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

Author

GERDA Collaboration, M. Agostini, A. Alexander, G. Araujo, A. M. Bakalyarov, M. Balata, I. Barabanov, L. Baudis, C. Bauer, S. Belogurov, A. Bettini, L. Bezrukov, V. Biancacci, E. Bossio, V. Bothe, R. Brugnera, A. Caldwell, S. Calgaro, C. Cattadori, A. Chernogorov, P.-J. Chiu, T. Comellato, V. D’Andrea, E. V. Demidova, N. Di Marco, E. Doroshkevich, M. Fomina, A. Gangapshev, A. Garfagnini, C. Gooch, P. Grabmayr, V. Gurentsov, K. Gusev, J. Hakenmüller, S. Hemmer, W. Hofmann, J. Huang, M. Hult, L. V. Inzhechik, J. Janicskó Csáthy, J. Jochum, M. Junker, V. Kazalov, Y. Kermaïdic, H. Khushbakht, T. Kihm, K. Kilgus, I. V. Kirpichnikov, A. Klimenko, K. T. Knöpfle, O. Kochetov, V. N. Kornoukhov, P. Krause, V. V. Kuzminov, M. Laubenstein, M. Lindner, I. Lippi, A. Lubashevskiy, B. Lubsandorzhiev, G. Lutter, C. Macolino, B. Majorovits, W. Maneschg, G. Marshall, M. Misiaszek, M. Morella, Y. Müller, I. Nemchenok, M. Neuberger, L. Pandola, K. Pelczar, L. Pertoldi, P. Piseri, A. Pullia, C. Ransom, L. Rauscher, M. Redchuk, S. Riboldi, N. Rumyantseva, C. Sada, S. Sailer, F. Salamida, S. Schönert, J. Schreiner, A-K. Schütz, O. Schulz, M. Schwarz, B. Schwingenheuer, O. Selivanenko, E. Shevchik, M. Shirchenko, L. Shtembari, H. Simgen, A. Smolnikov, D. Stukov, S. Sullivan, A. A. Vasenko, A. Veresnikova, C. Vignoli, K. von Sturm, T. Wester, C. Wiesinger, M. Wojcik, E. Yanovich, B. Zatschler, I. Zhitnikov, S. V. Zhukov, D. Zinatulina, A. Zschocke, K. Zuber, and G. Zuzel

Subjects
Astrophysics, QB460-466, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract

Abstract A search for full energy depositions from bosonic keV-scale dark matter candidates of masses between 65 and 1021 keV has been performed with data collected during Phase II of the GERmanium Detector Array (Gerda) experiment. Our analysis includes direct dark matter absorption as well as dark Compton scattering. With a total exposure of 105.5 kg years, no evidence for a signal above the background has been observed. The resulting exclusion limits deduced with either Bayesian or Frequentist statistics are the most stringent direct constraints in the major part of the 140–1021 keV mass range. As an example, at a mass of 150 keV the dimensionless coupling of dark photons and axion-like particles to electrons has been constrained to $$\alpha '/\alpha 1.5 \times 10^{24}$$ τ n > 1.5 × 10 24 years and for a proton $$\tau _\textrm{p} > 1.3 \times 10^{24}$$ τ p > 1.3 × 10 24 years at 90% CI. For the electron decay $$e^\text {-} \rightarrow \nu _\textrm{e} \gamma $$ e - → ν e γ a lower limit of $$\tau _\textrm{e} > 5.4\times 10^{25}$$ τ e > 5.4 × 10 25 years at 90% CI has been determined.

Published
2024
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2. 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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3. 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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4. 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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5. 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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6. 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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7. 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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8. Characterization of 30 $$^{76}$$ 76 Ge enriched Broad Energy Ge detectors for GERDA Phase II

Author

M. Agostini, A. M. Bakalyarov, E. Andreotti, M. Balata, I. Barabanov, L. Baudis, N. Barros, C. Bauer, E. Bellotti, S. Belogurov, G. Benato, A. Bettini, L. Bezrukov, T. Bode, D. Borowicz, V. Brudanin, R. Brugnera, D. Budjáš, A. Caldwell, C. Cattadori, A. Chernogorov, V. D’Andrea, E. V. Demidova, N. Di Marco, A. Domula, E. Doroshkevich, V. Egorov, R. Falkenstein, K. Freund, A. Gangapshev, A. Garfagnini, C. Gooch, P. Grabmayr, V. Gurentsov, K. Gusev, J. Hakenmüller, A. Hegai, M. Heisel, S. Hemmer, R. Hiller, W. Hofmann, M. Hult, L. V. Inzhechik, J. Janicskó Csáthy, J. Jochum, M. Junker, V. Kazalov, Y. Kermaïdic, T. Kihm, I. V. Kirpichnikov, A. Kirsch, A. Kish, A. Klimenko, R. Kneißl, K. T. Knöpfle, O. Kochetov, V. N. Kornoukhov, V. V. Kuzminov, M. Laubenstein, A. Lazzaro, B. Lehnert, Y. Liao, M. Lindner, I. Lippi, A. Lubashevskiy, B. Lubsandorzhiev, G. Lutter, C. Macolino, B. Majorovits, W. Maneschg, G. Marissens, M. Miloradovic, R. Mingazheva, M. Misiaszek, P. Moseev, I. Nemchenok, K. Panas, L. Pandola, K. Pelczar, A. Pullia, C. Ransom, S. Riboldi, N. Rumyantseva, C. Sada, F. Salamida, M. Salathe, C. Schmitt, B. Schneider, S. Schönert, A.-K. Schütz, O. Schulz, B. Schwingenheuer, O. Selivanenko, E. Shevchik, M. Shirchenko, H. Simgen, A. Smolnikov, L. Stanco, L. Vanhoefer, A. A. Vasenko, A. Veresnikova, K. von Sturm, V. Wagner, A. Wegmann, T. Wester, C. Wiesinger, M. Wojcik, E. Yanovich, I. Zhitnikov, S. V. Zhukov, D. Zinatulina, A. J. Zsigmond, K. Zuber, G. Zuzel, and GERDA Collaboration

Subjects
Astrophysics, QB460-466, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract

Abstract The GERmanium Detector Array (Gerda) is a low background experiment located at the Laboratori Nazionali del Gran Sasso in Italy, which searches for neutrinoless double-beta decay of $$^{76}$$ 76 Ge into $$^{76}$$ 76 Se+2e$$^-$$ - . Gerda has been conceived in two phases. Phase II, which started in December 2015, features several novelties including 30 new 76Ge enriched detectors. These were manufactured according to the Broad Energy Germanium (BEGe) detector design that has a better background discrimination capability and energy resolution compared to formerly widely-used types. Prior to their installation, the new BEGe detectors were mounted in vacuum cryostats and characterized in detail in the Hades underground laboratory in Belgium. This paper describes the properties and the overall performance of these detectors during operation in vacuum. The characterization campaign provided not only direct input for Gerda Phase II data collection and analyses, but also allowed to study detector phenomena, detector correlations as well as to test the accuracy of pulse shape simulation codes.

Published
2019
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9. Upgrade for Phase II of the Gerda experiment

Author

GERDA Collaboration, M. Agostini, A. M. Bakalyarov, M. Balata, I. Barabanov, L. Baudis, C. Bauer, E. Bellotti, S. Belogurov, S. T. Belyaev, G. Benato, A. Bettini, L. Bezrukov, T. Bode, D. Borowicz, V. Brudanin, R. Brugnera, A. Caldwell, C. Cattadori, A. Chernogorov, V. D’Andrea, E. V. Demidova, N. Di Marco, A. Domula, E. Doroshkevich, V. Egorov, R. Falkenstein, N. Frodyma, A. Gangapshev, A. Garfagnini, P. Grabmayr, V. Gurentsov, K. Gusev, J. Hakenmüller, A. Hegai, M. Heisel, S. Hemmer, R. Hiller, W. Hofmann, M. Hult, L. V. Inzhechik, L. Ioannucci, J. Janicskó Csáthy, J. Jochum, M. Junker, V. Kazalov, Y. Kermaïdic, T. Kihm, I. V. Kirpichnikov, A. Kirsch, A. Kish, A. Klimenko, R. Kneißl, K. T. Knöpfle, O. Kochetov, V. N. Kornoukhov, V. V. Kuzminov, M. Laubenstein, A. Lazzaro, V. I. Lebedev, B. Lehnert, M. Lindner, I. Lippi, A. Lubashevskiy, B. Lubsandorzhiev, G. Lutter, C. Macolino, B. Majorovits, W. Maneschg, E. Medinaceli, M. Miloradovic, R. Mingazheva, M. Misiaszek, P. Moseev, I. Nemchenok, S. Nisi, K. Panas, L. Pandola, K. Pelczar, A. Pullia, C. Ransom, S. Riboldi, N. Rumyantseva, C. Sada, F. Salamida, M. Salathe, C. Schmitt, B. Schneider, S. Schönert, J. Schreiner, A-K. Schütz, O. Schulz, B. Schwingenheuer, O. Selivanenko, E. Shevchik, M. Shirchenko, H. Simgen, A. Smolnikov, L. Stanco, L. Vanhoefer, A. A. Vasenko, A. Veresnikova, K. von Sturm, V. Wagner, A. Wegmann, T. Wester, C. Wiesinger, M. Wojcik, E. Yanovich, I. Zhitnikov, S. V. Zhukov, D. Zinatulina, A. J. Zsigmond, K. Zuber, and G. Zuzel

Subjects
Astrophysics, QB460-466, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract

Abstract The Gerda collaboration is performing a sensitive search for neutrinoless double beta decay of $$^{76}\hbox {Ge}$$ 76Ge at the INFN Laboratori Nazionali del Gran Sasso, Italy. The upgrade of the Gerda experiment from Phase I to Phase II has been concluded in December 2015. The first Phase II data release shows that the goal to suppress the background by one order of magnitude compared to Phase I has been achieved. Gerda is thus the first experiment that will remain “background-free” up to its design exposure ($$\hbox {100 kg}~\hbox {year}$$ 100 kgyear ). It will reach thereby a half-life sensitivity of more than $$10^{26}$$ 1026 year within 3 years of data collection. This paper describes in detail the modifications and improvements of the experimental setup for Phase II and discusses the performance of individual detector components.

Published
2018
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10. 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

11. FPGA Implementation of an NCO Based CDR for the JUNO Front-End Electronics

Author

Antonio Bergnoli, Monica Sisti, Antonio Budano, Michele Montuschi, D. Riondino, Andrey Formozov, A. Cammi, Ezio Previtali, Fabio Mantovani, Barbara Ricci, Agnese Giaz, Rossella Caruso, L. Stanco, S. Parmeggiano, Marco Danilo Claudio Torri, P. Saggese, S. Dusini, W. Bandini, Ivano Lippi, D. Corti, Andrea Fabbri, Cristina Tuve, Andrea Serafini, Cecilia Landini, Richard Ford, L. Votano, M. Mezzetto, Lino Miramonti, Massimiliano Nastasi, D. Basilico, Fausto Ortica, Marco Giammarchi, G. H. Gong, A. Brigatti, Chiara Sirignano, Alessandro Paoloni, M. Bellato, Paolo Lombardi, Xuefeng Ding, Salvatore Costa, Virginia Strati, Jianrun Hu, Xiaoshan Jiang, Andrea Barresi, Agnese Martini, G. Andronico, S. M. Mari, Roberto Isocrate, Sebastiano Aiello, Alessandra Re, Jianmeng Dong, Nicomede Pelliccia, R. Brugnera, Claudio Lombardo, B. Caccianiga, Marco Fargetta, Aldo Romani, Riccardo Bruno, Paolo Montini, Marco Grassi, Catia Clementi, Davide Chiesa, A. Garfagnini, Vito Antonelli, F. Dal Corso, Gioacchino Ranucci, Giuseppe Verde, Cristina Martellini, E. Meroni, Filippo Marini, K. von Sturm, Marini, F., Bellato, M., Bergnoli, A., Brugnera, R., Dal Corso, F., Corti, D., Dong, J., Garfagnini, A., Giaz, A., Gong, G., Hu, J., Isocrate, R., Jiang, X., Lippi, I., Von Sturm, K., Aiello, S., Andronico, G., Antonelli, V., Bandini, W., Basilico, D., Brigatti, A., Barresi, A., Budano, A., Bruno, R., Caccianiga, B., Cammi, A., Caruso, R., Chiesa, D., Clementi, C., Costa, S., Ding, X., Dusini, S., Fabbri, A., Fargetta, M., Ford, R., Formozov, A., Giammarchi, M., Grassi, M., Landini, C., Lombardi, P., Lombardo, C., Mantovani, F., Mari, S. M., Martellini, C., Martini, A., Meroni, E., Mezzetto, M., Miramonti, L., Montini, P., Montuschi, M., Nastasi, M., Ortica, F., Paoloni, A., Parmeggiano, S., Pelliccia, N., Previtali, E., Ranucci, G., Riondino, D., Re, A. C., Ricci, B., Romani, A., Saggese, P., Serafini, A., Sirignano, C., Sisti, M., Stanco, L., Strati, V., Torri, M., Tuve, C., Verde, G., Votano, L., Marini, F, Bellato, M, Bergnoli, A, Brugnera, R, Dal Corso, F, Corti, D, Dong, J, Garfagnini, A, Giaz, A, Gong, G, Hu, J, Isocrate, R, Jiang, X, Lippi, I, Von Sturm, K, Aiello, S, Andronico, G, Antonelli, V, Bandini, W, Basilico, D, Brigatti, A, Barresi, A, Budano, A, Bruno, R, Caccianiga, B, Cammi, A, Caruso, R, Chiesa, D, Clementi, C, Costa, S, Ding, X, Dusini, S, Fabbri, A, Fargetta, M, Ford, R, Formozov, A, Giammarchi, M, Grassi, M, Landini, C, Lombardi, P, Lombardo, C, Mantovani, F, Mari, S, Martellini, C, Martini, A, Meroni, E, Mezzetto, M, Miramonti, L, Montini, P, Montuschi, M, Nastasi, M, Ortica, F, Paoloni, A, Parmeggiano, S, Pelliccia, N, Previtali, E, Ranucci, G, Riondino, D, Re, A, Ricci, B, Romani, A, Saggese, P, Serafini, A, Sirignano, C, Sisti, M, Stanco, L, Strati, V, Torri, M, Tuve, C, Verde, G, and Votano, L

Subjects
Nuclear and High Energy Physics, phase aligner (PA), Clock signal, Computer science, Clock rate, CDR, Clock and data recovery (CDR), eye pattern, field-programmable gate array (FPGA), numerically-controlled oscillator (NCO), phase detector (PD), Phase detector, Digital clock, NO, PE2_2, Electrical and Electronic Engineering, Field-programmable gate array, Clock recovery, CDR ,NCO , phase detector, phase aligner , FPGA , eye pattern, FPGA, Jitter, phase aligner, business.industry, Detector, Nuclear Energy and Engineering, NCO, phase detector, business, Computer hardware
Abstract

This article describes a design of an field-programmable gate array (FPGA) implementation of a clock and data recovery (CDR) system. The core will be integrated in the FPGA configuration for the front-end electronics (FEE) board of the Jiangmen underground neutrino observatory (JUNO) experiment. The front-end will be placed on the main detector, underground and underwater, making the electronics not accessible after installation. The timing and trigger system relies on a synchronous link connection over CAT5e cable (up to 100 m long) between the front-end and the back-end electronics (BEE), where a twisted-pair is dedicated to clock-forwarding. The robustness of the recovery clock system is essential for the stability of the FPGA firmware. The proposed project is intended to improve the clock recovery operation by increasing the immunity of the link to sudden electromagnetic interference (EMI). On top of this, the core allows to free a twisted-pair in the link, since the clock can be recovered from the data and there is no more need for a clock-dedicated transmission. This will optimize the link granting the possibility to implement other features. The design is based on two components: a numerically-controlled oscillator (NCO), in order to create a controlled frequency clock signal, and a digital phase detector (PD) to match the clock frequency with the data rate. NCOs are often coupled with a digital-to-analog converter (DAC) to create direct digital synthesizers (DDSs), which are able to produce analog waveforms of any desired frequency. In the presented case instead, the NCO generates a digital clock signal of an arbitrary frequency, while the PD manages this frequency by intercepting any shifting on the relative phase between the clock and the data. A phase aligner (PA) module guarantees that data are sampled in the middle of the eye pattern, which represents the optimal sampling point. The article presents an overview of the NCO-based CDR design and implementation, together with some tests and results in order to verify the CDR reliability. Moreover, in the last section, some other possible applications of the core are illustrated.

Published
2021

12. 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

13. 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

14. 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
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15. 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

16. 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
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17. 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

18. A Compton scattering setup for pulse shape discrimination studies in germanium detectors

Author

I. Lippi, S. Belogurov, R. Brugnera, M. Turcato, A. Garfagnini, K. von Sturm, D. Rosso, and L. Modenese

Subjects
Physics, Coincidence measurements, Gamma-ray instruments, HPGe detectors, Signal analysis, Radiation, Signal processing, 010308 nuclear & particles physics, business.industry, Detector, Compton scattering, chemistry.chemical_element, Germanium, 01 natural sciences, Signal, Collimated light, Pulse (physics), Optics, chemistry, 0103 physical sciences, Sensitivity (control systems), 010306 general physics, business
Abstract

Pulse shape discrimination is an important handle to improve sensitivity in low background experiments. A dedicated setup was built to investigate the response of high-purity germanium detectors to single Compton scattered events. Using properly collimated γ-ray sources, it is possible to select events with known interaction location. The aim is to correlate the position dependent signal shape with geometrical and electrical properties of the detector. We report on design and performance of the setup with a first look on data.

Published
2017

19. 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
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20. Determination of dead-layer variation in HPGe detectors

Author

Gerd Marissens, Guillaume Lutter, A. Garfagnini, E. Andreotti, Mikael Hult, S. Hemmer, and K. von Sturm

Subjects
Physics, Radiation, Physics::Instrumentation and Detectors, business.industry, Monte Carlo method, Detector, chemistry.chemical_element, Germanium, Particle detector, Semiconductor detector, Optics, chemistry, Measuring instrument, High Energy Physics::Experiment, business, Spectroscopy, Hpge detector
Abstract

The dead-layer uniformity of the top surface of two high purity germanium detectors has been studied using a novel automated scanning set-up that allows a fine-grained topography of a detector's top and lateral surfaces. Comparisons between measurements and Monte Carlo simulations allowed implementation of a dead-layer variation into the detector model, which reproduces the measurements results. The effect of the non-uniform dead-layer on activity determinations based on low-energy γ-rays (i.e. below ~100 keV) has been determined to be of the order of 10% or more.

Published
2014
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21. 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
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22. 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

23. 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
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24. 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

25. 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
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26. 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
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27. 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
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28. Production, characterization and operation of $$^{76}$$ 76 Ge enriched BEGe detectors in GERDA

Author

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

Subjects
Physics, Cryostat, Physics and Astronomy (miscellaneous), Physics::Instrumentation and Detectors, 010308 nuclear & particles physics, Detector, chemistry.chemical_element, Cosmic ray, Germanium, 7. Clean energy, 01 natural sciences, Semiconductor detector, Nuclear physics, chemistry, Double beta decay, 0103 physical sciences, High Energy Physics::Experiment, Nuclear Experiment, 010306 general physics, Engineering (miscellaneous), Energy (signal processing), Diode
Abstract

The GERmanium Detector Array (GERDA) at the Gran Sasso Underground Laboratory (LNGS) searches for the neutrinoless double beta decay (0{\nu}{\beta}{\beta}) of $^{76}$Ge. Germanium detectors made of material with an enriched $^{76}$Ge fraction act simultaneously as sources and detectors for this decay. During Phase I of the experiment mainly refurbished semi-coaxial Ge detectors from former experiments were used. For the upcoming Phase II, 30 new $^{76}$Ge enriched detectors of broad energy germanium (BEGe)-type were produced. A subgroup of these detectors has already been deployed in GERDA during Phase I. The present paper reviews the complete production chain of these BEGe detectors including isotopic enrichment, purification, crystal growth and diode production. The efforts in optimizing the mass yield and in minimizing the exposure of the $^{76}$Ge enriched germanium to cosmic radiation during processing are described. Furthermore, characterization measurements in vacuum cryostats of the first subgroup of seven BEGe detectors and their long-term behavior in liquid argon are discussed. The detector performance fulfills the requirements needed for the physics goals of GERDA Phase~II.

Published
2015
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29. 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

30. Limit on Neutrinoless Double Beta Decay of 76Ge by GERDA

Author

A. Kirsch, W. Maneschg, E. A. Yanovich, Stefano Nisi, P. Zavarise, Josef Jochum, A. Domula, V. Wagner, J. Janicskó Csáthy, M. Salathe, Manfred Lindner, A. A. Vasenko, V. I. Gurentsov, I. Zhitnikov, L. Stanco, B. Lehnert, V.B. Brudanin, O. Volynets, Hardy Simgen, A. D. Ferella, M. Barabè Heider, D. R. Zinatulina, Ivano Lippi, Bayarto Lubsandorzhiev, A. Hegai, O.I. Kochetov, A. Wegmann, A. Lubashevskiy, Igor Nemchenok, A. Garfagnini, Claudio Gotti, S. T. Belyaev, C. Bauer, C. Macolino, A. Chernogorov, Allen Caldwell, Bela Majorovits, L. V. Inzhechik, A. M. Gangapshev, Stefano Riboldi, C.O’. Shaughnessy, P. Grabmayr, R. Brugnera, V. V. Kuzminov, Matteo Agostini, K. Freund, M. Misiaszek, V. I. Lebedev, W. Hampel, E. V. Demidova, K. K. Guthikonda, V. G. Egorov, I. V. Kirpichnikov, B. Schwingenheuer, Mikael Hult, M. Shirchenko, M. Allardt, K. von Sturm, M. Balata, H. Strecker, C. A. Ur, G. Heusser, Alessandro Bettini, K. N. Gusev, S. Belogurov, N. Frodyma, N. Barros, E. Andreotti, T. Bode, A. Lazzaro, Werner Hofmann, K. T. Knöpfle, G. Zuzel, O. Schulz, S. Schönert, S. Hemmer, T. Wester, A.A. Smolnikov, C. Cattadori, Kai Zuber, Laura Baudis, L. B. Bezrukov, E. Shevchik, H. Y. Liao, G. Pessina, M. M. Wojcik, A. A. Machado, F. Cossavella, D. Budjáš, E. Bellotti, M. Tarka, R. Falkenstein, Thomas Kihm, Jochen Schreiner, C. Schmitt, V. N. Kornoukhov, K. Pelczar, Guillaume Lutter, A. M. Bakalyarov, I. R. Barabanov, M. Walter, S. V. Zhukov, M. Laubenstein, Luciano Pandola, N. Becerici-Schmidt, A. A. Klimenko, M. Heisel, N. Rumyantseva, A. Pullia, Cinzia Sada, Giovanni Benato, and M. Junker

Subjects
Physics, Nuclear physics, Particle physics, Isotope, Double beta decay, SEARCH, double beta decay, Limit (mathematics), Physics and Astronomy(all), 0-NU-BETA-BETA DECAY, Semiconductor detector
Abstract

The Gerda experiment at the Laboratori Nazionali del Gran Sasso in Italy uses germanium detectors made from material with an enriched 76Ge isotope fraction to search for neutrinoless double beta decay of this nucleus. Applying a blind analysis we find no signal after an exposure of 21.6 kg·yr and a background of about 0.01 cts/(keV·kg·yr). A half-life limit of Tov1/2> 2.1 · 1025 yr (90% C.L.) is extracted. The previous claim of a signal for 76Ge is excluded with 99% probability in a model independent way.

Published
2015

31. 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
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32. 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
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33. Pulse shape discrimination for GERDA Phase I data

Author

S. Hemmer, V. Wagner, A. A. Vasenko, N. Becerici-Schmidt, J. Schreiner, V. I. Lebedev, Thomas Kihm, H. Strecker, Manfred Lindner, L. V. Inzhechik, T. Wester, A.A. Smolnikov, Alessandro Bettini, M. Barnabe Heider, C. Cattadori, Kai Zuber, Allen Caldwell, V. I. Gurentsov, A. Kirsch, M. Heisel, A. A. Machado, D. Budjáš, E. Bellotti, V. Brudanin, Stefan Schönert, K. K. Guthikonda, Xianpeng Liu, Oliver Schulz, K. von Sturm, A. Domula, L. B. Bezrukov, H. Simgen, E. Shevchik, Alberto Pullia, Bayarto Lubsandorzhiev, Christian Bauer, I. R. Barabanov, K. Freund, A. Garfagnini, M. Junker, L. Ioannucci, Marcin Wójcik, S. V. Zhukov, G. Pessina, P. Grabmayr, V. Egorov, M. Allardt, R. Brugnera, A. Lubashevskiy, Luca Stanco, D. R. Zinatulina, Marc Walter, N. Frodyma, V. V. Kuzminov, J. Janicskó Csáthy, Matteo Agostini, Werner Hofmann, Cinzia Sada, Giovanni Benato, Claudio Gotti, M. Balata, C. Macolino, Mikael Hult, T. Bode, A. D. Ferella, B. Schwingenheuer, I. Zhitnikov, G. Heusser, K. T. Knöpfle, A. Hegai, G. Zuzel, O.I. Kochetov, W. Hampel, S. T. Belyaev, A. M. Gangapshev, E. V. Demidova, S. Belogurov, A. Wegmann, Igor Nemchenok, Bela Majorovits, M. Salathe, S. Nisi, Luciano Pandola, I. V. Kirpichnikov, A. A. Klimenko, N. Rumyantseva, B. Lehnert, O. Volynets, Ivano Lippi, K. N. Gusev, W. Maneschg, E. A. Yanovich, Stefano Riboldi, V. N. Kornoukhov, K. Pelczar, E. Andreotti, M. Misiaszek, M. Shirchenko, Laura Baudis, C. A. Ur, N. Barros, H. Y. Liao, Guillaume Lutter, A. Chernogorov, A. M. Bakalyarov, J. Jochum, F. Cossavella, M. Tarka, R. Falkenstein, C. Schmitt, C.M. O'Shaughnessy, A. Lazzaro, Matthias Laubenstein, P. Zavarise, Agostini, M, Allardt, M, Andreotti, E, Bakalyarov, A, Balata, M, Barabanov, I, Barnabé Heider, M, Barros, N, Baudis, L, Bauer, C, Becerici Schmidt, N, Bellotti, E, Belogurov, S, Belyaev, S, Benato, G, Bettini, A, Bezrukov, L, Bode, T, Brudanin, V, Brugnera, R, Budjáš, D, Caldwell, A, Cattadori, C, Chernogorov, A, Cossavella, F, Demidova, E, Domula, A, Egorov, V, Falkenstein, R, Ferella, A, Freund, K, Frodyma, N, Gangapshev, A, Garfagnini, A, Gotti, C, Grabmayr, P, Gurentsov, V, Gusev, K, Guthikonda, K, Hampel, W, Hegai, A, Heisel, M, Hemmer, S, Heusser, G, Hofmann, W, Hult, M, Inzhechik, L, Ioannucci, L, Janicskó Csáthy, J, Jochum, J, Junker, M, Kihm, T, Kirpichnikov, I, Kirsch, A, Klimenko, A, Knöpfle, K, Kochetov, O, Kornoukhov, V, Kuzminov, V, Laubenstein, M, Lazzaro, A, Lebedev, V, Lehnert, B, Liao, H, Lindner, M, Lippi, I, Liu, X, Lubashevskiy, A, Lubsandorzhiev, B, Lutter, G, Macolino, C, Machado, A, Majorovits, B, Maneschg, W, Misiaszek, M, Nemchenok, I, Nisi, S, O'Shaughnessy, C, Pandola, L, Pelczar, K, Pessina, G, Pullia, A, Riboldi, S, Rumyantseva, N, Sada, C, Salathe, M, Schmitt, C, Schreiner, J, Schulz, O, Schwingenheuer, B, Schönert, S, Shevchik, E, Shirchenko, M, Simgen, H, Smolnikov, A, Stanco, L, Strecker, H, Tarka, M, Ur, C, Vasenko, A, Volynets, O, von Sturm, K, Wagner, V, Walter, M, Wegmann, A, Wester, T, Wojcik, M, Yanovich, E, Zavarise, P, Zhitnikov, I, Zhukov, S, Zinatulina, D, Zuber, K, and Zuzel, G

Subjects
Physics, Particle physics, Physics - Instrumentation and Detectors, Physics and Astronomy (miscellaneous), Detector, Phase (waves), chemistry.chemical_element, FOS: Physical sciences, Germanium, Compton edge, Instrumentation and Detectors (physics.ins-det), Type (model theory), Shape parameter, chemistry, Beta (velocity), Sensitivity (control systems), Nuclear Experiment (nucl-ex), Engineering (miscellaneous), Nuclear Experiment
Abstract

The GERDA experiment located at the LNGS searches for neutrinoless double beta (0\nu\beta\beta) decay of ^{76}Ge using germanium diodes as source and detector. In Phase I of the experiment eight semi-coaxial and five BEGe type detectors have been deployed. The latter type is used in this field of research for the first time. All detectors are made from material with enriched ^{76}Ge fraction. The experimental sensitivity can be improved by analyzing the pulse shape of the detector signals with the aim to reject background events. This paper documents the algorithms developed before the data of Phase I were unblinded. The double escape peak (DEP) and Compton edge events of 2.615 MeV \gamma\ rays from ^{208}Tl decays as well as 2\nu\beta\beta\ decays of ^{76}Ge are used as proxies for 0\nu\beta\beta\ decay. For BEGe detectors the chosen selection is based on a single pulse shape parameter. It accepts 0.92$\pm$0.02 of signal-like events while about 80% of the background events at Q_{\beta\beta}=2039 keV are rejected. For semi-coaxial detectors three analyses are developed. The one based on an artificial neural network is used for the search of 0\nu\beta\beta\ decay. It retains 90% of DEP events and rejects about half of the events around Q_{\beta\beta}. The 2\nu\beta\beta\ events have an efficiency of 0.85\pm0.02 and the one for 0\nu\beta\beta\ decays is estimated to be 0.90^{+0.05}_{-0.09}. A second analysis uses a likelihood approach trained on Compton edge events. The third approach uses two pulse shape parameters. The latter two methods confirm the classification of the neural network since about 90% of the data events rejected by the neural network are also removed by both of them. In general, the selection efficiency extracted from DEP events agrees well with those determined from Compton edge events or from 2\nu\beta\beta\ decays., Comment: 18 pages, 27 figures

Published
2013

34. Results on Neutrinoless Double-βDecay ofGe76from Phase I of the GERDA Experiment

Author

Laura Baudis, J. Janicskó Csáthy, S. Hemmer, O.I. Kochetov, H. Y. Liao, I. Zhitnikov, M. Laubenstein, B. K. Lubsandorzhiev, C. Gotti, S. T. Belyaev, L. Stanco, A. M. Gangapshev, Hardy Simgen, A. D. Ferella, L. V. Inzhechik, V. G. Egorov, M. Balata, O. Schulz, X. Liu, A. Domula, K. T. Knoepfle, Ivano Lippi, V. I. Gurentsov, P. Zavarise, K. N. Gusev, M. Shirchenko, G. Zuzel, B. Lehnert, V. Wagner, D. R. Zinatulina, P. Grabmayr, O. Volynets, J. Jochum, A. A. Vasenko, N. Barros, T. Bode, A. Lubashevskiy, M. Allardt, V. I. Lebedev, C. O'Shaughnessy, N. Becerici-Schmidt, H. Strecker, C. Bauer, Stefano Riboldi, D. Budjáš, F. Potenza, Mikael Hult, V. B. Brudanin, C. Macolino, A. Garfagnini, S. Belogurov, M. Misiaszek, A. Kirsch, A. A. Machado, Manfred Lindner, T. Wester, A.A. Smolnikov, A. Lazzaro, E. Andreotti, C. Cattadori, Kai Zuber, E. Bellotti, C. Schmitt, N. Frodyma, W. Maneschg, A. Hegai, L. B. Bezrukov, G. Heusser, E. Shevchik, E. A. Yanovich, Stefano Nisi, M. Heider Barnabé, G. Pessina, R. Brugnera, Werner Hofmann, Alessandro Bettini, V. V. Kuzminov, Matteo Agostini, Allen Caldwell, L. Ioannucci, I. R. Barabanov, K. K. Guthikonda, K. von Sturm, S. V. Zhukov, M. Junker, M. M. Wojcik, K. Freund, B. Schwingenheuer, Stefan Schönert, A. Pullia, Cinzia Sada, Giovanni Benato, V. N. Kornoukhov, K. Pelczar, Guillaume Lutter, A. M. Bakalyarov, F. Cossavella, M. Tarka, R. Falkenstein, Jochen Schreiner, I. V. Kirpichnikov, C. A. Ur, A. Chernogorov, W. Hampel, E. V. Demidova, A. Wegmann, Igor Nemchenok, Bela Majorovits, M. Salathe, Th. Kihm, Luciano Pandola, A. A. Klimenko, M. Heisel, N. Rumyantseva, and M. Walter

Subjects
Physics, Nuclear physics, Double beta decay, Phase (matter), General Physics and Astronomy, Lepton number, Lower limit, Standard Model
Abstract

Neutrinoless double beta decay is a process that violates lepton number conservation. It is predicted to occur in extensions of the standard model of particle physics. This Letter reports the results from phase I of the Germanium Detector Array (GERDA) experiment at the Gran Sasso Laboratory (Italy) searching for neutrinoless double beta decay of the isotope $^{76}\mathrm{Ge}$. Data considered in the present analysis have been collected between November 2011 and May 2013 with a total exposure of 21.6 kg yr. A blind analysis is performed. The background index is about $1\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}2}\text{ }\text{ }\mathrm{counts}/(\mathrm{keV}\text{ }\mathrm{kg}\text{ }\mathrm{yr})$ after pulse shape discrimination. No signal is observed and a lower limit is derived for the half-life of neutrinoless double beta decay of $^{76}\mathrm{Ge}$, ${T}_{1/2}^{0\ensuremath{\nu}}g2.1\ifmmode\times\else\texttimes\fi{}{10}^{25}\text{ }\text{ }\mathrm{yr}$ (90% C.L.). The combination with the results from the previous experiments with $^{76}\mathrm{Ge}$ yields ${T}_{1/2}^{0\ensuremath{\nu}}g3.0\ifmmode\times\else\texttimes\fi{}{10}^{25}\text{ }\text{ }\mathrm{yr}$ (90% C.L.).

Published
2013
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35. Isotopically modified Ge detectors for GERDA: from production to operation

Author

Stefano Nisi, K. von Sturm, J. Janicskó Csáthy, A. Garfagnini, S. Georgi, G. Pivato, Mikael Hult, R. Falkenstein, P. Grabmayr, A. Lubashevskiy, S. Hemmer, C. Cattadori, M. Tarka, L. B. Bezrukov, S. Schönert, A. di Vacri, V. N. Kornoukhov, R. Brugnera, Matteo Agostini, Laura Baudis, A. Hegai, D. Budjáš, B. Lehnert, E. Bellotti, University of Zurich, and Grabmayr, P

Subjects
Physics, Physics - Instrumentation and Detectors, 530 Physics, 3105 Instrumentation, Detector, Phase (waves), FOS: Physical sciences, Order (ring theory), chemistry.chemical_element, Germanium, 10192 Physics Institute, Instrumentation and Detectors (physics.ins-det), Nuclear physics, chemistry, Yield (chemistry), Production (computer science), Sensitivity (control systems), Nuclear Experiment (nucl-ex), 2610 Mathematical Physics, Nuclear Experiment, Instrumentation, Mathematical Physics, Energy (signal processing)
Abstract

The \textsc{Gerda} experiment searches for the neutrinoless double beta ($0\nu\beta$beta$) decay of $^{76}$Ge using high-purity germanium detectors made of material enriched in $^{76}$Ge. For Phase II of the experiment a sensitivity for the half life $T_{1/2}^{0\nu}\,\,\sim2\cdot10^{26}$ yr is envisioned. Modified Broad Energy Germanium detectors (BEGe) with thick n$^+$ electrodes provide the capability to efficiently identify and reject background events, while keeping a large acceptance for the $0\nu\beta$beta$-decay signal through novel pulse-shape discrimination (PSD) techniques. The viability of producing thick-window BEGe-type detectors for the \textsc{Gerda} experiment is demonstrated by testing all the production steps from the procurement of isotopically modified germanium up to working BEGe detectors. Comprehensive testing of the spectroscopic as well as PSD performance of the \textsc{Gerda} Phase II prototype BEGe detectors proved that the properties of these detectors are identical to those produced previously from natural germanium material following the standard production line of the manufacturer. Furthermore, the production of BEGe detectors from a limited amount of isotopically modified germanium served to optimize the production, in order to maximize the overall detector mass yield. The results of this test campaign provided direct input for the subsequent production of the enriched germanium detectors., Comment: (16 pages, 5 figures)

Published
2013

36. 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
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37. Search of Neutrinoless Double Beta Decay with the GERDA Experiment

Author

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

Subjects
Semileptonic decay, Particle physics, Nuclear and High Energy Physics, enriched Ge, enriched Ge detectors, chemistry.chemical_element, Germanium, 01 natural sciences, 76Ge, Lower limit, neutrinoless double beta decay, Nuclear physics, T-1/2(0 nu), Double beta decay, 0103 physical sciences, 010306 general physics, detectors, Physics, Ge-76, T1/20ν, Enriched Ge detectors, Neutrinoless double beta decay, 010308 nuclear & particles physics, Semiconductor detector, MAJORANA, chemistry, Neutrino
Abstract

The GERDA (GERmanium Detector Array) is an experiment for the search of neutrinoless double beta decay ( 0 ν β β ) in 76Ge, located at Laboratori Nazionali del Gran Sasso of INFN (Italy). In the first phase of the experiment, a 90% confidence level (C.L.) sensitivity of 2.4 ⋅ 10 25 yr on the 0 ν β β decay half-life was achieved with a 21.6 kg⋅yr exposure and an unprecedented background index in the region of interest of 10−2 counts/(keV⋅kg⋅yr). No excess of signal events was found, and an experimental lower limit on the half-life of 2.1 ⋅ 1025 yr (90% C.L.) was established. Correspondingly, the limit on the effective Majorana neutrino mass is m e e 0.2 – 0.4 eV , depending on the considered nuclear matrix element. The previous claim for evidence of a 0 ν β β decay signal is strongly disfavored, and the field of research is open again.

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38. The Gerda experiment for the search of 0νββ decay in 76Ge

Author

M. Salathe, G. Heusser, K.-H. Ackermann, F. Cossavella, Francis Froborg, D. R. Zinatulina, M. Allardt, S. Vogt, Werner Hofmann, D. Lenz, Allen Caldwell, A. D`Andragora, P. Grabmayr, Mikael Hult, K. N. Gusev, M. Knapp, J. Kiko, U. Schwan, H. Seitz, S. Mayer, K. T. Knöpfle, K. K. Guthikonda, K. von Sturm, I. V. Kirpichnikov, A. Wegmann, M. M. Wojcik, A. Lubashevskiy, C. Bauer, Igor Nemchenok, B. Lehnert, A. Hegai, P. Peiffer, Kevin Kröninger, A. A. Machado, U. Trunk, R. Kankanyan, Stefano Riboldi, O. Volynets, Laura Baudis, V. I. Gurentsov, Bela Majorovits, M. Tarka, R. Falkenstein, Jochen Schreiner, L. Ioannucci, Josef Jochum, J. Oehm, O. Chkvorets, R. Brugnera, V. G. Egorov, M. Balata, M. Altmann, S. Hemmer, H. Y. Liao, C. Schmitt, P. Zavarise, W. Hampel, E. V. Demidova, Matteo Agostini, A. Domula, Bayarto Lubsandorzhiev, E. Bellotti, G. Zuzel, A. Chernogorov, J. Schubert, C. A. Ur, I. R. Barabanov, L. Niedermeier, S. V. Zhukov, V. B. Brudanin, L. B. Bezrukov, L. V. Inzhechik, V. N. Kornoukhov, K. Pelczar, S. Belogurov, C. Rossi Alvarez, Ivano Lippi, F. Stelzer, C. O'Shaughnessy, G. Marissens, E. Shevchik, N. Frodyma, N. Becerici-Schmidt, Hardy Simgen, M. Shirchenko, V. Kusminov, A. di Vacri, A. Lazzaro, A. D. Ferella, A. Kirsch, E. Andreotti, O.I. Kochetov, A. M. Bakalyarov, W. Maneschg, N. Barros, S. T. Belyaev, T. Bode, S. Schönert, Luca Stanco, E. A. Yanovich, Stefano Nisi, G. Meierhofer, A. M. Gangapshev, I. Zhitnikov, M. Junker, K. Freund, B. Schwingenheuer, Manfred Lindner, F. Ritter, A.A. Smolnikov, C. Cattadori, Kai Zuber, V. I. Lebedev, H. Strecker, D. Budjáš, S. Gazzana, O. Schulz, X. Liu, J. Gasparro, A. Denisov, M. Walter, Th. Kihm, Alessandro Bettini, M. Barnabe Heider, Luciano Pandola, A. A. Klimenko, A. Pullia, M. Heisel, S. Kianovsky, Matthias Laubenstein, Cinzia Sada, Jing Liu, Giovanni Benato, R. Gonzalez de Orduna, V. Wagner, A. A. Vasenko, A. Garfagnini, and J. Janicsko Csalty

Subjects
Physics, Physics and Astronomy (miscellaneous), hep-ex, 010308 nuclear & particles physics, Detector, nucl-ex, Nuclear & Particles Physics, 01 natural sciences, 7. Clean energy, Beta decay, GERmanium Detector Array, neutrinoless double beta decay, (0νββ), Nuclear physics, 0202 Atomic, Molecular, Nuclear, Particle And Plasma Physics, Double beta decay, 0103 physical sciences, Beta (velocity), 010306 general physics, physics.ins-det, 0206 Quantum Physics, Engineering (miscellaneous)
Abstract

The GERDA collaboration is performing a search for neutrinoless double beta decay of 76Ge with the eponymous detector. The experiment has been installed and commissioned at the Laboratori Nazionali del Gran Sasso and has started operation in November 2011. The design, construction and first operational results are described, along with detailed information from the R&D phase. peerReviewed

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39. The background in the $$0\nu \beta \beta $$ 0 ν β β experiment Gerda

Author

A. Domula, A. Garfagnini, M. Allardt, A. Chernogorov, M. Laubenstein, A. A. Machado, D. Budjáš, L. Stanco, I. V. Kirpichnikov, V. G. Egorov, M. Balata, S. Hemmer, P. Zavarise, Manfred Lindner, A. Kirsch, K. N. Gusev, C. A. Ur, A. Hegai, V. I. Lebedev, H. Strecker, V. Wagner, V.B. Brudanin, K. T. Knöpfle, Hardy Simgen, A. D. Ferella, F. Cossavella, A. A. Vasenko, D. Palioselitis, I. R. Barabanov, T. Bode, A. Wegmann, Igor Nemchenok, Bela Majorovits, C. Bauer, O. Schulz, X. Liu, M. Walter, S. V. Zhukov, Stefano Riboldi, G. Heusser, M. Salathe, A. Lubashevskiy, Alessandro Bettini, W. Maneschg, E. A. Yanovich, Stefano Nisi, Laura Baudis, D. R. Zinatulina, Marcin Wójcik, B. Lehnert, O. Volynets, J. Janicskó Csáthy, Josef Jochum, R. Brugnera, P. Grabmayr, N. Becerici-Schmidt, M. Tarka, V. V. Kuzminov, Matteo Agostini, M. Barnabe Heider, H. Y. Liao, V. N. Kornoukhov, K. Pelczar, V. I. Gurentsov, Mikael Hult, L. V. Inzhechik, W. Hampel, E. V. Demidova, I. Zhitnikov, Luciano Pandola, A. A. Klimenko, Werner Hofmann, T. Wester, Guillaume Lutter, M. Heisel, A. M. Bakalyarov, E. Andreotti, A.A. Smolnikov, Bayarto Lubsandorzhiev, C. Cattadori, Kai Zuber, K. Freund, Claudio Gotti, R. Falkenstein, B. Schwingenheuer, S. Belogurov, Jochen Schreiner, G. Zuzel, C. Schmitt, Ivano Lippi, M. Shirchenko, C. Macolino, N. Barros, M. Junker, Allen Caldwell, L. Ioannucci, C.M. O'Shaughnessy, K. K. Guthikonda, A. Lazzaro, K. von Sturm, S. Schönert, A. Pullia, Cinzia Sada, E. Bellotti, Giovanni Benato, Thomas Kihm, L. B. Bezrukov, E. Shevchik, G. Pessina, N. Frodyma, O.I. Kochetov, S. T. Belyaev, and A. M. Gangapshev

Subjects
Physics, Isotopes of germanium, Physics and Astronomy (miscellaneous), Physics::Instrumentation and Detectors, Astrophysics::Instrumentation and Methods for Astrophysics, Beta decay, Nuclear physics, Double beta decay, Beta (velocity), High Energy Physics::Experiment, Alpha decay, Decay chain, Nuclear Experiment, Engineering (miscellaneous), Energy (signal processing), Radioactive decay
Abstract

The GERmanium Detector Array (Gerda) experiment at the Gran Sasso underground laboratory (LNGS) of INFN is searching for neutrinoless double beta ( $$0\nu \beta \beta $$ ) decay of $$^{76}$$ Ge. The signature of the signal is a monoenergetic peak at 2039 keV, the $$Q_{\beta \beta }$$ value of the decay. To avoid bias in the signal search, the present analysis does not consider all those events, that fall in a 40 keV wide region centered around $$Q_{\beta \beta }$$ . The main parameters needed for the $$0\nu \beta \beta $$ analysis are described. A background model was developed to describe the observed energy spectrum. The model contains several contributions, that are expected on the basis of material screening or that are established by the observation of characteristic structures in the energy spectrum. The model predicts a flat energy spectrum for the blinding window around $$Q_{\beta \beta }$$ with a background index ranging from 17.6 to 23.8 $$\times $$ $$10^{-3}$$ cts/(keV kg yr). A part of the data not considered before has been used to test if the predictions of the background model are consistent. The observed number of events in this energy region is consistent with the background model. The background at $$Q_{\beta \beta }$$ is dominated by close sources, mainly due to $$^{42}$$ K, $$^{214}$$ Bi, $$^{228}$$ Th, $$^{60}$$ Co and $$\alpha $$ emitting isotopes from the $$^{226}$$ Ra decay chain. The individual fractions depend on the assumed locations of the contaminants. It is shown, that after removal of the known $$\gamma $$ peaks, the energy spectrum can be fitted in an energy range of 200 keV around $$Q_{\beta \beta }$$ with a constant background. This gives a background index consistent with the full model and uncertainties of the same size.

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40. Upgrade of the GERDA experiment

Author

M. Shirchenko, C. Gotti, V. I. Gurentsov, V. Egorov, N. Barros, Allen Caldwell, L. Ioannucci, A. Domula, L. V. Inzhechik, T. Bode, Matthias Laubenstein, M. Allardt, O.I. Kochetov, P. Zavarise, S. T. Belyaev, A. M. Gangapshev, V. Wagner, BayarJon Paul Lubsandorzhiev, V. Kazalov, A. A. Vasenko, K. Pelczar, N. Frodyma, C. Bauer, I. Zhitnikov, Stefano Riboldi, D. Borowicz, P. Grabmayr, J. Jochum, Guillaume Lutter, M. Misiaszek, A. M. Bakalyarov, K. von Sturm, A. Garfagnini, S. Hemmer, M. Junker, J. Janicsko, M. M. Wojcik, A. Pullia, Ivano Lippi, S. Schönert, L. Stanco, G. Heusser, Cinzia Sada, Giovanni Benato, A. Kirsch, W. Maneschg, E. A. Yanovich, Stefano Nisi, A. Wegmann, Hardy Simgen, A. Lubashevskiy, Werner Hofmann, B. Lehnert, Igor Nemchenok, M. Balata, R. Falkenstein, Jochen Schreiner, Bela Majorovits, K. Freund, B. Schwingenheuer, V. I. Lebedev, A. Chernogorov, H. Strecker, G. Zuzel, I. V. Kirpichnikov, M. Salathe, A. Hegai, M. Walter, D. R. Zinatulina, Mikael Hult, C. A. Ur, Th. Kihm, W. Hampel, E. V. Demidova, Luciano Pandola, A. A. Klimenko, M. Heisel, N. Rumyantseva, C. Schmitt, C. Cattadori, D. Palioselitis, O. Schulz, K. T. Knoepfle, K. N. Gusev, V.N. Kornoukhov, S. Belogurov, Manfred Lindner, T. Wester, E. Bellotti, A.A. Smolnikov, A. Lazzaro, R. Brugnera, V. V. Kuzminov, Kai Zuber, Matteo Agostini, V. Brudanin, I. R. Barabanov, S. V. Zhukov, D. Budjáš, C. Macolino, Alessandro Bettini, N. Becerici-Schmidt, Laura Baudis, H. Wilsenach, Gerd Marissens, H. Y. Liao, L. B. Bezrukov, E. Shevchik, and G. Pessina

Subjects
Engineering, Upgrade, business.industry, Electrical engineering, Systems engineering, business

41. 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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42. 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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43. 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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44. 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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45. 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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46. 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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47. A Compton scattering setup for pulse shape discrimination studies in germanium detectors.

Author

von Sturm K, Belogurov S, Brugnera R, Garfagnini A, Lippi I, Modenese L, Rosso D, and Turcato M

Abstract

Pulse shape discrimination is an important handle to improve sensitivity in low background experiments. A dedicated setup was built to investigate the response of high-purity germanium detectors to single Compton scattered events. Using properly collimated γ-ray sources, it is possible to select events with known interaction location. The aim is to correlate the position dependent signal shape with geometrical and electrical properties of the detector. We report on design and performance of the setup with a first look on data., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Published
2017
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48. Results on neutrinoless double-β decay of 76Ge from phase I of the GERDA experiment.

Author

Agostini M, Allardt M, Andreotti E, Bakalyarov AM, Balata M, Barabanov I, Barnabé Heider M, Barros N, Baudis L, Bauer C, Becerici-Schmidt N, Bellotti E, Belogurov S, Belyaev ST, Benato G, Bettini A, Bezrukov L, Bode T, Brudanin V, Brugnera R, Budjáš D, Caldwell A, Cattadori C, Chernogorov A, Cossavella F, Demidova EV, Domula A, Egorov V, Falkenstein R, Ferella A, Freund K, Frodyma N, Gangapshev A, Garfagnini A, Gotti C, Grabmayr P, Gurentsov V, Gusev K, Guthikonda KK, Hampel W, Hegai A, Heisel M, Hemmer S, Heusser G, Hofmann W, Hult M, Inzhechik LV, Ioannucci L, Janicskó Csáthy J, Jochum J, Junker M, Kihm T, Kirpichnikov IV, Kirsch A, Klimenko A, Knöpfle KT, Kochetov O, Kornoukhov VN, Kuzminov VV, Laubenstein M, Lazzaro A, Lebedev VI, Lehnert B, Liao HY, Lindner M, Lippi I, Liu X, Lubashevskiy A, Lubsandorzhiev B, Lutter G, Macolino C, Machado AA, Majorovits B, Maneschg W, Misiaszek M, Nemchenok I, Nisi S, O'Shaughnessy C, Pandola L, Pelczar K, Pessina G, Pullia A, Riboldi S, Rumyantseva N, Sada C, Salathe M, Schmitt C, Schreiner J, Schulz O, Schwingenheuer B, Schönert S, Shevchik E, Shirchenko M, Simgen H, Smolnikov A, Stanco L, Strecker H, Tarka M, Ur CA, Vasenko AA, Volynets O, von Sturm K, Wagner V, Walter M, Wegmann A, Wester T, Wojcik M, Yanovich E, Zavarise P, Zhitnikov I, Zhukov SV, Zinatulina D, Zuber K, and Zuzel G

Abstract

Neutrinoless double beta decay is a process that violates lepton number conservation. It is predicted to occur in extensions of the standard model of particle physics. This Letter reports the results from phase I of the Germanium Detector Array (GERDA) experiment at the Gran Sasso Laboratory (Italy) searching for neutrinoless double beta decay of the isotope (76)Ge. Data considered in the present analysis have been collected between November 2011 and May 2013 with a total exposure of 21.6 kg yr. A blind analysis is performed. The background index is about 1 × 10(-2) counts/(keV kg yr) after pulse shape discrimination. No signal is observed and a lower limit is derived for the half-life of neutrinoless double beta decay of (76)Ge, T(1/2)(0ν) >2.1 × 10(25) yr (90% C.L.). The combination with the results from the previous experiments with (76)Ge yields T(1/2)(0ν)>3.0 × 10(25) yr (90% C.L.).

Published
2013
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