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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. 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

9. 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

10. 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

11. 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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12. LEGEND $^{\bf 76}$Ge Detectors: Production, Characterization, and Performance

Author

A. Reine, R. Brugnera, J. F. Wilkerson, T. Comellato, Bjoern Lehnert, L. Hauertmann, J. Detwiler, D. Radford, A. Poon, A. Alexander, T. Mathew, C. Gooch, M. Clark, G. Othman, I. Guinn, X. Liu, C.-A. Christofferson, K. Gusev, O. Schulz, J. Thompson, C. Wiseman, A. Engelhardt, V. Biancacci, S. Mertens, I. Abt, T. Caldwell, Y. Kermaidic, M. Hult, G. Lutter, M. Busch, L. Pertoldi, P. Barton, K. Warnello, A. Garfagnini, R. Martin, F. Edzards, A. Zschocke, G. Marissens, J. Gruszko, B. Bos, and S. Schoenert

Subjects
Physics::Instrumentation and Detectors, High Energy Physics::Experiment
Abstract

LEGEND searches for lepton number violation in neutrinoless double beta (0νββ) decay using $^{76}$Ge-enriched high-purity germanium (HPGe) detectors immersed in liquid argon. The first stage, LEGEND-200, will operate 200 kg of detectors, a significant fraction of which are the new large Inverted Coaxial Point Contact (ICPC) detectors currently under production. An extensive characterization campaign to determine the basic operational parameters of the newly produced detectors is performed in vacuum cryostats at two underground sites in order to reduce the internal creation of cosmogenic radionuclides. Other dedicated scanning setups are used to obtain a detailed understanding of alpha and beta surface events on the p+ and n+ contacts which are projected to be the dominant backgrounds for the 0νββ decay search. This poster will present the production experience of the new ICPC detectors, the ongoing characterization campaigns, and the projected detector performances based on recent measurements.

Published
2020
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13. Dynamic mechanical characterization of two-photon-polymerized SZ2080 photoresist

Author

Claudia Comi, Roberto Osellame, Valentina Zega, and L. Pertoldi

Subjects
010302 applied physics, Fabrication, Materials science, mechanical charaterization, Two-photon polymerization, General Physics and Astronomy, Metamaterial, Nanotechnology, 02 engineering and technology, Photoresist, 021001 nanoscience & nanotechnology, Laser, Microstructure, 01 natural sciences, law.invention, Characterization (materials science), law, 0103 physical sciences, Femtosecond, 0210 nano-technology, Material properties, polymers
Abstract

Two-photon polymerization (2PP) is a material processing technique employed for the production of high-resolution microstructures. The high potential of this technique in the fabrication of structured materials, or metamaterials, has recently attracted significant research interest. To proceed toward real applications, the mechanical properties of the material obtained by 2PP should be known. These properties depend on all the process parameters, which affect the cross-linking between the polymeric chains, and very few results are available in the literature. In this work, we perform a systematic characterization of the elastic properties of femtosecond laser-polymerized SZ2080 (hybrid organic-inorganic photoresist) by combining dynamic experimental tests and numerical simulations on properly designed microstructures. Studying the resonance frequencies of micro-cantilevers, we demonstrate the possibility of tailoring the mechanical properties of the material by changing the laser irradiation conditions. This result paves the way to the use of 2PP for the fabrication of microdevices operating in a dynamic regime with optimized material properties.

Published
2020
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14. The cosmic muon-induced background for the LEGEND-1000 alternative site at LNGS

Author

M Neuberger, L. Pertoldi, S Schönert, and C. Wiesinger

Subjects
History, Computer Science Applications, Education
Abstract

The in-situ production of long-lived radio-isotopes by cosmic muon interactions may generate a non-negligible background for rare event searches in the deep subsurface. The delayed decay of 77(m)Ge has been identified as the dominant in-situ cosmogenic contributor for a neutrinoless double-beta decay search with 76Ge. The future ton-scale LEGEND-1000 experiment requires a total background of ≤ 10−5 cts/(keV-kg-yr). Dedicated Monte Carlo studies of the 77(m)Ge background at the alternative LNGS site were performed. The addition of passive neutron moderators, in combination with a delayed coincidence strategy, results in a background contribution of 8.6 × 10−7 cts/(keV.kg.yr) with an additional dead time of < 9%.

Published
2021
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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. 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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18. Searches for new physics below twice the electron mass with GERDA.

Author

Agostini M, Alexander A, Araujo G, Bakalyarov AM, Balata M, Barabanov I, Baudis L, Bauer C, Belogurov S, Bettini A, Bezrukov L, Biancacci V, Bossio E, Bothe V, Brugnera R, Caldwell A, Calgaro S, Cattadori C, Chernogorov A, Chiu PJ, Comellato T, D'Andrea V, Demidova EV, Marco ND, Doroshkevich E, Fomina M, Gangapshev A, Garfagnini A, Gooch C, Grabmayr P, Gurentsov V, Gusev K, Hakenmüller J, Hemmer S, Hofmann W, Huang J, Hult M, Inzhechik LV, Csáthy JJ, Jochum J, Junker M, Kazalov V, Kermaïdic Y, Khushbakht H, Kihm T, Kilgus K, Kirpichnikov IV, Klimenko A, Knöpfle KT, Kochetov O, Kornoukhov VN, Krause P, Kuzminov VV, Laubenstein M, Lindner M, Lippi I, Lubashevskiy A, Lubsandorzhiev B, Lutter G, Macolino C, Majorovits B, Maneschg W, Marshall G, 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, 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, Sturm KV, Wester T, Wiesinger C, Wojcik M, Yanovich E, Zatschler B, Zhitnikov I, Zhukov SV, Zinatulina D, Zschocke A, Zuber K, and Zuzel G

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 α ' / α < 8.7 × 10 - 24 and g ae < 3.3 × 10 - 12 at 90% credible interval (CI), respectively. Additionally, a search for peak-like signals from beyond the Standard Model decays of nucleons and electrons is performed. We find for the inclusive decay of a single neutron in 76 Ge a lower lifetime limit of τ n > 1.5 × 10 24 years and for a proton τ p > 1.3 × 10 24 years at 90% CI. For the electron decay e - → ν e γ a lower limit of τ e > 5.4 × 10 25 years at 90% CI has been determined., Supplementary Information: The online version contains supplementary material available at 10.1140/epjc/s10052-024-13020-0., (© The Author(s) 2024.)

Published
2024
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19. 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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20. Liquid argon light collection and veto modeling in GERDA Phase II.

Author

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

Abstract

The ability to detect liquid argon scintillation light from within a densely packed high-purity germanium detector array allowed the Gerda experiment to reach an exceptionally low background rate in the search for neutrinoless double beta decay of 76 Ge. Proper modeling of the light propagation throughout the experimental setup, from any origin in the liquid argon volume to its eventual detection by the novel light read-out system, provides insight into the rejection capability and is a necessary ingredient to obtain robust background predictions. In this paper, we present a model of the Gerda liquid argon veto, as obtained by Monte Carlo simulations and constrained by calibration data, and highlight its application for background decomposition., (© The Author(s) 2023.)

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

Author

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

Abstract

We search for tri-nucleon decays of 76 Ge in the dataset from the GERmanium Detector Array (GERDA) experiment. Decays that populate excited levels of the daughter nucleus above the threshold for particle emission lead to disintegration and are not considered. The ppp-, ppn-, and pnn-decays lead to 73 Cu, 73 Zn, and 73 Ga nuclei, respectively. These nuclei are unstable and eventually proceed by the beta decay of 73 Ga to 73 Ge (stable). We search for the 73 Ga decay exploiting the fact that it dominantly populates the 66.7 keV 73 m Ga state with half-life of 0.5 s. The nnn-decays of 76 Ge that proceed via 73 m Ge are also included in our analysis. We find no signal candidate and place a limit on the sum of the decay widths of the inclusive tri-nucleon decays that corresponds to a lower lifetime limit of 1.2 × 10 26  yr  (90% credible interval). This result improves previous limits for tri-nucleon decays by one to three orders of magnitude., (© The Author(s) 2023.)

Published
2023
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22. 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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23. Pulse shape analysis in Gerda Phase II.

Author

Agostini M, Araujo G, Bakalyarov AM, Balata M, Barabanov I, Baudis L, Bauer C, Bellotti E, Belogurov S, Bettini A, Bezrukov L, Biancacci V, Bossio E, Bothe V, Brudanin V, Brugnera R, Caldwell A, Cattadori C, Chernogorov A, Comellato T, D'Andrea V, Demidova EV, Marco ND, Doroshkevich E, Fischer F, Fomina M, Gangapshev A, Garfagnini A, Gooch C, Grabmayr P, Gurentsov V, Gusev K, Hakenmüller J, Hemmer S, Hiller R, Hofmann W, Huang J, Hult M, Inzhechik LV, Csáthy JJ, Jochum J, Junker M, Kazalov V, Kermaïdic Y, Khushbakht H, Kihm T, Kilgus K, Kirsch A, Kirpichnikov IV, Klimenko A, Knöpfle KT, Kochetov O, Kornoukhov VN, Krause P, Kuzminov VV, Laubenstein M, Lazzaro A, Lindner M, Lippi I, Lubashevskiy A, Lubsandorzhiev B, Lutter G, Macolino C, Majorovits B, Maneschg W, Manzanillas L, Miloradovic M, Mingazheva R, Misiaszek M, Müller Y, Nemchenok I, Panas K, Pandola L, Pelczar K, Pertoldi L, Piseri P, Pullia A, Ransom C, Rauscher L, Redchuk M, Riboldi S, Rumyantseva N, Sada C, Salamida F, Schönert S, Schreiner J, Schütt M, Schütz AK, Schulz O, Schwarz M, Schwingenheuer B, Selivanenko O, Shevchik E, Shirchenko M, Shtembari L, Simgen H, Smolnikov A, Stukov D, Vasenko AA, Veresnikova A, Vignoli C, Sturm KV, Wagner V, Wester T, Wiesinger C, Wojcik M, Yanovich E, Zatschler B, Zhitnikov I, Zhukov SV, Zinatulina D, Zschocke A, Zsigmond AJ, Zuber K, and Zuzel G

Abstract

The GERmanium Detector Array (Gerda) collaboration searched for neutrinoless double- β decay in 76 Ge using isotopically enriched high purity germanium detectors at the Laboratori Nazionali del Gran Sasso of INFN. After Phase I (2011-2013), the experiment benefited from several upgrades, including an additional active veto based on LAr instrumentation and a significant increase of mass by point-contact germanium detectors that improved the half-life sensitivity of Phase II (2015-2019) by an order of magnitude. At the core of the background mitigation strategy, the analysis of the time profile of individual pulses provides a powerful topological discrimination of signal-like and background-like events. Data from regular 228 Th calibrations and physics data were both considered in the evaluation of the pulse shape discrimination performance. In this work, we describe the various methods applied to the data collected in Gerda Phase II corresponding to an exposure of 103.7 kg year. These methods suppress the background by a factor of about 5 in the region of interest around Q β β = 2039  keV, while preserving ( 81 ± 3 ) % of the signal. In addition, an exhaustive list of parameters is provided which were used in the final data analysis., (© The Author(s) 2022.)

Published
2022
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24. Calibration of the Gerda experiment.

Author

Agostini M, Araujo G, Bakalyarov AM, Balata M, Barabanov I, Baudis L, Bauer C, Bellotti E, Belogurov S, Bettini A, Bezrukov L, Biancacci V, Bossio E, Bothe V, Brudanin V, Brugnera R, Caldwell A, Cattadori C, Chernogorov A, Comellato T, D'Andrea V, Demidova EV, Marco ND, Doroshkevich E, Fischer F, Fomina M, Gangapshev A, Garfagnini A, Gooch C, Grabmayr P, Gurentsov V, Gusev K, Hakenmüller J, Hemmer S, Hiller R, Hofmann W, Huang J, Hult M, Inzhechik LV, Csáthy JJ, Jochum J, Junker M, Kazalov V, Kermaïdic Y, Khushbakht H, Kihm T, Kirpichnikov IV, Klimenko A, Kneißl R, Knöpfle KT, Kochetov O, Kornoukhov VN, Krause P, Kuzminov VV, Laubenstein M, Lindner M, Lippi I, Lubashevskiy A, Lubsandorzhiev B, Lutter G, Macolino C, Majorovits B, Maneschg W, Manzanillas L, Miloradovic M, Mingazheva R, Misiaszek M, Moseev P, Müller Y, Nemchenok I, Pandola L, Pelczar K, Pertoldi L, Piseri P, Pullia A, Ransom C, Rauscher L, Riboldi S, Rumyantseva N, Sada C, Salamida F, Schönert S, Schreiner J, Schütt M, Schütz AK, Schulz O, Schwarz M, Schwingenheuer B, Selivanenko O, Shevchik E, Shirchenko M, Shtembari L, Simgen H, Smolnikov A, Stukov D, Vasenko AA, Veresnikova A, Vignoli C, von Sturm K, Wester T, Wiesinger C, Wojcik M, Yanovich E, Zatschler B, Zhitnikov I, Zhukov SV, Zinatulina D, Zschocke A, Zsigmond AJ, Zuber K, and Zuzel G

Abstract

The GERmanium Detector Array (Gerda) collaboration searched for neutrinoless double- β decay in 76 Ge with an array of about 40 high-purity isotopically-enriched germanium detectors. The experimental signature of the decay is a monoenergetic signal at Q β β = 2039.061 ( 7 )  keV in the measured summed energy spectrum of the two emitted electrons. Both the energy reconstruction and resolution of the germanium detectors are crucial to separate a potential signal from various backgrounds, such as neutrino-accompanied double- β decays allowed by the Standard Model. The energy resolution and stability were determined and monitored as a function of time using data from regular 228 Th calibrations. In this work, we describe the calibration process and associated data analysis of the full Gerda dataset, tailored to preserve the excellent resolution of the individual germanium detectors when combining data over several years., (© The Author(s) 2021.)

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

Author

Agostini M, Araujo G, Bakalyarov AM, Balata M, Barabanov I, Baudis L, Bauer C, Bellotti E, Belogurov S, Bettini A, Bezrukov L, Biancacci V, Bossio E, Bothe V, Brudanin V, Brugnera R, Caldwell A, Cattadori C, Chernogorov A, Comellato T, D'Andrea V, Demidova EV, Marco ND, Doroshkevich E, Fischer F, Fomina M, Gangapshev A, Garfagnini A, Gooch C, Grabmayr P, Gurentsov V, Gusev K, Hakenmüller J, Hemmer S, Hofmann W, Huang J, Hult M, Inzhechik LV, Janicskó Csáthy J, Jochum J, Junker M, Kazalov V, Kermaïdic Y, Khushbakht H, Kihm T, Kirpichnikov IV, Klimenko A, Kneißl R, Knöpfle KT, Kochetov O, Kornoukhov VN, Krause P, Kuzminov VV, Laubenstein M, Lindner M, Lippi I, Lubashevskiy A, Lubsandorzhiev B, Lutter G, Macolino C, Majorovits B, Maneschg W, Manzanillas L, Miloradovic M, Mingazheva R, Misiaszek M, Moseev P, Müller Y, Nemchenok I, Pandola L, Pelczar K, Pertoldi L, Piseri P, Pullia A, Ransom C, Rauscher L, Riboldi S, Rumyantseva N, Sada C, Salamida F, Schönert S, Schreiner J, Schütt M, Schütz AK, Schulz O, Schwarz M, Schwingenheuer B, Selivanenko O, Shevchik E, Shirchenko M, Shtembari L, Simgen H, Smolnikov A, Stukov D, Vasenko AA, Veresnikova A, Vignoli C, von Sturm K, Wester T, Wiesinger C, Wojcik M, Yanovich E, Zatschler B, Zhitnikov I, Zhukov SV, Zinatulina D, Zschocke A, Zsigmond AJ, Zuber K, and Zuzel G

Abstract

Neutrinoless double- β decay of 76 Ge is searched for with germanium detectors where source and detector of the decay are identical. For the success of future experiments it is important to increase the mass of the detectors. We report here on the characterization and testing of five prototype detectors manufactured in inverted coaxial (IC) geometry from material enriched to 88% in 76 Ge. IC detectors combine the large mass of the traditional semi-coaxial Ge detectors with the superior resolution and pulse shape discrimination power of point contact detectors which exhibited so far much lower mass. Their performance has been found to be satisfactory both when operated in vacuum cryostat and bare in liquid argon within the Gerda setup. The measured resolutions at the Q -value for double- β decay of 76 Ge ( Q β β  = 2039 keV) are about 2.1 keV full width at half maximum in vacuum cryostat. After 18 months of operation within the ultra-low background environment of the GERmanium Detector Array (Gerda) experiment and an accumulated exposure of 8.5 kg · year, the background index after analysis cuts is measured to be 4 . 9 - 3.4 + 7.3 × 10 - 4 counts / ( keV · kg · year ) around Q β β . This work confirms the feasibility of IC detectors for the next-generation experiment Legend., (© The Author(s) 2021.)

Published
2021
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26. 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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27. 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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28. 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 years (90% C.L.). Our 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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29. 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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