumyantseva, M. Laubenstein, P. Holl, J. Hakenmüller, P. Grabmayr, A. Zschocke, I. V. Kirpichnikov, Mikael Hult, E. V. Demidova, M. Miloradovic, O. Selivanenko, S. Belogurov, R. Falkenstein, Jochen Schreiner, C. Schmitt, V. N. Kornoukhov, K. Pelczar, Guillaume Lutter, A. M. Bakalyarov, A.-K. Schütz, A. Hegai, N. Di Marco, K. N. Gusev, R. Brugnera, V. V. Kuzminov, K. T. Knöpfle, Matteo Agostini, Laura Baudis, Gerd Marissens, O.I. Kochetov, A. M. Gangapshev, Alessandro Bettini, C. Macolino, A. Pullia, and Cinzia Sada

Subjects
Physics, Ge-76, Particle physics, Double beta decay, Phase (waves), Beta (velocity), Neutrino, Neutrinoless double beta decay, Semiconductor detector
Abstract

An observation of neutrinoless double beta ([Formula: see text]) decay would allow to shed light onto the nature of neutrinos. Gerda (GERmanium Detector Array) aims to discover this process in a background-free search using [Formula: see text]Ge. The experiment is located at the Laboratori Nazionali del Gran Sasso (LNGS) of the Istituto Nazionale di Fisica Nucleare (INFN) in Italy. Bare, isotopically enriched, high purity germanium detectors are operated in liquid argon. Gerda follows a staged approach. In Phase II 35.6 kg of enriched germanium detectors are operated since December 2015. The application of active background rejection methods, such as a liquid argon scintillation light read-out and pulse shape discrimination of germanium detector signals, allows to reduce the background index to the intended level of [Formula: see text] cts/(keV⋅kg⋅yr). No evidence for the [Formula: see text] decay has been found in 23.2 kg⋅yr of Phase II data, and together with data from Phase I the up-to-date most stringent half-life limit for this process in [Formula: see text]Ge has been established, at a median sensitivity of 5.8⋅10[Formula: see text][Formula: see text]yr the 90[Formula: see text]% C.L. lower limit is 8.0⋅10[Formula: see text][Formula: see text]yr.

Published
2018

17. 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
Physics - Instrumentation and Detectors, Physics and Astronomy (miscellaneous), Phase (waves), FOS: Physical sciences, lcsh:Astrophysics, VETO, nucl-ex, 01 natural sciences, Nuclear physics, DEPENDENCE, Double beta decay, LIQUID ARGON, lcsh:QB460-466, 0103 physical sciences, lcsh:Nuclear and particle physics. Atomic energy. Radioactivity, Sensitivity (control systems), Nuclear Experiment (nucl-ex), BETA-DECAY, 010306 general physics, Engineering (miscellaneous), Nuclear Experiment, physics.ins-det, Physics, 010308 nuclear & particles physics, Detector, Instrumentation and Detectors (physics.ins-det), NEUTRINOS, Upgrade, GE-76, lcsh:QC770-798, SCINTILLATION, Data release, Order of magnitude
Abstract

The GERDA collaboration is performing a sensitive search for neutrinoless double beta decay of $^{76}$Ge 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 (100 kg yr). It will reach thereby a half-life sensitivity of more than 10$^{26}$ yr 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., 31 pages, 34 figures

Published
2017

18. Search for Neutrinoless Double Beta Decay with the GERDA experiment: Phase II

Author

Christian Bauer, A. Lubashevskiy, Oliver Schulz, Alberto Pullia, V. I. Gurentsov, I. R. Barabanov, M. Heisel, C. Macolino, A. Garfagnini, S. V. Zhukov, M. Balata, Bayarto Lubsandorzhiev, J. Schreiner, L. Vanhoefer, T. Bode, E. Doroshkevich, R. Brugnera, M. Salathe, V. V. Kazalov, V. V. Kuzminov, J. Janicsko, Manfred Lindner, T. Wester, Matteo Agostini, A.A. Smolnikov, D. R. Zinatulina, Matthias Laubenstein, C. Cattadori, Kai Zuber, Allen Caldwell, Ivano Lippi, V. Egorov, Josef Jochum, D. Palioselitis, A. Kish, S. Schoenert, K. N. Gusev, A. K. Schuetz, E. Medinaceli, V. Wagner, O. Selivanenko, J. Janicskó Csáthy, Marcin Wójcik, V. D'Andrea, W. Maneschg, C. Gooch, E. A. Yanovich, K. T. Knoepfle, Cinzia Sada, P. Grabmayr, Stefano Riboldi, A. A. Vasenko, K. von Sturm, Giovanni Benato, A. Lazzaro, A. Domula, A. Hegai, E. V. Demidova, Mikael Hult, I. Zhitnikov, M. Misiaszek, B. Schwingenheuer, B. Lehnert, G. Zuzel, C. Wiesinger, R. Mingazheva, M. Shirchenko, M. Allardt, N. Di Marco, V. I. Lebedev, V.B. Brudanin, Hardy Simgen, V. N. Kornoukhov, K. Pelczar, S. Hemmer, Alessandro Bettini, P. Moseev, Luciano Pandola, R. Kneissl, A. Kirsch, S. Belogurov, A. A. Klimenko, Laura Baudis, A. V. Veresnikova, J. Hakenmüller, Guillaume Lutter, A. M. Bakalyarov, D. Borowicz, A. Chernogorov, N. Rumyantseva, K. Panas, B. Schneider, H. Y. Liao, Werner Hofmann, R. Falkenstein, I. V. Kirpichnikov, Luca Stanco, C. Schmitt, M. Miloradovic, A. Wegmann, Igor Nemchenok, F. Salamida, Bela Majorovits, M. Junker, L. B. Bezrukov, E. Shevchik, Thomas Kihm, E. Bellotti, N. Frodyma, O.I. Kochetov, S. T. Belyaev, A. M. Gangapshev, and L. V. Inzhechik

Subjects
Nuclear physics, Physics, chemistry, Double beta decay, Liquid argon, Underground laboratory, Phase (waves), chemistry.chemical_element, Germanium, Sensitivity (control systems), Energy (signal processing), Semiconductor detector
Abstract

The GERmanium Detector Array (GERDA) experiment, located at the Gran Sasso underground laboratory in Italy, is built for the search of $0\nu\beta\beta$ decay in $^{76}$Ge. GERDA operates bare high purity germanium detectors submersed in liquid Argon (LAr). Phase I of the experiment was completed reaching an exposure of about 21 kg$\cdot$yr with a background level of $10^{-2}$ cts/(ke V $\cdot$ kg $\cdot$ yr). GERDA Phase I set a limit on the $0\nu\beta\beta$ decay of $^{76}$Ge of $T_{1/2}^{0\nu} > 2.1 \cdot 10^{25}$ yr. In Phase II 35 kg of germanium detectors enriched in $^{76}$Ge are operated to reach an exposure of 100 kg$\cdot$yr. The design goal is to reduce the background by one order of magnitude to reach the sensitivity for $T_{1/2}^{0\nu} = \mathcal{O} (10^{26} )$ yr. The Phase II setup comprises thirty newly produced Broad Energy Germanium (BEGe) detectors. They contribute to the background reduction with better energy resolution and enhanced pulse shape discrimination. To achieve the necessary background reduction, the setup was complemented with LAr veto. The hardware upgrade for Phase II was finished and all detectors were deployed in December 2015. We present the first results of Phase II with 10.8 kg$\cdot$yr exposure reached in June 2016.

Published
2017

19. Study of the GERDA Phase II background spectrum

Author

V. I. Gurentsov, R. Kneißl, V. G. Egorov, D. Palioselitis, V. D'Andrea, M. Balata, E. Shevzik, L. Vanhoefer, L. B. Bezrukov, V. B. Brudanin, M. Allardt, Matthias Laubenstein, A. V. Veresnikova, M. Salathe, M. Junker, M. M. Wojcik, C. Schmitt, R. Mingazheva, BayarJon Paul Lubsandorzhiev, V. Kazalov, C. Cattadori, B. Schwingenheuer, J. Janicskó Csáthy, A. Domula, R. Brugnera, A. Kish, L. V. Inzhechik, A. Lubashevskiy, A. Kirsch, Oliver Schulz, V. V. Kuzminov, Alessandro Bettini, V. Wagner, I. Zhitnikov, W. Maneschg, E. A. Yanovich, Matteo Agostini, Alberto Pullia, M. Miloradovic, A. Wegmann, C. Bauer, Igor Nemchenok, V. I. Lebedev, A. Garfagnini, Manfred Lindner, L. Stanco, Stefano Riboldi, Bela Majorovits, D. Borowicz, A. Chernogorov, E. Medinaceli, Allen Caldwell, Laura Baudis, I.V. Kirpichnikov, A.A. Vasenko, O. Selivanenko, I. R. Barabanov, B. Lehnert, S. V. Zhukov, Hardy Simgen, E.V. Demidova, S. Belogurov, M. Misiaszek, H. Y. Liao, K. Panas, D. R. Zinatulina, K. N. Gusev, K. T. Knöpfle, C. Gooch, K. von Sturm, E. Bellotti, A.-K. Schütz, Stefan Schönert, A. Hegai, N. Di Marco, E. Doroshkevich, F. Salamida, Cinzia Sada, Giovanni Benato, J. Hakenmüller, Ivano Lippi, C. Wiesinger, Werner Hofmann, Mikael Hult, M. Shirchenko, G. Zuzel, T. Bode, R. Falkenstein, Jochen Schreiner, S. Hemmer, K. Pelczar, Guillaume Lutter, B. Schneider, A. M. Bakalyarov, P. Grabmayr, J. Jochum, T. Wester, A.A. Smolnikov, A. Lazzaro, Kai Zuber, V.N. Kornoukhov, O.I. Kochetov, S. T. Belyaev, A. M. Gangapshev, Th. Kihm, P. Moseev, Luciano Pandola, A. A. Klimenko, M. Heisel, N. Rumyantseva, C. Macolino, and N. Frodyma

Subjects
Physics, History, Background spectrum, Physics and Astronomy (all), Phase (waves), Nuclear Matrix, Astrophysics, Beta Decay, Bolometers, Beta Decay, Bolometers, Nuclear Matrix, Computer Science Applications, Education
Published
2017

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

Author

V. N. Kornoukhov, K. Pelczar, Guillaume Lutter, A. M. Bakalyarov, K. Panas, R. Falkenstein, Jochen Schreiner, C. Schmitt, D. Palioselitis, V. G. Egorov, Allen Caldwell, K. T. Knöpfle, M. Salathe, T. Wester, O. Fedorova, V. I. Gurentsov, B. Lehnert, M. Balata, N. Frodyma, E. Medinaceli, L. Vanhoefer, K. von Sturm, T. Bode, A.A. Smolnikov, C. Cattadori, Kai Zuber, Laura Baudis, Cinzia Sada, Alessandro Bettini, O.I. Kochetov, Bayarto Lubsandorzhiev, A. Kish, R. Mingazheva, K. Freund, Marcin Wójcik, Stefano Riboldi, M. Junker, P. Grabmayr, H. Y. Liao, B. Schwingenheuer, Giovanni Benato, A.-K. Schütz, G. Zuzel, A. Hegai, S. T. Belyaev, V. D'Andrea, M. Misiaszek, C. Wiesinger, J. Jochum, A. M. Gangapshev, M. Shirchenko, V. V. Kazalov, E. V. Demidova, I. R. Barabanov, P. Moseev, Thomas Kihm, K. N. Gusev, D. R. Zinatulina, Luciano Pandola, V. I. Lebedev, A. A. Klimenko, S. V. Zhukov, M. Allardt, R. Brugnera, Stefan Schönert, L. B. Bezrukov, S. Belogurov, M. Heisel, Mikael Hult, E. Shevchik, V. V. Kuzminov, N. Rumyantseva, Matteo Agostini, Christian Bauer, A. Kirsch, A. Wegmann, Manfred Lindner, S. Hemmer, Igor Nemchenok, L. V. Inzhechik, A. Lubashevskiy, E. Doroshkevich, Bela Majorovits, W. Maneschg, A. Lazzaro, A. di Vacri, I. V. Kirpichnikov, Werner Hofmann, A. Domula, E. A. Yanovich, C. Macolino, M. Walter, B. Schneider, O. Selivanenko, R. Kneißl, Ivano Lippi, L. Stanco, V.B. Brudanin, N. Becerici-Schmidt, Hardy Simgen, E. Bellotti, D. Borowicz, M. Stepaniuk, J. Hakemüller, A. V. Veresnikova, J. Janicskó Csáthy, A. Chernogorov, I. Zhitnikov, F. Salamida, Oliver Schulz, Alberto Pullia, A. Garfagnini, Matthias Laubenstein, V. Wagner, A. A. Vasenko, Laboratoire de l'Accélérateur Linéaire (LAL), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), GERDA, and Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11)

Subjects
Physics - Instrumentation and Detectors, radiopurity, Isotopes of germanium, germanium: double-beta decay, chemistry.chemical_element, FOS: Physical sciences, double beta decay, Germanium, Radiopurity, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 7. Clean energy, 01 natural sciences, Uranium and thorium, germanium detectors, Nuclear physics, Double beta decay, 0103 physical sciences, thorium: admixture, germanium: detector, Nuclide, [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], Nuclear Experiment (nucl-ex), uranium and thorium bulk content, 010306 general physics, Nuclear Experiment, background: radioactivity, Physics, Range (particle radiation), 010308 nuclear & particles physics, uranium: admixture, Thorium, Astronomy and Astrophysics, Instrumentation and Detectors (physics.ins-det), Uranium, Germanium detectors, Uranium and thorium bulk content, chemistry, radioactivity, bulk content, DOUBLE-BETA DECAY, Decay chain, GERDA
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
2017

21. First results of GERDA Phase II and consistency with background models

Author

R. Falkenstein, D. Palioselitis, Jochen Schreiner, O. Schulz, I. V. Kirpichnikov, M. Miloradovic, E. V. Demidova, O.I. Kochetov, D. Borowicz, S. T. Belyaev, A. M. Gangapshev, R. Mingazheva, N. Frodyma, V. I. Gurentsov, Alberto Pullia, V. G. Egorov, A. Garfagnini, M. Balata, B. Schwingenheuer, R. Brugnera, V. V. Kuzminov, Bayarto Lubsandorzhiev, R. Kneißl, E. Shevzik, J. Hakenmüller, M. Salathe, Matteo Agostini, V. I. Lebedev, L. Vanhoefer, K. Pelczar, K. N. Gusev, Th. Kihm, Matthias Laubenstein, A. M. Bakalyarov, Marcin Wójcik, E. Doroshkevich, L. V. Inzhechik, P. Grabmayr, Alessandro Bettini, A. Kirsch, Guillaume Lutter, T. Wester, P. Moseev, S. Hemmer, V. D'Andrea, L. B. Bezrukov, Luciano Pandola, J. Jochum, F. Salamida, W. Maneschg, K. T. Knöpfle, A.A. Smolnikov, A. Lazzaro, Christian Bauer, A. A. Klimenko, V.N. Kornoukhov, E. A. Yanovich, A. V. Veresnikova, S. Belogurov, K. Panas, C. Schmitt, A. Wegmann, Igor Nemchenok, Manfred Lindner, A. A. Vasenko, Kai Zuber, E. Medinaceli, M. Heisel, M. Allardt, N. Rumyantseva, C. Cattadori, A. Chernogorov, Bela Majorovits, C. Macolino, A. Lubashevskiy, B. Schneider, I. R. Barabanov, E. Bellotti, C. Gooch, A.-K. Schütz, S. V. Zhukov, A. Hegai, S. Schönert, B. Lehnert, D. R. Zinatulina, G. Zuzel, N. Di Marco, J. Janicskó Csáthy, O. Selivanenko, L. Stanco, V.B. Brudanin, Mikael Hult, Hardy Simgen, A. Kish, A. Domula, V. Wagner, I. Zhitnikov, Cinzia Sada, Giovanni Benato, M. Junker, Laura Baudis, H. Y. Liao, Werner Hofmann, Allen Caldwell, K. von Sturm, Ivano Lippi, V. Kazalov, Stefano Riboldi, M. Misiaszek, C. Wiesinger, M. Shirchenko, and T. Bode

Subjects
Physics, History, Background spectrum, Particle physics, Physics and Astronomy (all), Consistency (statistics), Phase (waves), Liquid argon, DECAY, Computer Science Applications, Education
Published
2017

22. Limit on the radiative neutrinoless double electron capture of $$^{36}$$ 36 Ar from GERDA Phase I

Author

Marc Walter, O.I. Kochetov, J. Janicskó Csáthy, D. Palioselitis, S. T. Belyaev, A. M. Gangapshev, H. Wilsenach, V. I. Gurentsov, R. Brugnera, C. Wiesinger, M. Stepaniuk, M. Heisel, V. V. Kuzminov, Matteo Agostini, B. Lehnert, I. Zhitnikov, A. Domula, C. Macolino, R. Mingazheva, Bayarto Lubsandorzhiev, M. Shirchenko, K. Freund, L. V. Inzhechik, L. B. Bezrukov, B. Schwingenheuer, Oliver Schulz, A. V. Veresnikova, M. Balata, E. Doroshkevich, O. Fedorova, A. Chernogorov, E. V. Demidova, V.B. Brudanin, A. Lazzaro, Alberto Pullia, Hardy Simgen, I. V. Kirpichnikov, E. Medinaceli, I. R. Barabanov, N. Frodyma, A. Garfagnini, M. Miloradovic, W. Maneschg, E. A. Yanovich, S. V. Zhukov, Alessandro Bettini, V. Egorov, S. Belogurov, A.-K. Schütz, V. I. Lebedev, J. Schreiner, A. Hegai, G. Heusser, A. Kirsch, Marcin Wójcik, P. Grabmayr, N. Barros, M. Salathe, L. Vanhoefer, T. Bode, K. T. Knöpfle, Cinzia Sada, Manfred Lindner, P. Moseev, S. Hemmer, Luciano Pandola, R. Kneißl, Matthias Laubenstein, Giovanni Benato, A. A. Klimenko, N. Rumyantseva, V. Wagner, A. Wegmann, O. Selivanenko, C. Gooch, Igor Nemchenok, A. A. Vasenko, K. N. Gusev, B. Schneider, Bela Majorovits, Thomas Kihm, Josef Jochum, V. V. Kazalov, D. R. Zinatulina, G. Zuzel, Ivano Lippi, V. D'Andrea, A. Kish, Mikael Hult, J. Hakenmüller, Stefano Riboldi, K. Panas, M. Misiaszek, M. Allardt, E. Bellotti, A. di Vacri, Werner Hofmann, Allen Caldwell, Luca Stanco, F. Salamida, K. von Sturm, T. Wester, A.A. Smolnikov, C. Cattadori, Kai Zuber, D. Borowicz, Christian Bauer, A. Lubashevskiy, Stefan Schönert, M. Junker, Laura Baudis, V. N. Kornoukhov, H. Y. Liao, K. Pelczar, Guillaume Lutter, A. M. Bakalyarov, R. Falkenstein, and C. Schmitt

Subjects
Physics, Physics and Astronomy (miscellaneous), 010308 nuclear & particles physics, Electron capture, High Energy Physics::Phenomenology, Phase (waves), chemistry.chemical_element, Germanium, Physics::Data Analysis, Statistics and Probability, 01 natural sciences, 7. Clean energy, Lepton number, Semiconductor detector, Nuclear physics, MAJORANA, chemistry, 0103 physical sciences, Radiative transfer, High Energy Physics::Experiment, Neutrino, Nuclear Experiment, 010306 general physics, Engineering (miscellaneous)
Abstract

Neutrinoless double electron capture is a process that, if detected, would give evidence of lepton number violation and the Majorana nature of neutrinos. A search for neutrinoless double electron capture of $^{36}$Ar has been performed with germanium detectors installed in liquid argon using data from Phase I of the GERmanium Detector Array (GERDA) experiment at the Gran Sasso Laboratory of INFN, Italy. No signal was observed and an experimental lower limit on the half-life of the radiative neutrinoless double electron capture of $^{36}$Ar was established: $T_{1/2} > $ 3.6 $\times$ 10$^{21}$ yr at 90 % C.I.

Published
2016

23. New Data Release of GERDA Phase II: Search for 0νββ Decay of 76Ge

Author

Igor Nemchenok, Bela Majorovits, M Agostini, Mikael Hult, I V Kirpichnikov, O. Schulz, A Garfagnini, Allen Caldwell, Manfred Lindner, S. Hemmer, Y. Kermaïdic, A Chernogorov, A. Lubashevskiy, P Moseev, Ivano Lippi, C. Gooch, R. Mingazheva, Th. Kihm, E. Shevchik, R. Kneißl, V. Egorov, O Selivanenko, R Falkenstein, L Bezrukov, A Lazzaro, V.B. Brudanin, C Sada, M Balata, O.I. Kochetov, A. M. Gangapshev, A A Vasenko, C. Bauer, A.-K. Schütz, Hardy Simgen, Luciano Pandola, A. Hegai, B Schneider, S Belogurov, B. Schwingenheuer, E V Demidova, S Riboldi, M Junker, Luca Stanco, N. Di Marco, V V Kuzminov, J. Janicsko Csathy, N Rumyantseva, A. A. Klimenko, A Pullia, A Kish, M. Heisel, V N Kornoukhov, A Domula, M. Misiaszek, E Doroshkevich, A Bettini, Matthias Laubenstein, V Kazalov, Guillaume Lutter, A. M. Bakalyarov, M. Shirchenko, B Lubsandorzhiev, J. Hakenmüller, R. Hiller, K. Panas, L. Vanhoefer, A. Kirsch, C Schmitt, Jochen Schreiner, T. Bode, W. Maneschg, P. Grabmayr, C. Ransom, K. N. Gusev, R Brugnera, K. T. Knöpfle, L V Inzhechik, S. Schönert, Laura Baudis, I Barabanov, J. Jochum, M. Miloradovic, E Bellotti, Werner Hofmann, V D’Andrea, C Macolino, F Salamida, V Gurentsov, A.A. Smolnikov, and C. Cattadori

Subjects
Physics, Nuclear physics, chemistry, Isotope, Double beta decay, Detector, Phase (waves), chemistry.chemical_element, Germanium, Cryogenics, Data release, Semiconductor detector
Abstract

The GERmanium Detector Array (GERDA) experiment is searching for the neutrinoless double beta decay ( 0νββ ) of the isotope 76 Ge. High-purity germanium crystals enriched in 76 Ge, simultaneously used as source and detector, are directly deployed into ultra-pure, cryogenic liquid argon, which acts both as cooling medium and shield against the external radiation. The second phase of the experiment is taking data since end of 2015 with 20 additional kg of custom-made BEGe-type Germanium detectors and an active LAr veto. In this paper we will summarize the results of the last data release of June 2017. No evidence for a possible signal is found: the lower limit for the half-life of 76 Ge is 8.0·1025 yr at 90% CL. The very low residual background found at the Q -value of the decay, about 10-3 cts/(keV · kg · yr), makes Gerda the first experiment in the field to be background-free for the complete design exposure of 100 kg · yr.

Published
2018

24. GERDA results and the future perspectives for the neutrinoless double beta decay search using 76Ge

Author

A. Domula, Allen Caldwell, K. von Sturm, J. Janicskó Csáthy, C. Macolino, A. V. Veresnikova, V.B. Brudanin, Hardy Simgen, A. Chernogorov, V. N. Kornoukhov, K. Pelczar, Christian Bauer, Oliver Schulz, Alberto Pullia, P. Moseev, Luciano Pandola, I. R. Barabanov, I. Zhitnikov, E. Doroshkevich, A. Lubashevskiy, A. A. Klimenko, N. Rumyantseva, Guillaume Lutter, R. Mingazheva, A. M. Bakalyarov, A. Garfagnini, I. V. Kirpichnikov, W. Maneschg, E. A. Yanovich, O.I. Kochetov, S. Hemmer, Matthias Laubenstein, R. Hiller, A. M. Gangapshev, J. Schreiner, Stefano Riboldi, M. Balata, V. Wagner, Alessandro Bettini, E. V. Demidova, B. Schneider, E. Shevchik, R. Kneißl, M. Misiaszek, A. A. Vasenko, V. Egorov, V. I. Gurentsov, L. Vanhoefer, T. Bode, M. Heisel, A. Kirsch, Marcin Wójcik, P. Grabmayr, Y. Kermaïdic, S. Belogurov, V. D'Andrea, M. Miloradovic, L. Pertoldi, Bayarto Lubsandorzhiev, Ivano Lippi, A. Wegmann, L. V. Inzhechik, Igor Nemchenok, V. V. Kazalov, C. Wiesinger, M. Shirchenko, Bela Majorovits, Mikael Hult, K. N. Gusev, M. Giordano, Cinzia Sada, A. Lazzaro, D. Borowicz, R. Brugnera, Stefan Schönert, V. V. Kuzminov, Matteo Agostini, Laura Baudis, A.-K. Schütz, A. Zschocke, N. Di Marco, J. Jochum, Manfred Lindner, J. Biernat, O. Selivanenko, B. Schwingenheuer, E. Bellotti, C. Ransom, L. B. Bezrukov, Werner Hofmann, S. V. Zhukov, Thomas Kihm, M. Junker, K. T. Knöpfle, T. Comellato, G. Zuzel, J. Hakenmüller, K. Panas, Luca Stanco, F. Salamida, T. Wester, A.A. Smolnikov, C. Cattadori, Anna Julia Zsigmond, Kai Zuber, and D. Zinatulina

Subjects
Semileptonic decay, Nuclear and High Energy Physics, MAJORONS, Majorana mass, chemistry.chemical_element, Germanium, 01 natural sciences, Nuclear physics, Atomic and Molecular Physics, Double beta decay, 0103 physical sciences, Neutrinoless double beta decay, lepton number violation, Atomic and Molecular Physics, and Optics, Astronomy and Astrophysics, 010306 general physics, Diode, Physics, 010308 nuclear & particles physics, Detector, Beta decay, Semiconductor detector, chemistry, Liquid argon, and Optics
Abstract

The GERmanium Detector Array (GERDA) is a low background experiment at the Laboratori Nazionali del Gran Sasso (LNGS) of INFN designed to search for the rare neutrinoless double beta decay ([Formula: see text]) of [Formula: see text]Ge. In the first phase (Phase I) of the experiment, high purity germanium diodes were operated in a “bare” mode and immersed in liquid argon. The overall background level of [Formula: see text] was a factor of ten better than those of its predecessors. No signal was found and a lower limit was set on the half-life for the [Formula: see text] decay of [Formula: see text]Ge [Formula: see text] yr (90% CL), while the corresponding median sensitivity was [Formula: see text] yr (90% CL). A second phase (Phase II) started at the end of 2015 after a major upgrade. Thanks to the increased detector mass and performance of the enriched germanium diodes and due to the introduction of liquid argon instrumentation techniques, it was possible to reduce the background down to [Formula: see text]. After analyzing 23.2 kg[Formula: see text]⋅[Formula: see text]yr of these new data no signal was seen. Combining these with the data from Phase I a stronger half-life limit of the [Formula: see text]Ge [Formula: see text] decay was obtained: [Formula: see text] yr (90% CL), reaching a sensitivity of [Formula: see text] yr (90% CL). Phase II will continue for the collection of an exposure of 100 kg[Formula: see text]yr. If no signal is found by then the GERDA sensitivity will have reached [Formula: see text] yr for setting a 90% CL. limit. After the end of GERDA Phase II, the flagship experiment for the search of [Formula: see text] decay of [Formula: see text]Ge will be LEGEND. LEGEND experiment is foreseen to deploy up to 1-ton of [Formula: see text]Ge. After ten years of data taking, it will reach a sensitivity beyond 10[Formula: see text] yr, and hence fully cover the inverted hierarchy region.

Published
2018

25. Results on $$\beta \beta $$ β β decay with emission of two neutrinos or Majorons in $$^{76}$$ 76 Ge from GERDA Phase I

Author

M. Shirchenko, I. V. Kirpichnikov, C. A. Ur, E. V. Demidova, N. Barros, Oliver Schulz, V. Egorov, E. Doroshkevich, Alberto Pullia, O. Fedorova, A. V. Veresnikova, A. Chernogorov, K. N. Gusev, Alessandro Bettini, Allen Caldwell, J. Janicskó Csáthy, R. Falkenstein, A. Kirsch, A. Garfagnini, Stefano Riboldi, D. Borowicz, N. Frodyma, S. Belogurov, E. Medinaceli, D. R. Zinatulina, M. Misiaszek, A. Domula, M. Balata, O.I. Kochetov, Stefan Schönert, D. Budjáš, C. Macolino, B. Lehnert, A. Wegmann, I. Zhitnikov, Igor Nemchenok, A. Hegai, P. Grabmayr, Cinzia Sada, Thomas Kihm, C. Schmitt, Matthias Laubenstein, Ivano Lippi, P. Zavarise, V.B. Brudanin, Hardy Simgen, Giovanni Benato, I. R. Barabanov, L. Vanhoefer, S. V. Zhukov, L. B. Bezrukov, M. Junker, V. Wagner, K. Panas, M. M. Wojcik, S. T. Belyaev, V. I. Gurentsov, Bela Majorovits, T. Bode, V. N. Kornoukhov, K. Pelczar, K. von Sturm, K. Freund, Luca Stanco, A. A. Vasenko, B. Schwingenheuer, Mikael Hult, A. M. Gangapshev, N. Becerici-Schmidt, M. Heisel, Laura Baudis, H. Wilsenach, S. Hemmer, M. Stepaniuk, Guillaume Lutter, A. M. Bakalyarov, M. Salathe, Manfred Lindner, H. Y. Liao, Christian Bauer, J. Schreiner, E. Bellotti, K. T. Knöpfle, A. Lubashevskiy, R. Brugnera, V. V. Kuzminov, Bayarto Lubsandorzhiev, Matteo Agostini, J. Jochum, P. Moseev, Luciano Pandola, A. A. Klimenko, T. Wester, N. Rumyantseva, A.A. Smolnikov, G. Zuzel, C. Cattadori, Kai Zuber, V. V. Kazalov, G. Heusser, Werner Hofmann, V. I. Lebedev, D. Palioselitis, M. Allardt, A. Lazzaro, O. Selivanenko, V. D'Andrea, W. Maneschg, E. A. Yanovich, L. V. Inzhechik, A. di Vacri, and Marc Walter

Subjects
Nuclear physics, Physics, Physics and Astronomy (miscellaneous), Phase (waves), Order (ring theory), Beta (velocity), Neutrino, Engineering (miscellaneous), Beta decay, Majoron, Semiconductor detector
Abstract

A search for neutrinoless $\beta\beta$ 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 10$^{23}$ yr on their half-lives were derived, yielding substantially improved results compared to previous experiments with $^{76}$Ge. A new result for the half-life of the neutrino-accompanied $\beta\beta$ decay of $^{76}$Ge with significantly reduced uncertainties is also given, resulting in $T^{2\nu}_{1/2} = (1.926 \pm 0.095)\cdot10^{21}$ yr.

Published
2015

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

Author

M. Shirchenko, D. Palioselitis, Laura Baudis, I. V. Kirpichnikov, J. Janicskó Csáthy, I. Zhitnikov, Oliver Schulz, H. Y. Liao, W. Maneschg, E. A. Yanovich, N. Barros, Alberto Pullia, J. Jochum, V. N. Kornoukhov, K. Pelczar, A. Garfagnini, L. V. Inzhechik, A.-K. Schütz, A. Hegai, C. Macolino, V. I. Gurentsov, Manfred Lindner, V. V. Kazalov, Allen Caldwell, A. V. Veresnikova, A. Wegmann, Igor Nemchenok, Marc Walter, Guillaume Lutter, A. M. Bakalyarov, V. I. Lebedev, M. Heisel, Bayarto Lubsandorzhiev, A. Chernogorov, T. Wester, B. Lehnert, O. Fedorova, A.A. Smolnikov, Bela Majorovits, K. von Sturm, C. Cattadori, Matthias Laubenstein, P. Zavarise, Kai Zuber, M. Balata, N. Frodyma, R. Brugnera, O. Selivanenko, D. Budjáš, V. Egorov, V. Wagner, K. N. Gusev, E. V. Demidova, L. Vanhoefer, V. V. Kuzminov, Matteo Agostini, T. Bode, Ivano Lippi, A. di Vacri, O.I. Kochetov, Werner Hofmann, E. Bellotti, M. Allardt, A. A. Vasenko, E. Doroshkevich, L. B. Bezrukov, E. Medinaceli, Stefan Schönert, Christian Bauer, S. T. Belyaev, K. Freund, A. Lubashevskiy, A. M. Gangapshev, S. Belogurov, M. Salathe, B. Schwingenheuer, R. Falkenstein, Cinzia Sada, C. Schmitt, Giovanni Benato, Stefano Riboldi, Thomas Kihm, D. R. Zinatulina, C. A. Ur, A. Domula, P. Moseev, G. Heusser, Luciano Pandola, M. Misiaszek, A. A. Klimenko, Marcin Wójcik, P. Grabmayr, N. Rumyantseva, Alessandro Bettini, V.B. Brudanin, A. Kirsch, Hardy Simgen, Mikael Hult, S. Hemmer, J. Schreiner, B. Schneider, I. R. Barabanov, S. V. Zhukov, N. Becerici-Schmidt, H. Wilsenach, M. Stepaniuk, K. Panas, D. Borowicz, Luca Stanco, K. T. Knöpfle, G. Zuzel, V. D'Andrea, A. Lazzaro, and M. Junker

Subjects
Physics - Instrumentation and Detectors, Physics and Astronomy (miscellaneous), Isotopes of germanium, Q value, Physics::Instrumentation and Detectors, Phase (waves), FOS: Physical sciences, GERMANIUM DETECTORS, 01 natural sciences, Noise (electronics), Particle detector, GERDA - Abteilung Hofmann, Nuclear physics, Nuclear magnetic resonance, Double beta decay, 0103 physical sciences, CHARGE MEASUREMENTS, Nuclear Experiment (nucl-ex), 010306 general physics, SILICON, Engineering (miscellaneous), Nuclear Experiment, Physics, 010308 nuclear & particles physics, Instrumentation and Detectors (physics.ins-det), MINIMUM-NOISE, GENIUS, GE-76, DECAY, PROJECT, Radioactive decay, Energy (signal processing), OPTIMUM FILTERS
Abstract

An optimized digital shaping filter has been developed for the GERDA experiment which searches for neutrinoless double beta decay in 76Ge. The GERDA Phase I energy calibration data have been reprocessed and an average improvement of 0.3 keV in energy resolution (FWHM) at the 76Ge Q value for 0\nu\beta\beta decay is obtained. This is possible thanks to the enhanced low-frequency noise rejection of this Zero Area Cusp (ZAC) signal shaping fillter., Comment: 12 pages, 16 figures

Published
2015

27. First results from GERDA Phase II

Author

Manfred Lindner, V. I. Gurentsov, Cinzia Sada, Giovanni Benato, E. Bellotti, V. V. Kazalov, D. Borowicz, Bayarto Lubsandorzhiev, O. Selivanenko, E. Doroshkevich, J. Hakenmüller, Christian Bauer, C. Macolino, J. Janicskó Csáthy, A. Lubashevskiy, L. B. Bezrukov, E. Shevchik, K. T. Knöpfle, R. Mingazheva, R. Brugnera, V. V. Kuzminov, Marcin Wójcik, Matteo Agostini, P. Grabmayr, Werner Hofmann, J. Jochum, L. Stanco, B. Schwingenheuer, Allen Caldwell, O.I. Kochetov, V. Wagner, I. Zhitnikov, A. Wegmann, Alessandro Bettini, B. Lehnert, Igor Nemchenok, A. Kirsch, V.B. Brudanin, G. Zuzel, D. Palioselitis, V. N. Kornoukhov, M. Allardt, Stefano Riboldi, W. Maneschg, Hardy Simgen, E. A. Yanovich, S. T. Belyaev, V. G. Egorov, M. Balata, C. Schmitt, E. Medinaceli, K. Pelczar, K. Panas, A. M. Gangapshev, T. Wester, A.A. Smolnikov, A. Lazzaro, Bela Majorovits, L. V. Inzhechik, P. Moseev, C. Cattadori, Kai Zuber, Guillaume Lutter, A. M. Bakalyarov, L. Vanhoefer, Luciano Pandola, M. Misiaszek, A. A. Klimenko, C. Wiesinger, K. von Sturm, Thomas Kihm, M. Heisel, N. Rumyantseva, M. Shirchenko, Laura Baudis, A. Kish, E. V. Demidova, I. R. Barabanov, A. Domula, F. Salamida, C. Gooch, S. V. Zhukov, A.-K. Schütz, R. Falkenstein, A. Hegai, M. Junker, V. D'Andrea, Jochen Schreiner, N. Di Marco, T. Bode, S. Belogurov, V. I. Lebedev, M. Salathe, Ivano Lippi, D. R. Zinatulina, H. Y. Liao, A. V. Veresnikova, Mikael Hult, A. Chernogorov, S. Hemmer, I. V. Kirpichnikov, M. Miloradovic, B. Schneider, R. Kneißl, K. N. Gusev, Stefan Schönert, Matthias Laubenstein, A. A. Vasenko, N. Frodyma, Oliver Schulz, Alberto Pullia, and A. Garfagnini

Subjects
Nuclear physics, Physics, Semileptonic decay, History, Phase (matter), Nuclear Matrix, Beta Decay, Bolometers, Beta Decay, Bolometers, Nuclear Matrix, Computer Science Applications, Education
Published
2017

28. Active background suppression with the liquid argon scintillation veto of GERDA Phase II

Author

O.I. Kochetov, Oliver Schulz, L. B. Bezrukov, M. Salathe, K. Panas, A. M. Bakalyarov, E. V. Demidova, A. Chernogorov, A. Wegmann, Alberto Pullia, Igor Nemchenok, Christian Bauer, Bela Majorovits, K. Pelczar, S. T. Belyaev, A. Kish, A. Lubashevskiy, D. Palioselitis, D. R. Zinatulina, A. Domula, A. M. Gangapshev, A. Garfagnini, I. R. Barabanov, Guillaume Lutter, C. Gooch, S. V. Zhukov, I. V. Kirpichnikov, B. Lehnert, A.-K. Schütz, Th. Kihm, A. Hegai, Mikael Hult, V. G. Egorov, M. Balata, C. Schmitt, N. Di Marco, M. Allardt, C. Cattadori, L. Stanco, J. Janicskó Csáthy, P. Moseev, L. V. Inzhechik, Luciano Pandola, Ivano Lippi, S. Hemmer, M. Miloradovic, K. N. Gusev, L. Vanhoefer, A. A. Klimenko, V.B. Brudanin, V.N. Kornoukhov, M. Heisel, C. Macolino, Hardy Simgen, R. Falkenstein, Jochen Schreiner, C. Wiesinger, K. T. Knöpfle, N. Rumyantseva, S. Belogurov, R. Brugnera, Manfred Lindner, M. Shirchenko, Matthias Laubenstein, E. Bellotti, E. Doroshkevich, V. V. Kuzminov, B. Schneider, Stefan Schönert, N. Frodyma, M. Junker, Matteo Agostini, V. Wagner, I. Zhitnikov, Laura Baudis, A. V. Veresnikova, O. Selivanenko, Alessandro Bettini, V. I. Lebedev, R. Mingazheva, Cinzia Sada, Marcin Wójcik, P. Grabmayr, B. Schwingenheuer, E. Medinaceli, T. Bode, J. Jochum, H. Y. Liao, Giovanni Benato, V. Kazalov, Stefano Riboldi, M. Misiaszek, V. I. Gurentsov, Bayarto Lubsandorzhiev, E. Shevzik, R. Kneißl, A. Kirsch, W. Maneschg, E. A. Yanovich, V. D'Andrea, A. A. Vasenko, Allen Caldwell, K. von Sturm, Werner Hofmann, D. Borowicz, J. Hakenmüller, T. Wester, A.A. Smolnikov, A. Lazzaro, Kai Zuber, G. Zuzel, and F. Salamida

Subjects
Physics, History, Scintillation, Argon, 010308 nuclear & particles physics, Veto, chemistry.chemical_element, 01 natural sciences, Particle detector, Computer Science Applications, Education, Semiconductor detector, Nuclear physics, chemistry, Impurity, Phase (matter), 0103 physical sciences, Scintillation counter, DETECTORS, 010306 general physics
Published
2017

29. 2νββ decay of 76Ge into excited states with GERDA phase I

Author

null GERDA Collaboration, M Agostini, M Allardt, A M Bakalyarov, M Balata, I Barabanov, N Barros, L Baudis, C Bauer, N Becerici-Schmidt, E Bellotti, S Belogurov, S T Belyaev, 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, A di Vacri, A Domula, E Doroshkevich, V Egorov, R Falkenstein, O Fedorova, K Freund, N Frodyma, A Gangapshev, A Garfagnini, C Gooch, P Grabmayr, V Gurentsov, K Gusev, A Hegai, M Heisel, S Hemmer, G Heusser, W Hofmann, M Hult, L V Inzhechik, J Janicskó Csáthy, J Jochum, M Junker, V Kazalov, T Kihm, I V Kirpichnikov, A Kirsch, A Klimenko, K T Knöpfle, O Kochetov, V N Kornoukhov, V V Kuzminov, M Laubenstein, A Lazzaro, V I Lebedev, B Lehnert, H Y Liao, M Lindner, I Lippi, A Lubashevskiy, B Lubsandorzhiev, G Lutter, C Macolino, B Majorovits, W Maneschg, E Medinaceli, Y Mi, M Misiaszek, P Moseev, I Nemchenok, D Palioselitis, K Panas, L Pandola, K Pelczar, A Pullia, S Riboldi, N Rumyantseva, C Sada, M Salathe, C Schmitt, B Schneider, J Schreiner, O Schulz, B Schwingenheuer, S Schönert, A-K Schütz, O Selivanenko, M Shirchenko, H Simgen, A Smolnikov, L Stanco, M Stepaniuk, C A Ur, L Vanhoefer, A A Vasenko, A Veresnikova, K von Sturm, V Wagner, M Walter, A Wegmann, T Wester, H Wilsenach, M Wojcik, E Yanovich, P Zavarise, I Zhitnikov, S V Zhukov, D Zinatulina, K Zuber, and G Zuzel

Subjects
Physics, Nuclear and High Energy Physics, Particle physics, chemistry, Double beta decay, Excited state, chemistry.chemical_element, Beta (velocity), Germanium, Electron, Neutrino, Beta decay, Order of magnitude
Abstract

Two neutrino double beta decay of $^{76}$Ge to excited states of $^{76}$Se has been studied using data from Phase I of the GERDA experiment. An array composed of up to 14 germanium detectors including detectors that have been isotopically enriched in $^{76}$Ge was deployed in liquid argon. The analysis of various possible transitions to excited final states is based on coincidence events between pairs of detectors where a de-excitation $\gamma$ ray is detected in one detector and the two electrons in the other. No signal has been observed and an event counting profile likelihood analysis has been used to determine Frequentist 90\,\% C.L. bounds for three transitions: ${0^+_{\rm g.s.}-2^+_1}$: $T^{2\nu}_{1/2}>$1.6$\cdot10^{23}$ yr, ${0^+_{\rm g.s.}-0^+_1}$: $T^{2\nu}_{1/2}>$3.7$\cdot10^{23}$ yr and ${0^+_{\rm g.s.}-2^+_2}$: $T^{2\nu}_{1/2}>$2.3$\cdot10^{23}$ yr. These bounds are more than two orders of magnitude larger than those reported previously. Bayesian 90\,\% credibility bounds were extracted and used to exclude several models for the ${0^+_{\rm g.s.}-0^+_1}$ transition.

Published
2015

30. Final Results of GERDA on the Two-Neutrino Double-β Decay Half-Life of ^{76}Ge.

Author

Agostini M, Alexander A, Araujo GR, Bakalyarov AM, 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 PJ, Comellato T, D'Andrea V, Demidova EV, 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 LV, Janicskó Csáthy J, Jochum J, Junker M, Kazalov V, Kermaïdic Y, Khushbakht H, Kihm T, Kilgus K, Kirpichnikov IV, Klimenko A, Knöpfle KT, Kochetov O, Kornoukhov VN, Krause P, Kuzminov VV, 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 AK, Schulz O, Schwarz M, Schwingenheuer B, Selivanenko O, Shevchik E, Shirchenko M, Shtembari L, Simgen H, Smolnikov A, Stukov D, Sullivan S, Vasenko AA, Veresnikova A, Vignoli C, von Sturm K, Wester T, Wiesinger C, Wojcik M, Yanovich E, Zatschler B, Zhitnikov I, Zhukov SV, Zinatulina D, Zschocke A, Zsigmond AJ, Zuber K, and Zuzel G

Abstract

We present the measurement of the two-neutrino double-β decay rate of ^{76}Ge performed with the GERDA Phase II experiment. With a subset of the entire GERDA exposure, 11.8 kg yr, the half-life of the process has been determined: T&#95;{1/2}^{2ν}=(2.022±0.018&#95;{stat}±0.038&#95;{syst})×10^{21}  yr. This is the most precise determination of the ^{76}Ge two-neutrino double-β decay half-life and one of the most precise measurements of a double-β decay process. The relevant nuclear matrix element can be extracted: M&#95;{eff}^{2ν}=(0.101±0.001).

Published
2023
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31. Liquid argon light collection and veto modeling in GERDA Phase II.

Author

Agostini M, Alexander A, Araujo GR, Bakalyarov AM, 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 PJ, Comellato T, D'Andrea V, Demidova EV, 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 LV, Csáthy JJ, Jochum J, Junker M, Kazalov V, Kermaïdic Y, Khushbakht H, Kihm T, Kilgus K, Kirpichnikov IV, Klimenko A, Knöpfle KT, Kochetov O, Kornoukhov VN, Krause P, Kuzminov VV, 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 AK, Schulz O, Schwarz M, Schwingenheuer B, Selivanenko O, Shevchik E, Shirchenko M, Shtembari L, Simgen H, Smolnikov A, Stukov D, Sullivan S, Vasenko AA, Veresnikova A, Vignoli C, von Sturm K, Wegmann A, Wester T, Wiesinger C, Wojcik M, Yanovich E, Zatschler B, Zhitnikov I, Zhukov SV, Zinatulina D, Zschocke A, Zsigmond AJ, Zuber K, and Zuzel G

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., (© The Author(s) 2023.)

Published
2023
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32. Search for tri-nucleon decays of 76 Ge in GERDA.

Author

Agostini M, Alexander A, Araujo G, Bakalyarov AM, 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 PJ, Comellato T, D'Andrea V, Demidova EV, 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 LV, Janicskó Csáthy J, Jochum J, Junker M, Kazalov V, Kermaïdic Y, Khushbakht H, Kihm T, Kilgus K, Kirpichnikov IV, Klimenko A, Knöpfle KT, Kochetov O, Kornoukhov VN, Krause P, Kuzminov VV, 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 AK, Schulz O, Schwarz M, Schwingenheuer B, Selivanenko O, Shevchik E, Shirchenko M, Shtembari L, Simgen H, Smolnikov A, Stukov D, Sullivan S, Vasenko AA, Veresnikova A, Vignoli C, von Sturm K, Wester T, Wiesinger C, Wojcik M, Yanovich E, Zatschler B, Zhitnikov I, Zhukov SV, Zinatulina D, Zschocke A, Zsigmond AJ, Zuber K, and Zuzel G

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 73 m Ga state with half-life of 0.5 s. The nnn-decays of 76 Ge that proceed via 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 × 10 26  yr  (90% credible interval). This result improves previous limits for tri-nucleon decays by one to three orders of magnitude., (© The Author(s) 2023.)

Published
2023
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33. Erratum: First Search for Bosonic Superweakly Interacting Massive Particles with Masses up to 1  MeV/c^{2} with GERDA [Phys. Rev. Lett. 125, 011801 (2020)].

Author

Agostini M, Bakalyarov AM, 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 EV, 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 LV, Janicskó Csáthy J, Jochum J, Junker M, Kazalov V, Kermaïdic Y, Khushbakht H, Kihm T, Kirpichnikov IV, Klimenko A, Kneißl R, Knöpfle KT, Kochetov O, Kornoukhov VN, Krause P, Kuzminov VV, 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 AK, Schulz O, Schwarz M, Schwingenheuer B, Selivanenko O, Shevchik E, Shirchenko M, Simgen H, Smolnikov A, Stukov D, Vasenko AA, Veresnikova A, Vignoli C, von Sturm K, Wester T, Wiesinger C, Wojcik M, Yanovich E, Zatschler B, Zhitnikov I, Zhukov SV, Zinatulina D, Zschocke A, Zsigmond AJ, Zuber K, and Zuzel G

Abstract

This corrects the article DOI: 10.1103/PhysRevLett.125.011801.

Published
2022
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34. Pulse shape analysis in Gerda Phase II.

Author

Agostini M, Araujo G, Bakalyarov AM, 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 EV, Marco ND, 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 LV, Csáthy JJ, Jochum J, Junker M, Kazalov V, Kermaïdic Y, Khushbakht H, Kihm T, Kilgus K, Kirsch A, Kirpichnikov IV, Klimenko A, Knöpfle KT, Kochetov O, Kornoukhov VN, Krause P, Kuzminov VV, 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 AK, Schulz O, Schwarz M, Schwingenheuer B, Selivanenko O, Shevchik E, Shirchenko M, Shtembari L, Simgen H, Smolnikov A, Stukov D, Vasenko AA, Veresnikova A, Vignoli C, Sturm KV, Wagner V, Wester T, Wiesinger C, Wojcik M, Yanovich E, Zatschler B, Zhitnikov I, Zhukov SV, Zinatulina D, Zschocke A, Zsigmond AJ, Zuber K, and Zuzel G

Abstract

The GERmanium Detector Array (Gerda) collaboration searched for neutrinoless double- β 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 year. These methods suppress the background by a factor of about 5 in the region of interest around Q β β = 2039  keV, while preserving ( 81 ± 3 ) % of the signal. In addition, an exhaustive list of parameters is provided which were used in the final data analysis., (© The Author(s) 2022.)

Published
2022
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35. Calibration of the Gerda experiment.

Author

Agostini M, Araujo G, Bakalyarov AM, 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 EV, Marco ND, 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 LV, Csáthy JJ, Jochum J, Junker M, Kazalov V, Kermaïdic Y, Khushbakht H, Kihm T, Kirpichnikov IV, Klimenko A, Kneißl R, Knöpfle KT, Kochetov O, Kornoukhov VN, Krause P, Kuzminov VV, 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 AK, Schulz O, Schwarz M, Schwingenheuer B, Selivanenko O, Shevchik E, Shirchenko M, Shtembari L, Simgen H, Smolnikov A, Stukov D, Vasenko AA, Veresnikova A, Vignoli C, von Sturm K, Wester T, Wiesinger C, Wojcik M, Yanovich E, Zatschler B, Zhitnikov I, Zhukov SV, Zinatulina D, Zschocke A, Zsigmond AJ, Zuber K, and Zuzel G

Abstract

The GERmanium Detector Array (Gerda) collaboration searched for neutrinoless double- β 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 β β = 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- 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 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., (© The Author(s) 2021.)

Published
2021
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36. Characterization of inverted coaxial 76 Ge detectors in GERDA for future double- β decay experiments.

Author

Agostini M, Araujo G, Bakalyarov AM, 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 EV, Marco ND, 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 LV, Janicskó Csáthy J, Jochum J, Junker M, Kazalov V, Kermaïdic Y, Khushbakht H, Kihm T, Kirpichnikov IV, Klimenko A, Kneißl R, Knöpfle KT, Kochetov O, Kornoukhov VN, Krause P, Kuzminov VV, 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 AK, Schulz O, Schwarz M, Schwingenheuer B, Selivanenko O, Shevchik E, Shirchenko M, Shtembari L, Simgen H, Smolnikov A, Stukov D, Vasenko AA, Veresnikova A, Vignoli C, von Sturm K, Wester T, Wiesinger C, Wojcik M, Yanovich E, Zatschler B, Zhitnikov I, Zhukov SV, Zinatulina D, Zschocke A, Zsigmond AJ, Zuber K, and Zuzel G

Abstract

Neutrinoless double- β 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- β decay of 76 Ge ( 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 · year, the background index after analysis cuts is measured to be 4 . 9 - 3.4 + 7.3 × 10 - 4 counts / ( keV · kg · year ) around Q β β . This work confirms the feasibility of IC detectors for the next-generation experiment Legend., (© The Author(s) 2021.)

Published
2021
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37. Final Results of GERDA on the Search for Neutrinoless Double-β Decay.

Author

Agostini M, Araujo GR, Bakalyarov AM, 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 EV, 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 LV, Janicskó Csáthy J, Jochum J, Junker M, Kazalov V, Kermaïdic Y, Khushbakht H, Kihm T, Kirpichnikov IV, Klimenko A, Kneißl R, Knöpfle KT, Kochetov O, Kornoukhov VN, Krause P, Kuzminov VV, 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 AK, Schulz O, Schwarz M, Schwingenheuer B, Selivanenko O, Shevchik E, Shirchenko M, Shtembari L, Simgen H, Smolnikov A, Stukov D, Vasenko AA, Veresnikova A, Vignoli C, von Sturm K, Wester T, Wiesinger C, Wojcik M, Yanovich E, Zatschler B, Zhitnikov I, Zhukov SV, Zinatulina D, Zschocke A, Zsigmond AJ, Zuber K, and Zuzel G

Abstract

The GERmanium Detector Array (GERDA) experiment searched for the lepton-number-violating neutrinoless double-β (0νββ) 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 5.2×10^{-4} counts/(keV kg yr) in the signal region and met the design goal to collect an exposure of 100 kg yr in a background-free regime. When combined with the result of Phase I, no signal is observed after 127.2 kg yr of total exposure. A limit on the half-life of 0νββ decay in ^{76}Ge is set at T&#95;{1/2}>1.8×10^{26}  yr at 90% C.L., which coincides with the sensitivity assuming no signal.

Published
2020
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38. First Search for Bosonic Superweakly Interacting Massive Particles with Masses up to 1  MeV/c^{2} with GERDA.

Author

Agostini M, Bakalyarov AM, 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 EV, 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 LV, Janicskó Csáthy J, Jochum J, Junker M, Kazalov V, Kermaïdic Y, Khushbakht H, Kihm T, Kirpichnikov IV, Klimenko A, Kneißl R, Knöpfle KT, Kochetov O, Kornoukhov VN, Krause P, Kuzminov VV, 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 AK, Schulz O, Schwarz M, Schwingenheuer B, Selivanenko O, Shevchik E, Shirchenko M, Simgen H, Smolnikov A, Stukov D, Vasenko AA, Veresnikova A, Vignoli C, von Sturm K, Wester T, Wiesinger C, Wojcik M, Yanovich E, Zatschler B, Zhitnikov I, Zhukov SV, Zinatulina D, Zschocke A, Zsigmond AJ, Zuber K, and Zuzel G

Abstract

We present the first search for bosonic superweakly interacting massive particles (super-WIMPs) as keV-scale dark matter candidates performed with the GERDA experiment. GERDA is a neutrinoless double-β decay experiment which operates high-purity germanium detectors enriched in ^{76}Ge in an ultralow background environment at the Laboratori Nazionali del Gran Sasso (LNGS) of INFN in Italy. Searches were performed for pseudoscalar and vector particles in the mass region from 60  keV/c^{2} to 1  MeV/c^{2}. No evidence for a dark matter signal was observed, and the most stringent constraints on the couplings of super-WIMPs with masses above 120  keV/c^{2} have been set. As an example, at a mass of 150  keV/c^{2} the most stringent direct limits on the dimensionless couplings of axionlike particles and dark photons to electrons of g&#95;{ae}<3×10^{-12} and α^{'}/α<6.5×10^{-24} at 90% credible interval, respectively, were obtained.

Published
2020
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39. Probing Majorana neutrinos with double-β decay.

Author

Agostini M, Bakalyarov AM, 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 EV, 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 LV, Janicskó Csáthy J, Jochum J, Junker M, Kazalov V, Kermaïdic Y, Kihm T, Kirpichnikov IV, Kirsch A, Kish A, Klimenko A, Kneißl R, Knöpfle KT, Kochetov O, Kornoukhov VN, Krause P, Kuzminov VV, 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 AK, Schulz O, Schwarz M, Schwingenheuer B, Selivanenko O, Shevchik E, Shirchenko M, Simgen H, Smolnikov A, Stanco L, Stukov D, Vanhoefer L, Vasenko AA, Veresnikova A, von Sturm K, Wagner V, Wegmann A, Wester T, Wiesinger C, Wojcik M, Yanovich E, Zhitnikov I, Zhukov SV, Zinatulina D, Zschocke A, Zsigmond AJ, Zuber K, and Zuzel G

Abstract

A discovery that neutrinos are Majorana fermions would have profound implications for particle physics and cosmology. The Majorana character of neutrinos would make possible the neutrinoless double-β (0νββ) decay, a matter-creating process without the balancing emission of antimatter. The GERDA Collaboration searches for the 0νββ decay of 76 Ge by operating bare germanium detectors in an active liquid argon shield. With a total exposure of 82.4 kg⋅year, we observe no signal and derive a lower half-life limit of T 1/2 > 0.9 × 10 26 years (90% C.L.). Our T 1/2 sensitivity, assuming no signal, is 1.1 × 10 26 years. Combining the latter with those from other 0νββ decay searches yields a sensitivity to the effective Majorana neutrino mass of 0.07 to 0.16 electron volts., (Copyright © 2019 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.)

Published
2019
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40. Characterization of 30 76 Ge enriched Broad Energy Ge detectors for GERDA Phase II.

Author

Agostini M, Bakalyarov AM, 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 EV, 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 LV, Csáthy JJ, Jochum J, Junker M, Kazalov V, Kermaïdic Y, Kihm T, Kirpichnikov IV, Kirsch A, Kish A, Klimenko A, Kneißl R, Knöpfle KT, Kochetov O, Kornoukhov VN, Kuzminov VV, Laubenstein M, Lazzaro A, Lehnert B, Liao Y, Lindner M, Lippi I, Lubashevskiy A, Lubsandorzhiev B, Lutter G, Macolino C, Majorovits B, Maneschg W, Marissens G, 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 AK, Schulz O, Schwingenheuer B, Selivanenko O, Shevchik E, Shirchenko M, Simgen H, Smolnikov A, Stanco L, Vanhoefer L, Vasenko AA, Veresnikova A, von Sturm K, Wagner V, Wegmann A, Wester T, Wiesinger C, Wojcik M, Yanovich E, Zhitnikov I, Zhukov SV, Zinatulina D, Zsigmond AJ, Zuber K, and Zuzel G

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 76 Ge 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., (© The Author(s) 2019.)

Published
2019
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41. Improved Limit on Neutrinoless Double-β Decay of ^{76}Ge from GERDA Phase II.

Author

Agostini M, Bakalyarov AM, Balata M, Barabanov I, Baudis L, Bauer C, Bellotti E, Belogurov S, Bettini A, Bezrukov L, Biernat J, Bode T, Borowicz D, Brudanin V, Brugnera R, Caldwell A, Cattadori C, Chernogorov A, Comellato T, D'Andrea V, Demidova EV, Di Marco N, Domula A, Doroshkevich E, Egorov V, Falkenstein R, Gangapshev A, Garfagnini A, Grabmayr P, Gurentsov V, Gusev K, Hakenmüller J, Hegai A, Heisel M, Hemmer S, Hiller R, Hofmann W, Hult M, Inzhechik LV, Janicskó Csáthy J, Jochum J, Junker M, Kazalov V, Kermaidic Y, Kihm T, Kirpichnikov IV, Kirsch A, Kish A, Klimenko A, Kneißl R, Knöpfle KT, Kochetov O, Kornoukhov VN, Kuzminov VV, 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, Pullia A, Ransom C, Riboldi S, Rumyantseva N, Sada C, Salamida F, Schmitt C, Schneider B, Schönert S, Schütz AK, Schulz O, Schwingenheuer B, Selivanenko O, Shevchik E, Shirchenko M, Simgen H, Smolnikov A, Stanco L, Vanhoefer L, Vasenko AA, Veresnikova A, von Sturm K, Wagner V, Wegmann A, Wester T, Wiesinger C, Wojcik M, Yanovich E, Zhitnikov I, Zhukov SV, Zinatulina D, Zschocke A, Zsigmond AJ, Zuber K, and Zuzel G

Abstract

The GERDA experiment searches for the lepton-number-violating neutrinoless double-β decay of ^{76}Ge (^{76}Ge→^{76}Se+2e^{-}) operating bare Ge diodes with an enriched ^{76}Ge fraction in liquid argon. The exposure for broad-energy germanium type (BEGe) detectors is increased threefold with respect to our previous data release. The BEGe detectors feature an excellent background suppression from the analysis of the time profile of the detector signals. In the analysis window a background level of 1.0&#95;{-0.4}^{+0.6}×10^{-3}  counts/(keV kg yr) has been achieved; if normalized to the energy resolution this is the lowest ever achieved in any 0νββ experiment. No signal is observed and a new 90% C.L. lower limit for the half-life of 8.0×10^{25}  yr is placed when combining with our previous data. The expected median sensitivity assuming no signal is 5.8×10^{25}  yr.

Published
2018
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