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

Author: GERDA Collaboration, Agostini, M., Alexander, A., Araujo, G. R., Bakalyarov, A. M., Balata, M., Barabanov, I., Baudis, L., Bauer, C., Belogurov, S., Bettini, A., Bezrukov, L., Biancacci, V., Bossio, E., Bothe, V., Brugnera, R., Caldwell, A., Calgaro, S., Cattadori, C., Chernogorov, A., Chiu, P. -J., Comellato, T., D'Andrea, V., Demidova, E. V., Di Marco, N., 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, L. V., Csáthy, J. Janicskó, Jochum, J., Junker, M., Kazalov, V., Kermaïdic, Y., Khushbakht, H., Kihm, T., Kilgus, K., Kirpichnikov, I. V., Klimenko, A., Knöpfle, K. T., Kochetov, O., Kornoukhov, V. N., Krause, P., Kuzminov, V. V., Laubenstein, M., Lindner, M., Lippi, I., Lubashevskiy, A., Lubsandorzhiev, B., Lutter, G., Macolino, C., Majorovits, B., Maneschg, W., 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, A-K., Schulz, O., Schwarz, M., Schwingenheuer, B., Selivanenko, O., Shevchik, E., Shirchenko, M., Shtembari, L., Simgen, H., Smolnikov, A., Stukov, D., Sullivan, S., Vasenko, A. A., Veresnikova, A., Vignoli, C., von Sturm, K., Wester, T., Wiesinger, C., Wojcik, M., Yanovich, E., Zatschler, B., Zhitnikov, I., Zhukov, S. V., Zinatulina, D., Zschocke, A., Zuber, K., and Zuzel, G.
Subjects: Nuclear Experiment, High Energy Physics - Experiment
Abstract: A search for full energy depositions from bosonic keV-scale dark matter candidates of masses between 65 keV 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 yr, 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 $\alpha$'/$\alpha$ < 8.7x10$^{-24}$ and g$_{ae}$ < 3.3x10$^{-12}$ 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 $\tau_n$ > 1.5x10$^{24}$ yr and for a proton $\tau_p$ > 1.3x10$^{24}$ yr at 90% CI. For the electron decay e$^-\rightarrow\nu_e\gamma$ a lower limit of $\tau_e$ > 5.4x10$^{25}$ yr at 90% CI has been determined., Comment: 20 pages, 12 figures, 7 tables
Published: 2024

2. An improved limit on the neutrinoless double-electron capture of $^{36}$Ar with GERDA

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

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

Author: Agostini, M., Alexander, A., Araujo, G., Bakalyarov, A. M., Balata, M., Barabanov, I., Baudis, L., Bauer, C., Belogurov, S., Bettini, A., Bezrukov, L., Biancacci, V., Bossio, E., Bothe, V., Brugnera, R., Caldwell, A., Calgaro, S., Cattadori, C., Chernogorov, A., Chiu, P.-J., Comellato, T., D’Andrea, V., Demidova, E. V., Marco, N. Di, 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, L. V., Csáthy, J. Janicskó, Jochum, J., Junker, M., Kazalov, V., Kermaïdic, Y., Khushbakht, H., Kihm, T., Kilgus, K., Kirpichnikov, I. V., Klimenko, A., Knöpfle, K. T., Kochetov, O., Kornoukhov, V. N., Krause, P., Kuzminov, V. V., Laubenstein, M., Lindner, M., Lippi, I., Lubashevskiy, A., Lubsandorzhiev, B., Lutter, G., Macolino, C., Majorovits, B., Maneschg, W., 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, A-K., Schulz, O., Schwarz, M., Schwingenheuer, B., Selivanenko, O., Shevchik, E., Shirchenko, M., Shtembari, L., Simgen, H., Smolnikov, A., Stukov, D., Sullivan, S., Vasenko, A. A., Veresnikova, A., Vignoli, C., Sturm, K. von, Wester, T., Wiesinger, C., Wojcik, M., Yanovich, E., Zatschler, B., Zhitnikov, I., Zhukov, S. V., Zinatulina, D., Zschocke, A., Zuber, K., and Zuzel, G.
Published: 2024
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4. Final Results of GERDA on the Two-Neutrino Double-$\beta$ Decay Half-Life of $^{76}$Ge

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

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

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

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

8. Pulse shape analysis in GERDA Phase II

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

Author: Knöpfle, K. T. and Schwingenheuer, B.
Subjects: Physics - Instrumentation and Detectors, Nuclear Experiment
Abstract: In searching for the neutrinoless double-beta decay of $^{76}$Ge the GERmanium Detector Array (GERDA) experiment at the INFN Laboratori Nazionali del Gran Sasso has achieved an unprecedented low background of well below 10$^{-3}$ cts/(keV$\cdot$kg$\cdot$yr) in the region of interest. It has taken advantage of the first realization of a novel shielding concept based on a large cryostat filled with a liquid noble gas that is immersed in a water tank. The germanium detectors are operated without encapsulation in liquid argon. Argon and water shield the environmental background from the laboratory and the cryostat construction materials to a negligible level. The same approach has been adopted in the meantime by various experiments. This paper provides an overview of the design and operating experience of the 64 m$^3$ liquid argon cryostat and its associated infrastructure. The discussion includes the challenging safety issues associated with the operation of a large cryostat in a water tank., Comment: 33 pages, 13 figures, 8 tables
Published: 2022
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10. LEGEND-1000 Preconceptual Design Report

Author: LEGEND Collaboration, Abgrall, N., Abt, I., Agostini, M., Alexander, A., Andreoiu, C., Araujo, G. R., Avignone III, F. T., Bae, W., Bakalyarov, A., Balata, M., Bantel, M., Barabanov, I., Barabash, A. S., Barbeau, P. S., Barton, C. J., Barton, P. J., Baudis, L., Bauer, C., Bernieri, E., Bezrukov, L., Bhimani, K. H., Biancacci, V., Blalock, E., Bolozdynya, A., Borden, S., Bos, B., Bossio, E., Boston, A., Bothe, V., Bouabid, R., Boyd, S., Brugnera, R., Burlac, N., Busch, M., Caldwell, A., Caldwell, T. S., Carney, R., Cattadori, C., Chan, Y. -D., Chernogorov, A., Christofferson, C. D., Chu, P. -H., Clark, M., Cohen, T., Combs, D., Comellato, T., Cooper, R. J., Costa, I. A., D'Andrea, V., Detwiler, J. A., Di Giacinto, A., Di Marco, N., Dobson, J., Drobizhev, A., Durand, M. R., Edzards, F., Efremenko, Yu., Elliott, S. R., Engelhardt, A., Fajt, L., Faud, N., Febbraro, M. T., Ferella, F., Fields, D. E., Fischer, F., Fomina, M., Fox, H., Franchi, J., Gala, R., Galindo-Uribarri, A., Gangapshev, A., Garfagnini, A., Geraci, A., Gilbert, C., Gold, M., Gooch, C., Gradwohl, K. P., Green, M. P., Grinyer, G. F., Grobov, A., Gruszko, J., Guinn, I., Guiseppe, V. E., Gurentsov, V., Gurov, Y., Gusev, K., Hacket, B., Hagemann, F., Hakenmüeller, J., Haranczyk, M., Hauertmann, L., Haufe, C. R., Hayward, C., Heffron, B., Henkes, F., Henning, R., Aguilar, D. Hervas, Hinton, J., Hodak, R., Hoffmann, H., Hofmann, W., Hostiuc, A., Huang, J., Hult, M., Mirza, M. Ibrahim, Jochum, J., Jones, R., Judson, D., Junker, M., Kaizer, J., Kazalov, V., Kermaïdic, Y., Khushbakht, H., Kidd, M., Kihm, T., Kilgus, K., Kim, I., Klimenko, A., Knöpfle, K. T., Kochetov, O., Konovalov, S. I., Kontul, I., Kool, K., Kormos, L. L., Kornoukhov, V. N., Korosec, M., Krause, P., Kuzminov, V. V., López-Castaño, J. M., Lang, K., Laubenstein, M., León, E., Lehnert, B., Leonhardt, A., Li, A., Lindner, M., Lippi, I., Liu, X., Liu, J., Loomba, D., Lubashevskiy, A., Lubsandorzhiev, B., Lusardi, N., Müller, Y., Macko, M., Macolino, C., Majorovits, B., Mamedov, F., Maneschg, W., Manzanillas, L., Marshall, G., Martin, R. D., Martin, E. L., Massarczyk, R., Mei, D., Meijer, S. J., Mertens, S., Misiaszek, M., Mondragon, E., Morella, M., Morgan, B., Mroz, T., Muenstermann, D., Nave, C. J., Nemchenok, I., Neuberger, M., Oli, T. K., Gann, G. Orebi, Othman, G., Palušova, V., Panth, R., Papp, L., Paudel, L. S., Pelczar, K., Perez, J. Perez, Pertoldi, L., Pettus, W., Piseri, P., Poon, A. W. P., Povinec, P., Pullia, A., Radford, D. C., Ramachers, Y. A., Ransom, C., Rauscher, L., Redchuk, M., Reine, A. L., Riboldi, S., Rielage, K., Rozov, S., Rukhadze, E., Rumyantseva, N., Runge, J., Ruof, N. W., Saakyan, R., Sailer, S., Salamanna, G., Salamida, F., Salvat, D. J., Sandukovsky, V., Schönert, S., Schültz, A., Schütt, M., Schaper, D. C., Schreiner, J., Schulz, O., Schuster, M., Schwarz, M., Schwingenheuer, B., Selivanenko, O., Shafiee, M., Shevchik, E., Shirchenko, M., Shitov, Y., Simgen, H., Simkovic, F., Skorokhvatov, M., Slavickova, M., Smolek, K., Smolnikov, A., Solomon, J. A., Song, G., Starosta, K., Stekl, I., Stommel, M., Stukov, D., Sumathi, R. R., Sweigart, D. A., Szczepaniec, K., Taffarello, L., Tagnani, D., Tayloe, R., Tedeschi, D., Turqueti, M., Varner, R. L., Vasilyev, S., Veresnikova, A., Vetter, K., Vignoli, C., Vogl, C., von Sturm, K., Waters, D., Waters, J. C., Wei, W., Wiesinger, C., Wilkerson, J. F., Willers, M., Wiseman, C., Wojcik, M., Wu, V. H. -S., Xu, W., Yakushev, E., Ye, T., Yu, C. -H., Yumatov, V., Zaretski, N., Zeman, J., Zhitnikov, I., Zinatulina, D., Zschocke, A. -K., Zsigmond, A. J., Zuber, K., and Zuzel, G.
Subjects: Physics - Instrumentation and Detectors, Nuclear Experiment
Abstract: We propose the construction of LEGEND-1000, the ton-scale Large Enriched Germanium Experiment for Neutrinoless $\beta \beta$ Decay. This international experiment is designed to answer one of the highest priority questions in fundamental physics. It consists of 1000 kg of Ge detectors enriched to more than 90% in the $^{76}$Ge isotope operated in a liquid argon active shield at a deep underground laboratory. By combining the lowest background levels with the best energy resolution in the field, LEGEND-1000 will perform a quasi-background-free search and can make an unambiguous discovery of neutrinoless double-beta decay with just a handful of counts at the decay $Q$ value. The experiment is designed to probe this decay with a 99.7%-CL discovery sensitivity in the $^{76}$Ge half-life of $1.3\times10^{28}$ years, corresponding to an effective Majorana mass upper limit in the range of 9-21 meV, to cover the inverted-ordering neutrino mass scale with 10 yr of live time.
Published: 2021

11. Characterization of inverted coaxial $^{76}$Ge detectors in GERDA for future double-$\beta$ decay experiments

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

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

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

Author: GERDA collaboration, Agostini, M., Bakalyarov, A. M., Balata, M., Barabanov, I., Baudis, L., Bauer, C., Bellotti, E., Belogurov, S., Bettini, A., Bezrukov, L., Borowicz, D., Bossio, E., Bothe, V., Brudanin, V., Brugnera, R., Caldwell, A., Cattadori, C., Chernogorov, A., Comellato, T., D'Andrea, V., Demidova, E. V., Di Marco, N., Doroshkevich, E., Egorov, V., Fischer, F., Fomina, M., Gangapshev, A., Garfagnini, A., Gooch, C., Grabmayr, P., Gurentsov, V., Gusev, K., Hakenmüller, J., Hemmer, S., Hiller, R., Hofmann, W., Hult, M., Inzhechik, L. V., Csáthy, J. Janicskó, Jochum, J., Junker, M., Kazalov, V., Kermaïdic, Y., Khushbakht, H., Kihm, T., Kirpichnikov, I. V., Klimenko, A., Kneißl, R., Knöpfle, K. T., Kochetov, O., Kornoukhov, V. N., Krause, P., Kuzminov, V. V., Laubenstein, M., Lazzaro, A., Lindner, M., Lippi, I., Lubashevskiy, A., Lubsandorzhiev, B., Lutter, G., Macolino, C., Majorovits, B., Maneschg, W., Miloradovic, M., Mingazheva, R., Misiaszek, M., Moseev, P., Nemchenok, I., Panas, K., Pandola, L., Pelczar, K., Pertoldi, L., Piseri, P., Pullia, A., Ransom, C., Rauscher, L., Riboldi, S., Rumyantseva, N., Sada, C., Salamida, F., Schönert, S., Schreiner, J., Schütt, M., Schütz, A-K., Schulz, O., Schwarz, M., Schwingenheuer, B., Selivanenko, O., Shevchik, E., Shirchenko, M., Simgen, H., Smolnikov, A., Stukov, D., Vasenko, A. A., Veresnikova, A., Vignoli, C., von Sturm, K., Wester, T., Wiesinger, C., Wojcik, M., Yanovich, E., Zatschler, B., Zhitnikov, I., Zhukov, S. V., Zinatulina, D., Zschocke, A., Zsigmond, A. J., and Zuzel, K. Zuber G.
Subjects: High Energy Physics - Experiment, Nuclear Experiment
Abstract: We present the first search for bosonic super-WIMPs as keV-scale dark matter candidates performed with the GERDA experiment. GERDA is a neutrinoless double-beta decay experiment which operates high-purity germanium detectors enriched in $^{76}$Ge in an ultra-low background environment at the Laboratori Nazionali del Gran Sasso (LNGS) of INFN in Italy. Searches were performed for pseudoscalar and vector particles in the mass region from 60 keV/c$^2$ to 1 MeV/c$^2$. No evidence for a dark matter signal was observed, and the most stringent constraints on the couplings of super-WIMPs with masses above 120 keV/c$^2$ have been set. As an example, at a mass of 150 keV/c$^2$ the most stringent direct limits on the dimensionless couplings of axion-like particles and dark photons to electrons of $g_{ae} < 3 \cdot 10^{-12}$ and ${\alpha'}/{\alpha} < 6.5 \cdot 10^{-24}$ at 90% credible interval, respectively, were obtained., Comment: 6 pages, 3 figures, submitted to Physical Review Letters, added list of authors, updated ref. [21]
Published: 2020
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15. Search for tri-nucleon decays of 76Ge in GERDA

Author: Agostini, M., Alexander, A., Araujo, G., Bakalyarov, A. M., Balata, M., Barabanov, I., Baudis, L., Bauer, C., Belogurov, S., Bettini, A., Bezrukov, L., Biancacci, V., Bossio, E., Bothe, V., Brugnera, R., Caldwell, A., Calgaro, S., Cattadori, C., Chernogorov, A., Chiu, P.-J., Comellato, T., D’Andrea, V., Demidova, E. V., Di Giacinto, A., Di Marco, N., Doroshkevich, E., Fischer, F., Fomina, M., Gangapshev, A., Garfagnini, A., Gooch, C., Grabmayr, P., Gurentsov, V., Gusev, K., Hakenmüller, J., Hemmer, S., Hofmann, W., Hult, M., Inzhechik, L. V., Janicskó Csáthy, J., Jochum, J., Junker, M., Kazalov, V., Kermaïdic, Y., Khushbakht, H., Kihm, T., Kilgus, K., Kirpichnikov, I. V., Klimenko, A., Knöpfle, K. T., Kochetov, O., Kornoukhov, V. N., Krause, P., Kuzminov, V. V., Laubenstein, M., Lindner, M., Lippi, I., Lubashevskiy, A., Lubsandorzhiev, B., Lutter, G., Macolino, C., Majorovits, B., Maneschg, W., Manzanillas, L., Marshall, G., Misiaszek, M., Morella, M., Müller, Y., Nemchenok, I., Neuberger, M., Pandola, L., Pelczar, K., Pertoldi, L., Piseri, P., Pullia, A., Rauscher, L., Redchuk, M., Riboldi, S., Rumyantseva, N., Sada, C., Sailer, S., Salamida, F., Schönert, S., Schreiner, J., Schütt, M., Schütz, A.-K., Schulz, O., Schwarz, M., Schwingenheuer, B., Selivanenko, O., Shevchik, E., Shirchenko, M., Shtembari, L., Simgen, H., Smolnikov, A., Stukov, D., Sullivan, S., Vasenko, A. A., Veresnikova, A., Vignoli, C., von Sturm, K., Wester, T., Wiesinger, C., Wojcik, M., Yanovich, E., Zatschler, B., Zhitnikov, I., Zhukov, S. V., Zinatulina, D., Zschocke, A., Zsigmond, A. J., Zuber, K., and Zuzel, G.
Published: 2023
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16. Enriched high purity germanium detectors for the LEGEND-200 experiment: purification and characterization by quadrupole and high resolution inductively coupled plasma mass spectrometry (ICP-MS)

Author: Ferella, F., Nisi, S., Balata, M., Grabmayr, P., Laubenstein, M., Schwingenheuer, B., and Schönert, S.
Published: 2023
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17. Probing Majorana neutrinos with double-$\beta$ decay

Author: GERDA collaboration, Agostini, M., Bakalyarov, A. M., Balata, M., Barabanov, I., Baudis, L., Bauer, C., Bellotti, E., Belogurov, S., Bettini, A., Bezrukov, L., Borowicz, D., Brudanin, V., Brugnera, R., Caldwell, A., Cattadori, C., Chernogorov, A., Comellato, T., D'Andrea, V., Demidova, E. V., Di Marco, N., Domula, A., Doroshkevich, E., Egorov, V., Falkenstein, R., Fomina, M., Gangapshev, A., Garfagnini, A., Giordano, M., Grabmayr, P., Gurentsov, V., Gusev, K., Hakenmüller, J., Hegai, A., Heisel, M., Hemmer, S., Hiller, R., Hofmann, W., Hult, M., Inzhechik, L. V., Csáthy, J. Janicskó, Jochum, J., Junker, M., Kazalov, V., Kermaïdic, Y., Kihm, T., Kirpichnikov, I. V., Kirsch, A., Kish, A., Klimenko, A., Kneißl, R., Knöpfle, K. T., Kochetov, O., Kornoukhov, V. N., Krause, P., Kuzminov, V. V., Laubenstein, M., Lazzaro, A., Lindner, M., Lippi, I., Lubashevskiy, A., Lubsandorzhiev, B., Lutter, G., Macolino, C., Majorovits, B., Maneschg, W., Miloradovic, M., Mingazheva, R., Misiaszek, M., Moseev, P., Nemchenok, I., Panas, K., Pandola, L., Pelczar, K., Pertoldi, L., Piseri, P., Pullia, A., Ransom, C., Riboldi, S., Rumyantseva, N., Sada, C., Sala, E., Salamida, F., Schmitt, C., Schneider, B., Schönert, S., Schütz, A. -K., Schulz, O., Schwingenheuer, B., Schwarz, M., Selivanenko, O., Shevchik, E., Shirchenko, M., Simgen, H., Smolnikov, A., Stanco, L., Stukov, D., Vanhoefer, L., Vasenko, A. A., Veresnikova, A., von Sturm, K., Wagner, V., Wegmann, A., Wester, T., Wiesinger, C., Wojcik, M., Yanovich, E., Zhitnikov, I., Zhukov, S. V., Zinatulina, D., Zschocke, A., Zsigmond, A. J., Zuber, K., and Zuzel, G.
Subjects: High Energy Physics - Experiment, Nuclear Experiment
Abstract: A discovery that neutrinos are not the usual Dirac but Majorana fermions, i.e. identical to their antiparticles, would be a manifestation of new physics with profound implications for particle physics and cosmology. Majorana neutrinos would generate neutrinoless double-$\beta$ ($0\nu\beta\beta$) decay, a matter-creating process without the balancing emission of antimatter. So far, 0$\nu\beta\beta$ decay has eluded detection. The GERDA collaboration searches for the $0\nu\beta\beta$ decay of $^{76}$Ge by operating bare germanium detectors in an active liquid argon shield. With a total exposure of 82.4 kg$\cdot$yr, we observe no signal and derive a lower half-life limit of T$_{1/2}$ > 0.9$\cdot$10$^{26}$ yr (90% C.L.). Our T$_{1/2}$ sensitivity assuming no signal is 1.1$\cdot$10$^{26}$ yr. Combining the latter with those from other $0{\nu}\beta\beta$ decay searches yields a sensitivity to the effective Majorana neutrino mass of 0.07 - 0.16 eV, with corresponding sensitivities to the absolute mass scale in $\beta$ decay of 0.15 - 0.44 eV, and to the cosmological relevant sum of neutrino masses of 0.46 - 1.3 eV., Comment: Authors' main+supplementary text: 13+28 pages, 3+12 figures, 1+7 tables. Definite version to be published in Science
Published: 2019
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18. Characterization of 30 $^{76}$Ge enriched Broad Energy Ge detectors for GERDA Phase II

Author: GERDA collaboration, Agostini, M., Bakalyarov, A. M., Andreotti, E., Balata, M., Barabanov, I., Baudis, L., Barros, N., Bauer, C., Bellotti, E., Belogurov, S., Benato, G., Bettini, A., Bezrukov, L., Bode, T., Borowicz, D., Brudanin, V., Brugnera, R., Budjáš, D., Caldwell, A., Cattadori, C., Chernogorov, A., D'Andrea, V., Demidova, E. V., Di Marco, N., Domula, A., Doroshkevich, E., Egorov, V., Falkenstein, R., Freund, K., Gangapshev, A., Garfagnini, A., Gooch, C., Grabmayr, P., Gurentsov, V., Gusev, K., Hakenmüller, J., Hegai, A., Heisel, M., Hemmer, S., Hiller, R., Hofmann, W., Hult, M., Inzhechik, L. V., Csáthy, J. Janicskó, Jochum, J., Junker, M., Kazalov, V., Kermaidic, Y., Kihm, T., Kirpichnikov, I. V., Kirsch, A., Kish, A., Klimenko, A., Kneißl, R., Knöpfle, K. T., Kochetov, O., Kornoukhov, V. N., Kuzminov, V. V., Laubenstein, M., Lazzaro, A., Lehnert, B., Liao, Y., Lindner, M., Lippi, I., Lubashevskiy, A., Lubsandorzhiev, B., Lutter, G., Macolino, C., Majorovits, B., Maneschg, W., Miloradovic, M., Mingazheva, R., Misiaszek, M., Moseev, P., Nemchenok, I., Panas, K., Pandola, L., Pelczar, K., Pullia, A., Ransom, C., Riboldi, S., Rumyantseva, N., Sada, C., Salamida, F., Salathe, M., Schmitt, C., Schneider, B., Schönert, S., Schütz, A-K., Schulz, O., Schwingenheuer, B., Selivanenko, O., Shevchik, E., Shirchenko, M., Simgen, H., Smolnikov, A., Stanco, L., Ur, C. A., Vanhoefer, L., Vasenko, A. A., Veresnikova, A., von Sturm, K., Wagner, V., Wegmann, A., Wester, T., Wiesinger, C., Wojcik, M., Yanovich, E., Zhitnikov, I., Zhukov, S. V., Zinatulina, D., Zsigmond, A. J., Zuber, K., and Zuzel, G.
Subjects: Physics - Instrumentation and Detectors
Abstract: The GERmanium Detector Array (GERDA) is a low background experiment located at the Laboratori Nazionali del Gran Sasso in Italy, which searches for neutrinoless double beta decay of $^{76}$Ge into $^{76}$Se+2e$^-$. GERDA has been conceived in two phases. Phase II, which started in December 2015, features several novelties including 30 new Ge detectors. These were manufactured according to the Broad Energy Germanium (BEGe) detector design that has a better background discrimination capability and energy resolution compared to formerly widely-used types. Prior to their installation, the new BEGe detectors were mounted in vacuum cryostats and characterized in detail in the HADES underground laboratory in Belgium. This paper describes the properties and the overall performance of these detectors during operation in vacuum. The characterization campaign provided not only direct input for GERDA Phase II data collection and analyses, but also allowed to study detector phenomena, detector correlations as well as to test the strength of pulse shape simulation codes., Comment: 29 pages, 18 figures
Published: 2019
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19. Liquid argon light collection and veto modeling in GERDA Phase II

Author: Agostini, M., Alexander, A., Araujo, G. R., Bakalyarov, A. M., Balata, M., Barabanov, I., Baudis, L., Bauer, C., Belogurov, S., Bettini, A., Bezrukov, L., Biancacci, V., Bossio, E., Bothe, V., Brugnera, R., Caldwell, A., Calgaro, S., Cattadori, C., Chernogorov, A., Chiu, P. -J., Comellato, T., D’Andrea, V., Demidova, E. V., Di Giacinto, A., Di Marco, N., Doroshkevich, E., Fischer, F., Fomina, M., Gangapshev, A., Garfagnini, A., Gooch, C., Grabmayr, P., Gurentsov, V., Gusev, K., Hakenmüller, J., Hemmer, S., Hofmann, W., Hult, M., Inzhechik, L. V., Csáthy, J. Janicskó, Jochum, J., Junker, M., Kazalov, V., Kermaïdic, Y., Khushbakht, H., Kihm, T., Kilgus, K., Kirpichnikov, I. V., Klimenko, A., Knöpfle, K. T., Kochetov, O., Kornoukhov, V. N., Krause, P., Kuzminov, V. V., Laubenstein, M., Lehnert, B., Lindner, M., Lippi, I., Lubashevskiy, A., Lubsandorzhiev, B., Lutter, G., Macolino, C., Majorovits, B., Maneschg, W., Manzanillas, L., Marshall, G., Miloradovic, M., Mingazheva, R., Misiaszek, M., Morella, M., Müller, Y., Nemchenok, I., Neuberger, M., Pandola, L., Pelczar, K., Pertoldi, L., Piseri, P., Pullia, A., Rauscher, L., Redchuk, M., Riboldi, S., Rumyantseva, N., Sada, C., Sailer, S., Salamida, F., Schönert, S., Schreiner, J., Schütt, M., Schütz, A. -K., Schulz, O., Schwarz, M., Schwingenheuer, B., Selivanenko, O., Shevchik, E., Shirchenko, M., Shtembari, L., Simgen, H., Smolnikov, A., Stukov, D., Sullivan, S., Vasenko, A. A., Veresnikova, A., Vignoli, C., von Sturm, K., Wegmann, A., Wester, T., Wiesinger, C., Wojcik, M., Yanovich, E., Zatschler, B., Zhitnikov, I., Zhukov, S. V., Zinatulina, D., Zschocke, A., Zsigmond, A. J., Zuber, K., and Zuzel, G.
Published: 2023
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20. Improved limit on neutrinoless double beta decay of $^{76}$Ge from GERDA Phase II

Author: Agostini, M., Bakalyarov, A. M., 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, E. V., 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, L. V., Csáthy, J. Janicskó, Jochum, J., Junker, M., Kazalov, V., Kermaidic, Y., Kihm, T., Kirpichnikov, I. V., Kirsch, A., Kish, A., Klimenko, A., Kneißl, R., Knöpfle, K. T., Kochetov, O., Kornoukhov, V. N., Kuzminov, V. V., Laubenstein, M., Lazzaro, A., 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, A-K., Schulz, O., Schwingenheuer, B., Selivanenko, O., Shevchik, E., Shirchenko, M., Simgen, H., Smolnikov, A., Stanco, L., Vanhoefer, L., Vasenko, A. A., Veresnikova, A., von Sturm, K., Wagner, V., Wegmann, A., Wester, T., Wiesinger, C., Wojcik, M., Yanovich, E., Zhitnikov, I., Zhukov, S. V., Zinatulina, D., Zschocke, A., Zsigmond, A. J., Zuber, K., and Zuzel, G.
Subjects: Nuclear Experiment, Physics - Instrumentation and Detectors
Abstract: The GERDA experiment searches for the lepton number violating neutrinoless double beta decay of $^{76}$Ge ($^{76}$Ge $\rightarrow$ $^{76}$Se + 2e$^-$) operating bare Ge diodes with an enriched $^{76}$Ge fraction in liquid argon. The exposure for BEGe-type 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 $1.0_{-0.4}^{+0.6}\cdot10^{-3}$ cts/(keV$\cdot$kg$\cdot$yr) has been achieved; if normalized to the energy resolution this is the lowest ever achieved in any 0$\nu\beta\beta$ experiment. No signal is observed and a new 90 \% C.L. lower limit for the half-life of $8.0\cdot10^{25}$ yr is placed when combining with our previous data. The median expected sensitivity assuming no signal is $5.8\cdot10^{25}$ yr., Comment: 5 pages, 2 figures
Published: 2018
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21. Characterization of 30 76Ge enriched Broad Energy Ge detectors for GERDA Phase II

Author: Agostini, M, Bakalyarov, AM, Andreotti, E, Balata, M, Barabanov, I, Baudis, L, Barros, N, Bauer, C, Bellotti, E, Belogurov, S, Benato, G, Bettini, A, Bezrukov, L, Bode, T, Borowicz, D, Brudanin, V, Brugnera, R, Budjáš, D, Caldwell, A, Cattadori, C, Chernogorov, A, D’Andrea, V, Demidova, EV, Di Marco, N, Domula, A, Doroshkevich, E, Egorov, V, Falkenstein, R, Freund, K, Gangapshev, A, Garfagnini, A, Gooch, C, Grabmayr, P, Gurentsov, V, Gusev, K, Hakenmüller, J, Hegai, A, Heisel, M, Hemmer, S, Hiller, R, Hofmann, W, Hult, M, Inzhechik, LV, Csáthy, J Janicskó, Jochum, J, Junker, M, Kazalov, V, Kermaïdic, Y, Kihm, T, Kirpichnikov, IV, Kirsch, A, Kish, A, Klimenko, A, Kneißl, R, Knöpfle, KT, Kochetov, O, Kornoukhov, VN, Kuzminov, VV, Laubenstein, M, Lazzaro, A, Lehnert, B, Liao, Y, Lindner, M, Lippi, I, Lubashevskiy, A, Lubsandorzhiev, B, Lutter, G, Macolino, C, Majorovits, B, Maneschg, W, Marissens, G, Miloradovic, M, Mingazheva, R, Misiaszek, M, Moseev, P, Nemchenok, I, Panas, K, Pandola, L, Pelczar, K, Pullia, A, Ransom, C, Riboldi, S, Rumyantseva, N, Sada, C, Salamida, F, Salathe, M, Schmitt, C, Schneider, B, Schönert, S, Schütz, A-K, Schulz, O, Schwingenheuer, B, Selivanenko, O, Shevchik, E, Shirchenko, M, Simgen, H, Smolnikov, A, Stanco, L, Vanhoefer, L, and Vasenko, AA
Subjects: GERDA Collaboration, physics.ins-det, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics
Abstract: The GERmanium Detector Array (Gerda) is a low background experiment located at the Laboratori Nazionali del Gran Sasso in Italy, which searches for neutrinoless double-beta decay of 76 Ge into 76 Se+2e - . Gerda has been conceived in two phases. Phase II, which started in December 2015, features several novelties including 30 new 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

22. Upgrade for Phase II of the GERDA Experiment

Author: Agostini, M., Bakalyarov, A. M., Balata, M., Barabanov, I., Baudis, L., Bauer, C., Bellotti, E., Belogurov, S., Belyaev, S. T., Benato, G., Bettini, A., Bezrukov, L., Bode, T., Borowicz, D., Brudanin, V., Brugnera, R., Caldwell, A., Cattadori, C., Chernogorov, A., D'Andrea, V., Demidova, E. V., Di Marco, N., Domula, A., Doroshkevich, E., Egorov, V., Falkenstein, R., Frodyma, N., 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, L. V., Ioannucci, L., Csathy, J. Janicsko, Jochum, J., Junker, M., Kazalov, V., Kermaidic, Y., Kihm, T., Kirpichnikov, I. V., Kirsch, A., Kish, A., Klimenko, A., Kneissl, R., Knöpfle, K. T., Kochetov, O., Kornoukhov, V. N., Kuzminov, V. V., Laubenstein, M., Lazzaro, A., Lebedev, V. I., Lehnert, B., Lindner, M., Lippi, I., Lubashevskiy, A., Lubsandorzhiev, B., Lutter, G., Macolino, C., Majorovits, B., Maneschg, W., Medinaceli, E., Miloradovic, M., Mingazheva, R., Misiaszek, M., Moseev, P., Nemchenok, I., Nisi, S., Panas, K., Pandola, L., Pelczar, K., Pullia, A., Ransom, C., Riboldi, S., Rumyantseva, N., Sada, C., Salamida, F., Salathe, M., Schmitt, C., Schneider, B., Schönert, S., Schreiner, J., Schütz, A-K., Schulz, O., Schwingenheuer, B., Selivanenko, O., Shevchik, E., Shirchenko, M., Simgen, H., Smolnikov, A., Stanco, L., Vanhoefer, L., Vasenko, A. A., Veresnikova, A., von Sturm, K., Wagner, V., Wegmann, A., Wester, T., Wiesinger, C., Wojcik, M., Yanovich, E., Zhitnikov, I., Zhukov, S. V., Zinatulina, D., Zsigmond, A. J., Zuber, K., and Zuzel, G.
Subjects: Physics - Instrumentation and Detectors, Nuclear Experiment
Abstract: The GERDA collaboration is performing a sensitive search for neutrinoless double beta decay of $^{76}$Ge at the INFN Laboratori Nazionali del Gran Sasso, Italy. The upgrade of the GERDA experiment from Phase I to Phase II has been concluded in December 2015. The first Phase II data release shows that the goal to suppress the background by one order of magnitude compared to Phase I has been achieved. GERDA is thus the first experiment that will remain background-free up to its design exposure (100 kg yr). It will reach thereby a half-life sensitivity of more than 10$^{26}$ yr within 3 years of data collection. This paper describes in detail the modifications and improvements of the experimental setup for Phase II and discusses the performance of individual detector components., Comment: 31 pages, 34 figures
Published: 2017
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23. Pulse shape discrimination performance of Inverted Coaxial Ge detectors

Author: Domula, A., Hult, M., Kermaidic, Y., Marissens, G., Schwingenheuer, B., Wester, T., and Zuber, K.
Subjects: Physics - Instrumentation and Detectors, High Energy Physics - Experiment, Nuclear Experiment
Abstract: We report on the characterization of two inverted coaxial Ge detectors in the context of being employed in future $^{76}$Ge neutrinoless double beta ($0\nu\beta\beta$) decay experiments. It is an advantage that such detectors can be produced with bigger Ge mass as compared to the planar Broad Energy Ge detectors (BEGe) that are currently used in the GERDA $0\nu\beta\beta$ decay experiment. This will result in lower background for the search of $0\nu\beta\beta$ decay due to a reduction of cables, electronics and holders. The measured resolution near the $^{76}$Ge Q-value at 2039 keV is 2.5 keV and their pulse-shape characteristics are similar to BEGe-detectors. It is concluded that this type of Ge-detector is suitable for usage in $^{76}$Ge $0\nu\beta\beta$ decay experiments.
Published: 2017
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24. Searching for neutrinoless double beta decay with GERDA

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

25. The Large Enriched Germanium Experiment for Neutrinoless Double Beta Decay (LEGEND)

Author: LEGEND Collaboration, Abgrall, N., Abramov, A., Abrosimov, N., Abt, I., Agostini, M., Agartioglu, M., Ajjaq, A., Alvis, S. I., Avignone III, F. T., Bai, X., Balata, M., Barabanov, I., Barabash, A. S., Barton, P. J., Baudis, L., Bezrukov, L., Bode, T., Bolozdynya, A., Borowicz, D., Boston, A., Boston, H., Boyd, S. T. P., Breier, R., Brudanin, V., Brugnera, R., Busch, M., Buuck, M., Caldwell, A., Caldwell, T. S., Camellato, T., Carpenter, M., Cattadori, C., Cederkäll, J., Chan, Y. -D., Chen, S., Chernogorov, A., Christofferson, C. D., Chu, P. -H., Cooper, R. J., Cuesta, C., Demidova, E. V., Deng, Z., Deniz, M., Detwiler, J. A., Di Marco, N., Domula, A., Du, Q., Efremenko, Yu., Egorov, V., Elliott, S. R., Fields, D., Fischer, F., Galindo-Uribarri, A., Gangapshev, A., Garfagnini, A., Gilliss, T., Giordano, M., Giovanetti, G. K., Gold, M., Golubev, P., Gooch, C., Grabmayr, P., Green, M. P., Gruszko, J., Guinn, I. S., Guiseppe, V. E., Gurentsov, V., Gurov, Y., Gusev, K., Hakenmüeller, J., Harkness-Brennan, L., Harvey, Z. R., Haufe, C. R., Hauertmann, L., Heglund, D., Hehn, L., Heinz, A., Hiller, R., Hinton, J., Hodak, R., Hofmann, W., Howard, S., Howe, M. A., Hult, M., Inzhechik, L. V., Csáthy, J. Janicskó, Janssens, R., Ješkovský, M., Jochum, J., Johansson, H. T., Judson, D., Junker, M., Kaizer, J., Kang, K., Kazalov, V., Kermaïdic, Y., Kiessling, F., Kirsch, A., Kish, A., Klimenko, A., Knöpfle, K. T. K. T., Kochetov, O., Konovalov, S. I., Kontul, I., Kornoukhov, V. N., Kraetzschmar, T., Kröninger, K., Kumar, A., Kuzminov, V. V., Lang, K., Laubenstein, M., Lazzaro, A., Li, Y. L., Li, Y. -Y., Li, H. B., Lin, S. T., Lindner, M., Lippi, I., Liu, S. K., Liu, X., Liu, J., Loomba, D., Lubashevskiy, A., Lubsandorzhiev, B., Lutter, G., Ma, H., Majorovits, B., Mamedov, F., Martin, R. D., Massarczyk, R., Matthews, J. A. J., McFadden, N., Mei, D. -M., Mei, H., Meijer, S. J., Mengoni, D., Mertens, S., Miller, W., Miloradovic, M., Mingazheva, R., Misiaszek, M., Moseev, P., Myslik, J., Nemchenok, I., Nilsson, T., Nolan, P., O'Shaughnessy, C., Othman, G., Panas, K., Pandola, L., Papp, L., Pelczar, K., Peterson, D., Pettus, W., Poon, A. W. P., Povinec, P. P., Pullia, A., Quintana, X. C., Radford, D. C., Rager, J., Ransom, C., Recchia, F., Reine, A. L., Riboldi, S., Rielage, K., Rozov, S., Rouf, N. W., Rukhadze, E., Rumyantseva, N., Saakyan, R., Sala, E., Salamida, F., Sandukovsky, V., Savard, G., Schönert, S., Schütz, A. -K., Schulz, O., Schuster, M., Schwingenheuer, B., Selivanenko, O., Sevda, B., Shanks, B., Shevchik, E., Shirchenko, M., Simkovic, F., Singh, L., Singh, V., Skorokhvatov, M., Smolek, K., Smolnikov, A., Sonay, A., Spavorova, M., Stekl, I., Stukov, D., Tedeschi, D., Thompson, J., Van Wechel, T., Varner, R. L., Vasenko, A. A., Vasilyev, S., Veresnikova, A., Vetter, K., von Sturm, K., Vorren, K., Wagner, M., Wang, G. -J., Waters, D., Wei, W. -Z., Wester, T., White, B. R., Wiesinger, C., Wilkerson, J. F., Willers, M., Wiseman, C., Wojcik, M., Wong, H. T., Wyenberg, J., Xu, W., Yakushev, E., Yang, G., Yu, C. -H., Yue, Q., Yumatov, V., Zeman, J., Zeng, Z., Zhitnikov, I., Zhu, B., Zinatulina, D., Zschocke, A., Zsigmond, A. J., Zuber, K., and Zuzel, G.
Subjects: Physics - Instrumentation and Detectors, High Energy Physics - Experiment, Nuclear Experiment
Abstract: The observation of neutrinoless double-beta decay (0${\nu}{\beta}{\beta}$) would show that lepton number is violated, reveal that neutrinos are Majorana particles, and provide information on neutrino mass. A discovery-capable experiment covering the inverted ordering region, with effective Majorana neutrino masses of 15 - 50 meV, will require a tonne-scale experiment with excellent energy resolution and extremely low backgrounds, at the level of $\sim$0.1 count /(FWHM$\cdot$t$\cdot$yr) in the region of the signal. The current generation $^{76}$Ge experiments GERDA and the MAJORANA DEMONSTRATOR utilizing high purity Germanium detectors with an intrinsic energy resolution of 0.12%, have achieved the lowest backgrounds by over an order of magnitude in the 0${\nu}{\beta}{\beta}$ signal region of all 0${\nu}{\beta}{\beta}$ experiments. Building on this success, the LEGEND collaboration has been formed to pursue a tonne-scale $^{76}$Ge experiment. The collaboration aims to develop a phased 0${\nu}{\beta}{\beta}$ experimental program with discovery potential at a half-life approaching or at $10^{28}$ years, using existing resources as appropriate to expedite physics results., Comment: Proceedings of the MEDEX'17 meeting (Prague, May 29 - June 2, 2017)
Published: 2017
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26. Background free search for neutrinoless double beta decay with GERDA Phase II

Author: Agostini, M., Allardt, M., Bakalyarov, A. M., Balata, M., Barabanov, I., Baudis, L., Bauer, C., Bellotti, E., Belogurov, S., Belyaev, S. T., Benato, G., Bettini, A., Bezrukov, L., Bode, T., Borowicz, D., Brudanin, V., Brugnera, R., Caldwell, A., Cattadori, C., Chernogorov, A., D'Andrea, V., Demidova, E. V., DiMarco, N., diVacri, A., Domula, A., Doroshkevich, E., Egorov, V., Falkenstein, R., Fedorova, O., Freund, K., Frodyma, N., Gangapshev, A., Garfagnini, A., Gooch, C., Grabmayr, P., Gurentsov, V., Gusev, K., Hakenmüller, J., Hegai, A., Heisel, M., Hemmer, S., Hofmann, W., Hult, M., Inzhechik, L. V., Csáthy, J. Janicskó, Jochum, J., Junker, M., Kazalov, V., Kihm, T., Kirpichnikov, I. V., Kirsch, A., Kish, A., Klimenko, A., Kneißl, R., Knöpfle, K. T., Kochetov, O., Kornoukhov, V. N., Kuzminov, V. V., Laubenstein, M., Lazzaro, A., Lebedev, V. I., Lehnert, B., Liao, H. Y., Lindner, M., Lippi, I., Lubashevskiy, A., Lubsandorzhiev, B., Lutter, G., Macolino, C., Majorovits, B., Maneschg, W., Medinaceli, E., Miloradovic, M., Mingazheva, R., Misiaszek, M., Moseev, P., Nemchenok, I., Palioselitis, D., Panas, K., Pandola, L., Pelczar, K., Pullia, A., Riboldi, S., Rumyantseva, N., Sada, C., Salamida, F., Salathe, M., Schmitt, C., Schneider, B., Schönert, S., Schreiner, J., Schulz, O., Schütz, A. -K., Schwingenheuer, B., Selivanenko, O., Shevchik, E., Shirchenko, M., Simgen, H., Smolnikov, A., Stanco, L., Vanhoefer, L., Vasenko, A. A., Veresnikova, A., von Sturm, K., Wagner, V., Walter, M., Wegmann, A., Wester, T., Wiesinger, C., Wojcik, M., Yanovich, E., Zhitnikov, I., Zhukov, S. V., Zinatulina, D., Zuber, K., and Zuzel, G.
Subjects: Nuclear Experiment, High Energy Physics - Experiment, Physics - Instrumentation and Detectors
Abstract: The Standard Model of particle physics cannot explain the dominance of matter over anti-matter in our Universe. In many model extensions this is a very natural consequence of neutrinos being their own anti-particles (Majorana particles) which implies that a lepton number violating radioactive decay named neutrinoless double beta ($0\nu\beta\beta$) decay should exist. The detection of this extremely rare hypothetical process requires utmost suppression of any kind of backgrounds. The GERDA collaboration searches for $0\nu\beta\beta$ decay of $^{76}$Ge ($^{76}\rm{Ge} \rightarrow\,^{76}\rm{Se} + 2e^-$) by operating bare detectors made from germanium with enriched $^{76}$Ge fraction in liquid argon. Here, we report on first data of GERDA Phase II. A background level of $\approx10^{-3}$ cts/(keV$\cdot$kg$\cdot$yr) has been achieved which is the world-best if weighted by the narrow energy-signal region of germanium detectors. Combining Phase I and II data we find no signal and deduce a new lower limit for the half-life of $5.3\cdot10^{25}$ yr at 90 % C.L. Our sensitivity of $4.0\cdot10^{25}$ yr is competitive with the one of experiments with significantly larger isotope mass. GERDA is the first $0\nu\beta\beta$ experiment that will be background-free up to its design exposure. This progress relies on a novel active veto system, the superior germanium detector energy resolution and the improved background recognition of our new detectors. The unique discovery potential of an essentially background-free search for $0\nu\beta\beta$ decay motivates a larger germanium experiment with higher sensitivity., Comment: 14 pages, 9 figures, 1 table; ; data, figures and images available at http://www.mpi-hd.mpg/gerda/public
Published: 2017
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27. Upgrade for Phase II of the Gerda experiment

Author: GERDA Collaboration, Agostini, M, Bakalyarov, AM, Balata, M, Barabanov, I, Baudis, L, Bauer, C, Bellotti, E, Belogurov, S, Belyaev, ST, Benato, G, Bettini, A, Bezrukov, L, Bode, T, Borowicz, D, Brudanin, V, Brugnera, R, Caldwell, A, Cattadori, C, Chernogorov, A, D’Andrea, V, Demidova, EV, Di Marco, N, Domula, A, Doroshkevich, E, Egorov, V, Falkenstein, R, Frodyma, N, 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, Ioannucci, L, 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, Kuzminov, VV, Laubenstein, M, Lazzaro, A, Lebedev, VI, Lehnert, B, Lindner, M, Lippi, I, Lubashevskiy, A, Lubsandorzhiev, B, Lutter, G, Macolino, C, Majorovits, B, Maneschg, W, Medinaceli, E, Miloradovic, M, Mingazheva, R, Misiaszek, M, Moseev, P, Nemchenok, I, Nisi, S, Panas, K, Pandola, L, Pelczar, K, Pullia, A, Ransom, C, Riboldi, S, Rumyantseva, N, Sada, C, Salamida, F, Salathe, M, Schmitt, C, Schneider, B, Schönert, S, Schreiner, J, Schütz, A-K, Schulz, O, Schwingenheuer, B, Selivanenko, O, Shevchik, E, Shirchenko, M, Simgen, H, Smolnikov, A, Stanco, L, and Vanhoefer, L
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, physics.ins-det, nucl-ex, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Astronomical sciences, Atomic, molecular and optical physics, Particle and high energy physics
Abstract: The Gerda collaboration is performing a sensitive search for neutrinoless double beta decay of 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 (100 kgyear). It will reach thereby a half-life sensitivity of more than 10 26 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

28. Upgrade for Phase II of the Gerda experiment

Author: Agostini, M, Bakalyarov, AM, Balata, M, Barabanov, I, Baudis, L, Bauer, C, Bellotti, E, Belogurov, S, Belyaev, ST, Benato, G, Bettini, A, Bezrukov, L, Bode, T, Borowicz, D, Brudanin, V, Brugnera, R, Caldwell, A, Cattadori, C, Chernogorov, A, D’Andrea, V, Demidova, EV, Di Marco, N, Domula, A, Doroshkevich, E, Egorov, V, Falkenstein, R, Frodyma, N, 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, Ioannucci, L, 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, Kuzminov, VV, Laubenstein, M, Lazzaro, A, Lebedev, VI, Lehnert, B, Lindner, M, Lippi, I, Lubashevskiy, A, Lubsandorzhiev, B, Lutter, G, Macolino, C, Majorovits, B, Maneschg, W, Medinaceli, E, Miloradovic, M, Mingazheva, R, Misiaszek, M, Moseev, P, Nemchenok, I, Nisi, S, Panas, K, Pandola, L, Pelczar, K, Pullia, A, Ransom, C, Riboldi, S, Rumyantseva, N, Sada, C, Salamida, F, Salathe, M, Schmitt, C, Schneider, B, Schönert, S, Schreiner, J, Schütz, AK, Schulz, O, Schwingenheuer, B, Selivanenko, O, Shevchik, E, Shirchenko, M, Simgen, H, Smolnikov, A, Stanco, L, Vanhoefer, L, and Vasenko, AA
Subjects: physics.ins-det, nucl-ex, Nuclear & Particles Physics, Quantum Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics
Abstract: The Gerda collaboration is performing a sensitive search for neutrinoless double beta decay of 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 (100 kgyear). It will reach thereby a half-life sensitivity of more than 10 26 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

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

Author: GERDA collaboration, Agostini, M., Allardt, M., Bakalyarov, A. M., Balata, M., Barabanov, I., Baudis, L., Bauer, C., Becerici-Schmidt, N., Bellotti, E., Belogurov, S., Belyaev, S. T., Benato, G., Bettini, A., Bezrukov, L., Bode, T., Borowicz, D., Brudanin, V., Brugnera, R., Caldwell, A., Cattadori, C., Chernogorov, A., D'Andrea, V., Demidova, E. V., di Vacri, A., Domula, A., Doroshkevich, E., Egorov, V., Falkenstein, R., Fedorova, O., Freund, K., Frodyma, N., Gangapshev, A., Garfagnini, A., Grabmayr, P., Gurentsov, V., Gusev, K., Hakemüller, J., Hegai, A., Heisel, M., Hemmer, S., Hofmann, W., Hult, M., Inzhechik, L. V., Csathy, J. Janicsko, Jochum, J., Junker, M., Kazalov, V., Kihm, T., Kirpichnikov, I. V., Kirsch, A., Kish, A., Klimenko, A., Kneißl, R., Knöpfle, K. T., Kochetov, O., Kornoukhov, V. N., Kuzminov, V. V., Laubenstein, M., Lazzaro, A., Lebedev, V. I., Lehnert, B., Liao, H. Y., Lindner, M., Lippi, I., Lubashevskiy, A., Lubsandorzhiev, B., Lutter, G., Macolino, C., Majorovits, B., Maneschg, W., Medinaceli, E., Mingazheva, R., Misiaszek, M., Moseev, P., Nemchenok, I., Palioselitis, D., Panas, K., Pandola, L., Pelczar, K., Pullia, A., Riboldi, S., Rumyantseva, N., Sada, C., Salamida, F., Salathe, M., Schmitt, C., Schneider, B., Schönert, S., Schreiner, J., Schütz, A. -K., Schulz, O., Schwingenheuer, B., Selivanenko, O., Shevchik, E., Shirchenko, M., Simgen, H., Smolnikov, A., Stanco, L., Stepaniuk, M., Vanhoefer, L., Vasenko, A. A., Veresnikova, A., von Sturm, K., Wagner, V., Walter, M., Wegmann, A., Wester, T., Wiesinger, C., Wojcik, M., Yanovich, E., Zhitnikov, I., Zhukov, S. V., Zinatulina, D., Zuber, K., and Zuzel, G.
Subjects: Physics - Instrumentation and Detectors, Nuclear Experiment
Abstract: Internal contaminations of $^{238}$U, $^{235}$U and $^{232}$Th in the bulk of high purity germanium detectors are potential backgrounds for experiments searching for neutrinoless double beta decay of $^{76}$Ge. The data from GERDA Phase~I have been analyzed for alpha events from the decay chain of these contaminations by looking for full decay chains and for time correlations between successive decays in the same detector. No candidate events for a full chain have been found. Upper limits on the activities in the range of a few nBq/kg for $^{226}$Ra, $^{227}$Ac and $^{228}$Th, the long-lived daughter nuclides of $^{238}$U, $^{235}$U and $^{232}$Th, respectively, have been derived. With these upper limits a background index in the energy region of interest from $^{226}$Ra and $^{228}$Th contamination is estimated which satisfies the prerequisites of a future ton scale germanium double beta decay experiment., Comment: 2 figures, 7 pages
Published: 2016
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30. Limit on the Radiative Neutrinoless Double Electron Capture of $^{36}$Ar from GERDA Phase I

Author: Agostini, M., Allardt, M., Bakalyarov, A. M., Balata, M., Barabanov, I., Barros, N., Baudis, L., Bauer, C., Bellotti, E., Belogurov, S., Belyaev, S. T., Benato, G., Bettini, A., Bezrukov, L., Bode, T., Borowicz, D., Brudanin, V., Brugnera, R., Caldwell, A., Cattadori, C., Chernogorov, A., D'Andrea, V., Demidova, E. V., di Vacri, A., Domula, A., Doroshkevich, E., Egorov, V., Falkenstein, R., Fedorova, O., Freund, K., Frodyma, N., Gangapshev, A., Garfagnini, A., Gooch, C., Grabmayr, P., Gurentsov, V., Gusev, K., Hakenmüller, J., Hegai, A., Heisel, M., Hemmer, S., Heusser, G., Hofmann, W., Hult, M., Inzhechik, L. V., Csáthy, J. Janicskó, Jochum, J., Junker, M., Kazalov, V., Kihm, T., Kirpichnikov, I. V., Kirsch, A., Kish, A., Klimenko, A., Kneißl, R., Knöpfle, K. T., Kochetov, O., Kornoukhov, V. N., Kuzminov, V. V., Laubenstein, M., Lazzaro, A., Lebedev, V. I., Lehnert, B., Liao, H. Y., Lindner, M., Lippi, I., Lubashevskiy, A., Lubsandorzhiev, B., Lutter, G., Macolino, C., Majorovits, B., Maneschg, W., Medinaceli, E., Miloradovic, M., Mingazheva, R., Misiaszek, M., Moseev, P., Nemchenok, I., Palioselitis, D., Panas, K., Pandola, L., Pelczar, K., Pullia, A., Riboldi, S., Rumyantseva, N., Sada, C., Salamida, F., Salathe, M., Schmitt, C., Schneider, B., Schönert, S., Schreiner, J., Schütz, A. -K., Schulz, O., Schwingenheuer, B., Selivanenko, O., Shirchenko, M., Simgen, H., Smolnikov, A., Stanco, L., Stepaniuk, M., Vanhoefer, L., Vasenko, A. A., Veresnikova, A., von Sturm, K., Wagner, V., Walter, M., Wegmann, A., Wester, T., Wiesinger, C., Wilsenach, H., Wojcik, M., Yanovich, E., Zhitnikov, I., Zhukov, S. V., Zinatulina, D., Zuber, K., and Zuzel, G.
Subjects: Nuclear Experiment, High Energy Physics - Experiment
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., Comment: 7 pages, 3 figures
Published: 2016
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31. Flux Modulations seen by the Muon Veto of the GERDA Experiment

Author: Agostini, M., Allardt, M., Bakalyarov, A. M., Balata, M., Barabanov, I., Barros, N., Baudis, L., Bauer, C., Becerici-Schmidt, N., Bellotti, E., Belogurov, S., Belyaev, S. T., Benato, G., Bettini, A., Bezrukov, L., Bode, T., Borowicz, D., Brudanin, V., Brugnera, R., Caldwell, A., Cattadori, C., Chernogorov, A., D'Andrea, V., Demidova, E. V., di Vacri, A., Domula, A., Doroshkevich, E., Egorov, V., Falkenstein, R., Fedorova, O., Freund, K., Frodyma, N., Gangapshev, A., Garfagnini, A., Grabmayr, P., Gurentsov, V., Gusev, K., Hegai, A., Heisel, M., Hemmer, S., Hofmann, W., Hult, M., Inzhechik, L. V., Ioannucci, L., Csáthy, J. Janicskó, Jochum, J., Junker, M., Kazalov, V., Kihm, T., Kirpichnikov, I. V., Kirsch, A., Klimenko, A., Knapp, M., Knöpfle, K. T., Kochetov, O., Kornoukhov, V. N., Kuzminov, V. V., Laubenstein, M., Lazzaro, A., Lebedev, V. I., Lehnert, B., Liao, H. Y., Lindner, M., Lippi, I., Lubashevskiy, A., Lubsandorzhiev, B., Lutter, G., Macolino, C., Majorovits, B., Maneschg, W., Medinaceli, E., Misiaszek, M., Moseev, P., Nemchenok, I., Palioselitis, D., Panas, K., Pandola, L., Pelczar, K., Pullia, A., Riboldi, S., Ritter, F., Rumyantseva, N., Sada, C., Salathe, M., Schmitt, C., Schneider, B., Schönert, S., Schreiner, J., Schütz, A. -K., Schulz, O., Schwingenheuer, B., Selivanenko, O., Shevchik, E., Shirchenko, M., Simgen, H., Smolnikov, A., Stanco, L., Stepaniuk, M., Strecker, H., Vanhoefer, L., Vasenko, A. A., Veresnikova, A., vonSturm, K., Wagner, V., Walter, M., Wegmann, A., Wester, T., Wilsenach, H., Wojcik, M., Yanovich, E., Zhitnikov, I., Zhukov, S. V., Zinatulina, D., Zuber, K., and Zuzel, G.
Subjects: Physics - Instrumentation and Detectors, High Energy Physics - Experiment
Abstract: The GERDA experiment at LNGS of INFN is equipped with an active muon veto. The main part of the system is a water Cherenkov veto with 66~PMTs in the water tank surrounding the GERDA cryostat. The muon flux recorded by this veto shows a seasonal modulation. Two effects have been identified which are caused by secondary muons from the CNGS neutrino beam (2.2 %) and a temperature modulation of the atmosphere (1.4 %). A mean cosmic muon rate of $I^0_{\mu} = (3.477 \pm 0.002_{\textrm{stat}} \pm 0.067_{\textrm{sys}}) \times 10^{-4}$/(s$\cdot$m$^2$) was found in good agreement with other experiments at LNGS at a depth of 3500~meter water equivalent., Comment: 7 pages, 6 figures
Published: 2016
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32. First results from GERDA Phase II

Author: Agostini, M, Allardt, M, Bakalyarov, AM, Balata, M, Barabanov, I, Baudis, L, Bauer, C, Bellotti, E, Belogurov, S, Belyaev, ST, Benato, G, Bettini, A, Bezrukov, L, Bode, T, Borowicz, D, Brudanin, V, Brugnera, R, Caldwell, A, Cattadori, C, Chernogorov, A, D’Andrea, V, Demidova, EV, Di Marco, N, Domula, A, Doroshkevich, E, Egorov, V, Falkenstein, R, Frodyma, N, Gangapshev, A, Garfagnini, A, Gooch, C, Grabmayr, P, Gurentsov, V, Gusev, K, Hakenmüller, J, Hegai, A, Heisel, M, Hemmer, S, Hofmann, W, Hult, M, Inzhechik, LV, Csáthy, J Janicskó, Jochum, J, Junker, M, Kazalov, V, Kihm, T, Kirpichnikov, IV, Kirsch, A, Kish, A, Klimenko, A, Kneißl, R, Knöpfle, KT, Kochetov, O, Kornoukhov, VN, Kuzminov, VV, Laubenstein, M, Lazzaro, A, Lebedev, VI, Lehnert, B, Liao, HY, Lindner, M, Lippi, I, Lubashevskiy, A, Lubsandorzhiev, B, Lutter, G, Macolino, C, Majorovits, B, Maneschg, W, Medinaceli, E, Miloradovic, M, Mingazheva, R, Misiaszek, M, Moseev, P, Nemchenok, I, Palioselitis, D, Panas, K, Pandola, L, Pelczar, K, Pullia, A, Riboldi, S, Rumyantseva, N, Sada, C, Salamida, F, Salathe, M, Schmitt, C, Schneider, B, Schönert, S, Schreiner, J, Schulz, O, Schütz, A-K, Schwingenheuer, B, Selivanenko, O, Shevchik, E, Shirchenko, M, Simgen, H, Smolnikov, A, Stanco, L, Vanhoefer, L, Vasenko, AA, and Veresnikova, A
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Condensed Matter Physics, Other Physical Sciences, Physical sciences
Abstract: Gerda is designed for a background-free search of 76Ge neutrinoless double-β decay, using bare Ge detectors in liquid Ar. The experiment was upgraded after the successful completion of Phase I to double the target mass and further reduce the background. Newly-designed Ge detectors were installed along with LAr scintillation sensors. Phase II of data-taking started in Dec 2015 with approximately 36 kg of Ge detectors and is currently ongoing. The first results based on 10.8 kg• yr of exposure are presented. The background goal of 10-3 cts/(keV• kg• yr) is achieved and a search for neutrinoless double-β decay is performed by combining Phase I and II data. No signal is found and a new limit is set at yr (90% C.L.).
Published: 2017

33. Study of the GERDA Phase II background spectrum

Author: Agostini, M, Allardt, M, Bakalyarov, AM, Balata, M, Barabanov, I, Baudis, L, Bauer, C, Bellotti, E, Belogurov, S, Belyaev, ST, Benato, G, Bettini, A, Bezrukov, L, Bode, T, Borowicz, D, Brudanin, V, Brugnera, R, Caldwell, A, Cattadori, C, Chernogorov, A, D’Andrea, V, Demidova, EV, Di Marco, N, Domula, A, Doroshkevich, E, Egorov, V, Falkenstein, R, Frodyma, N, Gangapshev, A, Garfagnini, A, Gooch, C, Grabmayr, P, Gurentsov, V, Gusev, K, Hakenmüller, J, Hegai, A, Heisel, M, Hemmer, S, Hofmann, W, Hult, M, Inzhechik, LV, Csáthy, J Janicskó, Jochum, J, Junker, M, Kazalov, V, Kihm, T, Kirpichnikov, IV, Kirsch, A, Kish, A, Klimenko, A, Kneißl, R, Knöpfle, KT, Kochetov, O, Kornoukhov, VN, Kuzminov, VV, Laubenstein, M, Lazzaro, A, Lebedev, VI, Lehnert, B, Liao, HY, Lindner, M, Lippi, I, Lubashevskiy, A, Lubsandorzhiev, B, Lutter, G, Macolino, C, Majorovits, B, Maneschg, W, Medinaceli, E, Miloradovic, M, Mingazheva, R, Misiaszek, M, Moseev, P, Nemchenok, I, Palioselitis, D, Panas, K, Pandola, L, Pelczar, K, Pullia, A, Riboldi, S, Rumyantseva, N, Sada, C, Salamida, F, Salathe, M, Schmitt, C, Schneider, B, Schönert, S, Schreiner, J, Schulz, O, Schütz, A-K, Schwingenheuer, B, Selivanenko, O, Shevzik, E, Shirchenko, M, Simgen, H, Smolnikov, A, Stanco, L, Vanhoefer, L, Vasenko, AA, and Veresnikova, A
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Condensed Matter Physics, Other Physical Sciences, Physical sciences
Abstract: The Gerda experiment, located at the Laboratori Nazionali del Gran Sasso (LNGS) of INFN in Italy, searches for the neutrinoless double beta (0νββ) decay of 76Ge. Gerda Phase II is aiming to reach a sensitivity for the 0νββ half life of 1026 yr in ∼ 3 years of physics data taking with 100 kg•yr of exposure and a background index of ∼ 10-3 cts/(keV•kg•yr). After 6 months of acquisition a first data release with 10.8 kg•yr of exposure is performed, showing that the design background is achieved. In this work a study of the Phase II background spectrum, the main spectral structures and the background sources will be presented and discussed.
Published: 2017

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

Author: Agostini, M, Allardt, M, Bakalyarov, AM, Balata, M, Barabanov, I, Baudis, L, Bauer, C, Bellotti, E, Belogurov, S, Belyaev, ST, Benato, G, Bettini, A, Bezrukov, L, Bode, T, Borowicz, D, Brudanin, V, Brugnera, R, Caldwell, A, Cattadori, C, Chernogorov, A, D’Andrea, V, Demidova, EV, Di Marco, N, Domula, A, Doroshkevich, E, Egorov, V, Falkenstein, R, Frodyma, N, Gangapshev, A, Garfagnini, A, Gooch, C, Grabmayr, P, Gurentsov, V, Gusev, K, Hakenmüller, J, Hegai, A, Heisel, M, Hemmer, S, Hofmann, W, Hult, M, Inzhechik, LV, Csáthy, J Janicskó, Jochum, J, Junker, M, Kazalov, V, Kihm, T, Kirpichnikov, IV, Kirsch, A, Kish, A, Klimenko, A, Kneißl, R, Knöpfle, KT, Kochetov, O, Kornoukhov, VN, Kuzminov, VV, Laubenstein, M, Lazzaro, A, Lebedev, VI, Lehnert, B, Liao, HY, Lindner, M, Lippi, I, Lubashevskiy, A, Lubsandorzhiev, B, Lutter, G, Macolino, C, Majorovits, B, Maneschg, W, Medinaceli, E, Miloradovic, M, Mingazheva, R, Misiaszek, M, Moseev, P, Nemchenok, I, Palioselitis, D, Panas, K, Pandola, L, Pelczar, K, Pullia, A, Riboldi, S, Rumyantseva, N, Sada, C, Salamida, F, Salathe, M, Schmitt, C, Schneider, B, Schönert, S, Schreiner, J, Schulz, O, Schütz, A-K, Schwingenheuer, B, Selivanenko, O, Shevzik, E, Shirchenko, M, Simgen, H, Smolnikov, A, Stanco, L, Vanhoefer, L, Vasenko, AA, and Veresnikova, A
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Condensed Matter Physics, Other Physical Sciences, Physical sciences
Abstract: The observation of neutrinoless double beta decay would allow to shed light onto the particle nature of neutrinos. Gerda is aiming to perform a background-free search for this process using high purity germanium detectors enriched in 76Ge operated in liquid argon. This goal relies on the application of active background suppression techniques. A low background light instrumentation has been installed for Phase II to detect events with coincident energy deposition in the nearby liquid argon. The intended background index of ∼10-3 cts/(keV•ky•yr) has been confirmed.
Published: 2017

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

Author: collaboration, G, Agostini, M, Allardt, M, Bakalyarov, AM, Balata, M, Barabanov, I, Baudis, L, Bauer, C, Becerici-Schmidt, N, Bellotti, E, Belogurov, S, Belyaev, ST, Benato, G, Bettini, A, Bezrukov, L, Bode, T, Borowicz, D, Brudanin, V, Brugnera, R, Caldwell, A, Cattadori, C, Chernogorov, A, D'Andrea, V, Demidova, EV, di Vacri, A, Domula, A, Doroshkevich, E, Egorov, V, Falkenstein, R, Fedorova, O, Freund, K, Frodyma, N, Gangapshev, A, Garfagnini, A, Grabmayr, P, Gurentsov, V, Gusev, K, Hakemüller, J, Hegai, A, Heisel, M, Hemmer, S, Hofmann, W, Hult, M, Inzhechik, LV, Janicskó Csáthy, J, Jochum, J, Junker, M, Kazalov, V, Kihm, T, Kirpichnikov, IV, Kirsch, A, Kish, A, Klimenko, A, Kneißl, R, Knöpfle, KT, Kochetov, O, Kornoukhov, VN, Kuzminov, VV, Laubenstein, M, Lazzaro, A, Lebedev, VI, Lehnert, B, Liao, HY, Lindner, M, Lippi, I, Lubashevskiy, A, Lubsandorzhiev, B, Lutter, G, Macolino, C, Majorovits, B, Maneschg, W, Medinaceli, E, Mingazheva, R, Misiaszek, M, Moseev, P, Nemchenok, I, Palioselitis, D, Panas, K, Pandola, L, Pelczar, K, Pullia, A, Riboldi, S, Rumyantseva, N, Sada, C, Salamida, F, Salathe, M, Schmitt, C, Schneider, B, Schönert, S, Schreiner, J, Schütz, AK, Schulz, O, Schwingenheuer, B, Selivanenko, O, Shevchik, E, Shirchenko, M, Simgen, H, Smolnikov, A, Stanco, L, and Stepaniuk, M
Subjects: Germanium detectors, Double beta decay, Radiopurity, Uranium and thorium bulk content, physics.ins-det, nucl-ex, Nuclear & Particles Physics, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics
Abstract: Internal contaminations of 238U, 235U and 232Th in the bulk of high purity germanium detectors are potential backgrounds for experiments searching for neutrinoless double beta decay of 76Ge. 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 226Ra, 227Ac and 228Th, the long-lived daughter nuclides of 238U, 235U and 232Th, respectively, have been derived. With these upper limits a background index in the energy region of interest from 226Ra and 228Th contamination is estimated which satisfies the prerequisites of a future ton scale germanium double beta decay experiment.
Published: 2017

36. Limits on uranium and thorium bulk content in Gerda Phase I detectors

Author: collaboration, GERDA, Agostini, M, Allardt, M, Bakalyarov, AM, Balata, M, Barabanov, I, Baudis, L, Bauer, C, Becerici-Schmidt, N, Bellotti, E, Belogurov, S, Belyaev, ST, Benato, G, Bettini, A, Bezrukov, L, Bode, T, Borowicz, D, Brudanin, V, Brugnera, R, Caldwell, A, Cattadori, C, Chernogorov, A, D’Andrea, V, Demidova, EV, di Vacri, A, Domula, A, Doroshkevich, E, Egorov, V, Falkenstein, R, Fedorova, O, Freund, K, Frodyma, N, Gangapshev, A, Garfagnini, A, Grabmayr, P, Gurentsov, V, Gusev, K, Hakemüller, J, Hegai, A, Heisel, M, Hemmer, S, Hofmann, W, Hult, M, Inzhechik, LV, Csáthy, J Janicskó, Jochum, J, Junker, M, Kazalov, V, Kihm, T, Kirpichnikov, IV, Kirsch, A, Kish, A, Klimenko, A, Kneißl, R, Knöpfle, KT, Kochetov, O, Kornoukhov, VN, Kuzminov, VV, Laubenstein, M, Lazzaro, A, Lebedev, VI, Lehnert, B, Liao, HY, Lindner, M, Lippi, I, Lubashevskiy, A, Lubsandorzhiev, B, Lutter, G, Macolino, C, Majorovits, B, Maneschg, W, Medinaceli, E, Mingazheva, R, Misiaszek, M, Moseev, P, Nemchenok, I, Palioselitis, D, Panas, K, Pandola, L, Pelczar, K, Pullia, A, Riboldi, S, Rumyantseva, N, Sada, C, Salamida, F, Salathe, M, Schmitt, C, Schneider, B, Schönert, S, Schreiner, J, Schütz, A-K, Schulz, O, Schwingenheuer, B, Selivanenko, O, Shevchik, E, Shirchenko, M, Simgen, H, Smolnikov, A, Stanco, L, and Stepaniuk, M
Subjects: Germanium detectors, Double beta decay, Radiopurity, Uranium and thorium bulk content, physics.ins-det, nucl-ex, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Nuclear & Particles Physics
Abstract: Internal contaminations of 238U, 235U and 232Th in the bulk of high purity germanium detectors are potential backgrounds for experiments searching for neutrinoless double beta decay of 76Ge. 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 226Ra, 227Ac and 228Th, the long-lived daughter nuclides of 238U, 235U and 232Th, respectively, have been derived. With these upper limits a background index in the energy region of interest from 226Ra and 228Th contamination is estimated which satisfies the prerequisites of a future ton scale germanium double beta decay experiment.
Published: 2017

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

Author: Agostini, M, Allardt, M, Bakalyarov, AM, Balata, M, Barabanov, I, Baudis, L, Bauer, C, Bellotti, E, Belogurov, S, Belyaev, ST, Benato, G, Bettini, A, Bezrukov, L, Bode, T, Borowicz, D, Brudanin, V, Brugnera, R, Caldwell, A, Cattadori, C, Chernogorov, A, D’Andrea, V, Demidova, EV, Di Marco, N, Domula, A, Doroshkevich, E, Egorov, V, Falkenstein, R, Frodyma, N, Gangapshev, A, Garfagnini, A, Gooch, C, Grabmayr, P, Gurentsov, V, Gusev, K, Hakenmüller, J, Hegai, A, Heisel, M, Hemmer, S, Hofmann, W, Hult, M, Inzhechik, LV, Csáthy, J Janicskó, Jochum, J, Junker, M, Kazalov, V, Kihm, T, Kirpichnikov, IV, Kirsch, A, Kish, A, Klimenko, A, Kneißl, R, Knöpfle, KT, Kochetov, O, Kornoukhov, VN, Kuzminov, VV, Laubenstein, M, Lazzaro, A, Lebedev, VI, Lehnert, B, Liao, HY, Lindner, M, Lippi, I, Lubashevskiy, A, Lubsandorzhiev, B, Lutter, G, Macolino, C, Majorovits, B, Maneschg, W, Medinaceli, E, Miloradovic, M, Mingazheva, R, Misiaszek, M, Moseev, P, Nemchenok, I, Palioselitis, D, Panas, K, Pandola, L, Pelczar, K, Pullia, A, Riboldi, S, Rumyantseva, N, Sada, C, Salamida, F, Salathe, M, Schmitt, C, Schneider, B, Schönert, S, Schreiner, J, Schulz, O, Schütz, A-K, Schwingenheuer, B, Selivanenko, O, Shevzik, E, Shirchenko, M, Simgen, H, Smolnikov, A, Stanco, L, Vanhoefer, L, Vasenko, AA, and Veresnikova, A
Subjects: Physical Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Condensed Matter Physics, Other Physical Sciences, Physical sciences
Abstract: The GERDA (GERmanium Detector Array) is an experiment for the search of neutrinoless double beta decay (0νββ) in 76Ge, located at Laboratori Nazionali del Gran Sasso of INFN (Italy). GERDA operates bare high purity germanium detectors submersed in liquid Argon (LAr). Phase II of data-taking started in Dec 2015 and is currently ongoing. In Phase II 35 kg of germanium detectors enriched in 76Ge including thirty newly produced Broad Energy Germanium (BEGe) detectors is operating to reach an exposure of 100 kg•yr within about 3 years data taking. The design goal of Phase II is to reduce the background by one order of magnitude to get the sensitivity for . To achieve the necessary background reduction, the setup was complemented with LAr veto. Analysis of the background spectrum of Phase II demonstrates consistency with the background models. Furthermore 226Ra and 232Th contamination levels consistent with screening results. In the first Phase II data release we found no hint for a 0νββ decay signal and place a limit of this process yr (90% C.L., sensitivity 4.0•1025 yr). First results of GERDA Phase II will be presented.
Published: 2017

38. Limit on the radiative neutrinoless double electron capture of 36Ar from GERDA Phase I

Author: Agostini, M, Allardt, M, Bakalyarov, AM, Balata, M, Barabanov, I, Barros, N, Baudis, L, Bauer, C, Bellotti, E, Belogurov, S, Belyaev, ST, Benato, G, Bettini, A, Bezrukov, L, Bode, T, Borowicz, D, Brudanin, V, Brugnera, R, Caldwell, A, Cattadori, C, Chernogorov, A, D’Andrea, V, Demidova, EV, di Vacri, A, Domula, A, Doroshkevich, E, Egorov, V, Falkenstein, R, Fedorova, O, Freund, K, Frodyma, N, Gangapshev, A, Garfagnini, A, Gooch, C, Grabmayr, P, Gurentsov, V, Gusev, K, Hakenmüller, J, Hegai, A, Heisel, M, Hemmer, S, Heusser, G, Hofmann, W, Hult, M, Inzhechik, LV, Csáthy, J Janicskó, Jochum, J, Junker, M, Kazalov, V, Kihm, T, Kirpichnikov, IV, Kirsch, A, Kish, A, Klimenko, A, Kneißl, R, Knöpfle, KT, Kochetov, O, Kornoukhov, VN, Kuzminov, VV, Laubenstein, M, Lazzaro, A, Lebedev, VI, Lehnert, B, Liao, HY, Lindner, M, Lippi, I, Lubashevskiy, A, Lubsandorzhiev, B, Lutter, G, Macolino, C, Majorovits, B, Maneschg, W, Medinaceli, E, Miloradovic, M, Mingazheva, R, Misiaszek, M, Moseev, P, Nemchenok, I, Palioselitis, D, Panas, K, Pandola, L, Pelczar, K, Pullia, A, Riboldi, S, Rumyantseva, N, Sada, C, Salamida, F, Salathe, M, Schmitt, C, Schneider, B, Schönert, S, Schreiner, J, Schütz, A-K, Schulz, O, Schwingenheuer, B, Selivanenko, O, Shirchenko, M, Simgen, H, Smolnikov, A, and Stanco, L
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, nucl-ex, hep-ex, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Astronomical sciences, Atomic, molecular and optical physics, Particle and high energy physics
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 36Ar 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 36Ar was established: T1 / 2> 3.6 × 1021 years at 90% CI.
Published: 2016

39. Limit on the radiative neutrinoless double electron capture of 36 Ar from GERDA Phase I

Author: Agostini, M, Allardt, M, Bakalyarov, AM, Balata, M, Barabanov, I, Barros, N, Baudis, L, Bauer, C, Bellotti, E, Belogurov, S, Belyaev, ST, Benato, G, Bettini, A, Bezrukov, L, Bode, T, Borowicz, D, Brudanin, V, Brugnera, R, Caldwell, A, Cattadori, C, Chernogorov, A, D’Andrea, V, Demidova, EV, di Vacri, A, Domula, A, Doroshkevich, E, Egorov, V, Falkenstein, R, Fedorova, O, Freund, K, Frodyma, N, Gangapshev, A, Garfagnini, A, Gooch, C, Grabmayr, P, Gurentsov, V, Gusev, K, Hakenmüller, J, Hegai, A, Heisel, M, Hemmer, S, Heusser, G, Hofmann, W, Hult, M, Inzhechik, LV, Csáthy, JJ, Jochum, J, Junker, M, Kazalov, V, Kihm, T, Kirpichnikov, IV, Kirsch, A, Kish, A, Klimenko, A, Kneißl, R, Knöpfle, KT, Kochetov, O, Kornoukhov, VN, Kuzminov, VV, Laubenstein, M, Lazzaro, A, Lebedev, VI, Lehnert, B, Liao, HY, Lindner, M, Lippi, I, Lubashevskiy, A, Lubsandorzhiev, B, Lutter, G, Macolino, C, Majorovits, B, Maneschg, W, Medinaceli, E, Miloradovic, M, Mingazheva, R, Misiaszek, M, Moseev, P, Nemchenok, I, Palioselitis, D, Panas, K, Pandola, L, Pelczar, K, Pullia, A, Riboldi, S, Rumyantseva, N, Sada, C, Salamida, F, Salathe, M, Schmitt, C, Schneider, B, Schönert, S, Schreiner, J, Schütz, AK, Schulz, O, Schwingenheuer, B, Selivanenko, O, Shirchenko, M, Simgen, H, Smolnikov, A, and Stanco, L
Subjects: nucl-ex, hep-ex, Nuclear & Particles Physics, Quantum Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics
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 36Ar 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 36Ar was established: T1 / 2> 3.6 × 1021 years at 90% CI.
Published: 2016

40. $2\nu\beta\beta$ decay of $^{76}$Ge into excited states with GERDA Phase I

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

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

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

Author: Agostini, M., Allardt, M., Bakalyarov, A. M., Balata, M., Barabanov, I., Barros, N., Baudis, L., Bauer, C., Becerici-Schmidt, N., Bellotti, E., Belogurov, S., Belyaev, S. T., Benato, G., Bettini, A., Bezrukov, L., Bode, T., Borowicz, D., Brudanin, V., Brugnera, R., Budjáš, D., Caldwell, A., Cattadori, C., Chernogorov, A., D'Andrea, V., Demidova, E. V., di Vacri, A., Domula, A., Doroshkevich, E., Egorov, V., Falkenstein, R., Fedorova, O., Freund, K., Frodyma, N., Gangapshev, A., Garfagnini, A., Grabmayr, P., Gurentsov, V., Gusev, K., Hegai, A., Heisel, M., Hemmer, S., Heusser, G., Hofmann, W., Hult, M., Inzhechik, L. V., Csáthy, J. Janicskó, Jochum, J., Junker, M., Kazalov, V., Kihm, T., Kirpichnikov, I. V., Kirsch, A., Klimenko, A., Knöpfle, K. T., Kochetov, O., Kornoukhov, V. N., Kuzminov, V. V., Laubenstein, M., Lazzaro, A., Lebedev, V. I., Lehnert, B., Liao, H. Y., Lindner, M., Lippi, I., Lubashevskiy, A., Lubsandorzhiev, B., Lutter, G., Macolino, C., Majorovits, B., Maneschg, W., Medinaceli, E., Misiaszek, M., Moseev, P., Nemchenok, I., Palioselitis, D., Panas, K., Pandola, L., Pelczar, K., Pullia, A., Riboldi, S., Rumyantseva, N., Sada, C., Salathe, M., Schmitt, C., Schreiner, J., Schulz, O., Schwingenheuer, B., Schönert, S., Selivanenko, O., Shirchenko, M., Simgen, H., Smolnikov, A., Stanco, L., Stepaniuk, M., Ur, C. A., Vanhoefer, L., Vasenko, A. A., Veresnikova, A., von Sturm, K., Wagner, V., Walter, M., Wegmann, A., Wester, T., Wilsenach, H., Wojcik, M., Yanovich, E., Zavarise, P., Zhitnikov, I., Zhukov, S. V., Zinatulina, D., Zuber, K., and Zuzel, G.
Subjects: Nuclear Experiment, Physics - Instrumentation and Detectors
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., Comment: 3 Figures
Published: 2015
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43. Pulse shape analysis in Gerda Phase II

Author: Agostini, M., Araujo, G., Bakalyarov, A. M., Balata, M., Barabanov, I., Baudis, L., Bauer, C., Bellotti, E., Belogurov, S., Bettini, A., Bezrukov, L., Biancacci, V., Bossio, E., Bothe, V., Brudanin, V., Brugnera, R., Caldwell, A., Cattadori, C., Chernogorov, A., Comellato, T., D’Andrea, V., Demidova, E. V., Marco, N. Di, Doroshkevich, E., Fischer, F., Fomina, M., Gangapshev, A., Garfagnini, A., Gooch, C., Grabmayr, P., Gurentsov, V., Gusev, K., Hakenmüller, J., Hemmer, S., Hiller, R., Hofmann, W., Huang, J., Hult, M., Inzhechik, L. V., Csáthy, J. Janicskó, Jochum, J., Junker, M., Kazalov, V., Kermaïdic, Y., Khushbakht, H., Kihm, T., Kilgus, K., Kirsch, A., Kirpichnikov, I. V., Klimenko, A., Knöpfle, K. T., Kochetov, O., Kornoukhov, V. N., Krause, P., Kuzminov, V. V., Laubenstein, M., Lazzaro, A., Lindner, M., Lippi, I., Lubashevskiy, A., Lubsandorzhiev, B., Lutter, G., Macolino, C., Majorovits, B., Maneschg, W., Manzanillas, L., Miloradovic, M., Mingazheva, R., Misiaszek, M., Müller, Y., Nemchenok, I., Panas, K., Pandola, L., Pelczar, K., Pertoldi, L., Piseri, P., Pullia, A., Ransom, C., Rauscher, L., Redchuk, M., Riboldi, S., Rumyantseva, N., Sada, C., Salamida, F., Schönert, S., Schreiner, J., Schütt, M., Schütz, A. -K., Schulz, O., Schwarz, M., Schwingenheuer, B., Selivanenko, O., Shevchik, E., Shirchenko, M., Shtembari, L., Simgen, H., Smolnikov, A., Stukov, D., Vasenko, A. A., Veresnikova, A., Vignoli, C., Sturm, K. von, Wagner, V., Wester, T., Wiesinger, C., Wojcik, M., Yanovich, E., Zatschler, B., Zhitnikov, I., Zhukov, S. V., Zinatulina, D., Zschocke, A., Zsigmond, A. J., Zuber, K., and Zuzel, G.
Published: 2022
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44. Flux modulations seen by the muon veto of the Gerda experiment

Author: collaboration, GERDA, Agostini, M, Allardt, M, Bakalyarov, AM, Balata, M, Barabanov, I, Barros, N, Baudis, L, Bauer, C, Becerici-Schmidt, N, Bellotti, E, Belogurov, S, Belyaev, ST, Benato, G, Bettini, A, Bezrukov, L, Bode, T, Borowicz, D, Brudanin, V, Brugnera, R, Caldwell, A, Cattadori, C, Chernogorov, A, D’Andrea, V, Demidova, EV, di Vacri, A, Domula, A, Doroshkevich, E, Egorov, V, Falkenstein, R, Fedorova, O, Freund, K, Frodyma, N, Gangapshev, A, Garfagnini, A, Grabmayr, P, Gurentsov, V, Gusev, K, Hegai, A, Heisel, M, Hemmer, S, Hofmann, W, Hult, M, Inzhechik, LV, Ioannucci, L, Cs’athy, J Janicsk’o, Jochum, J, Junker, M, Kazalov, V, Kihm, T, Kirpichnikov, IV, Kirsch, A, Klimenko, A, Knapp, M, Knöpfle, KT, Kochetov, O, Kornoukhov, VN, Kuzminov, VV, Laubenstein, M, Lazzaro, A, Lebedev, VI, Lehnert, B, Liao, HY, Lindner, M, Lippi, I, Lubashevskiy, A, Lubsandorzhiev, B, Lutter, G, Macolino, C, Majorovits, B, Maneschg, W, Medinaceli, E, Misiaszek, M, Moseev, P, Nemchenok, I, Palioselitis, D, Panas, K, Pandola, L, Pelczar, K, Pullia, A, Riboldi, S, Ritter, F, Rumyantseva, N, Sada, C, Salathe, M, Schmitt, C, Schneider, B, Schönert, S, Schreiner, J, Schütz, A-K, Schulz, O, Schwingenheuer, B, Selivanenko, O, Shevchik, E, Shirchenko, M, Simgen, H, Smolnikov, A, Stanco, L, Stepaniuk, M, and Strecker, H
Subjects: Water cherenkov detector, Underground experiment, Cosmic rays, Muon interaction, physics.ins-det, hep-ex, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Nuclear & Particles Physics
Abstract: The GERDA experiment at LNGS of INFN is equipped with an active muon veto. The main part of the system is a water Cherenkov veto with 66 PMTs in the water tank surrounding the GERDA cryostat. The muon flux recorded by this veto shows a seasonal modulation. Two causes have been identified: (i) secondary muons from the CNGS neutrino beam (2.2%) and (ii) a temperature modulation of the atmosphere (1.4%). A mean cosmic muon rate of Iμ0=(3.477±0.002stat±0.067sys)×10−4/(s · m2) was found in good agreement with other experiments at LNGS. Combining the present result with those from previous experiments at LNGS the effective temperature coefficient αT,Lngs is determined to 0.93 ± 0.03. A fit of the temperature coefficients measured at various underground sites yields a kaon to pion ratio rK/π of 0.10 ± 0.03.
Published: 2016

45. Flux modulations seen by the muon veto of the GERDA experiment

Author: Agostini, M, Balata, M, D'Andrea, V, di Vacri, A, Ioannucci, L, Junker, M, Laubenstein, M, Macolino, C, Pandola, L, Borowicz, D, Frodyma, N, Misiaszek, M, Panas, K, Pelczar, K, Wojcik, M, Zuzel, G, Allardt, M, Barros, N, Domula, A, Lehnert, B, Schneider, B, Wester, T, Wilsenach, H, Zuber, K, Brudanin, V, Egorov, V, Gusev, K, Klimenko, A, Kochetov, O, Lubashevskiy, A, Nemchenok, I, Rumyantseva, N, Shevchik, E, Shirchenko, M, Zhitnikov, I, Zinatulina, D, Hult, M, Lutter, G, Bauer, C, Gangapshev, A, Heisel, M, Hofmann, W, Kihm, T, Kirsch, A, Knöpfle, KT, Lindner, M, Maneschg, W, Salathe, M, Schreiner, J, Schwingenheuer, B, Simgen, H, Smolnikov, A, Stepaniuk, M, Strecker, H, Wagner, V, Wegmann, A, Bellotti, E, Cattadori, C, Pullia, A, Riboldi, S, Barabanov, I, Belogurov, S, Bezrukov, L, Doroshkevich, E, Fedorova, O, Gurentsov, V, Inzhechik, LV, Kazalov, V, Kornoukhov, VN, Kuzminov, VV, Lubsandorzhiev, B, Moseev, P, Selivanenko, O, Veresnikova, A, Yanovich, E, Chernogorov, A, Demidova, EV, Kirpichnikov, IV, Vasenko, AA, Bakalyarov, AM, Belyaev, ST, Lebedev, VI, Zhukov, SV, Becerici-Schmidt, N, Caldwell, A, Liao, HY, Majorovits, B, Palioselitis, D, Schulz, O, Vanhoefer, L, Bode, T, Janicsk'o Cs'athy, J, Lazzaro, A, Schönert, S, Wiesinger, C, Bettini, A, Brugnera, R, Garfagnini, A, Hemmer, S, and Medinaceli, E
Subjects: Water cherenkov detector, Underground experiment, Cosmic rays, Muon interaction, physics.ins-det, hep-ex, Nuclear & Particles Physics, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics
Abstract: The GERDA experiment at LNGS of INFN is equipped with an active muon veto. The main part of the system is a water Cherenkov veto with 66 PMTs in the water tank surrounding the GERDA cryostat. The muon flux recorded by this veto shows a seasonal modulation. Two causes have been identified: (i) secondary muons from the CNGS neutrino beam (2.2%) and (ii) a temperature modulation of the atmosphere (1.4%). A mean cosmic muon rate of Iμ0=(3.477±0.002stat±0.067sys)×10−4/(s · m2) was found in good agreement with other experiments at LNGS. Combining the present result with those from previous experiments at LNGS the effective temperature coefficient αT,Lngs is determined to 0.93 ± 0.03. A fit of the temperature coefficients measured at various underground sites yields a kaon to pion ratio rK/π of 0.10 ± 0.03.
Published: 2016

46. Search of Neutrinoless Double Beta Decay with the GERDA Experiment

Author: Agostini, M, Allardt, M, Bakalyarov, AM, Balata, M, Barabanov, I, Baudis, L, Bauer, C, Becerici-Schmidt, N, Bellotti, E, Belogurov, S, Belyaev, ST, Benato, G, Bettini, A, Bezrukov, L, Bode, T, Borowicz, D, Brudanin, V, Brugnera, R, Budjáš, D, Caldwell, A, Cattadori, C, Chernogorov, A, D'Andrea, V, Demidova, EV, Domula, A, Doroshkevich, E, Egorov, V, Falkenstein, R, Fedorova, O, Freund, K, Frodyma, N, Gangapshev, A, Garfagnini, A, Gooch, C, Gotti, C, Grabmayr, P, Gurentsov, V, Gusev, K, Hampel, W, Hegai, A, Heisel, M, Hemmer, S, Heusser, G, Hoffmann, W, Hult, M, Inzhechik, LV, Ioannucci, L, Csáthy, J Janicksó, Jochum, J, Junker, M, Kazalov, V, Kihm, T, Kirpichnikov, IV, Kirsch, A, Klimenko, A, Knöpfle, KT, Kochetov, O, Kornoukhov, VN, Kuzminov, VV, Laubenstein, M, Lazzaro, A, Lebedev, VI, Lehnert, B, Liao, HY, Lindner, M, Lippi, I, Lubashevskiy, A, Lubsandorzhiev, B, Lutter, G, Macolino, C, Majorovits, B, Maneschg, W, Marissens, G, Medinaceli, E, Misiaszek, M, Moseev, P, Nemchenok, I, Nisi, S, Palioselitis, D, Panas, K, Pandola, L, Pelczar, K, Pessina, G, Pullia, A, Reissfelder, M, Riboldi, S, Rumyantseva, N, Sada, C, Salathe, M, Schmitt, C, Schneider, B, Schreiner, J, Schulz, O, Schwingenheuer, B, Schönert, S, Seitz, H, Selivalenko, O, Shevchik, E, Shirchenko, M, and Simgen, H
Subjects: neutrinoless double beta decay, T-1/2(0 nu), Ge-76, enriched Ge detectors
Abstract: The GERDA (GERmanium Detector Array) is an experiment for the search of neutrinoless double beta decay (0νββ) 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 2.4·1025 yr on the 0νββ 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 mee
Published: 2016

47. Search for neutrinoless double beta decay with the Gerda experiment: Phase II

Author: Agostini, M, Allardt, M, Bakalyarov, AM, Balata, M, Barabanov, I, Baudis, L, Bauer, C, Bellotti, E, Belogurov, S, Belyaev, ST, Benato, G, Bettini, A, Bezrukov, L, Bode, T, Borowicz, D, Brudanin, V, Brugnera, R, Caldwell, A, Cattadori, C, Chernogorov, A, D'Andrea, V, Demidova, EV, Di Marco, N, Domula, A, Doroshkevich, E, Egorov, V, Falkenstein, R, Frodyma, N, Gangapshev, A, Garfagnini, A, Gooch, C, Grabmayr, P, Gurentsov, V, Gusev, K, Hakenmüller, J, Hegai, A, Heisel, M, Hemmer, S, Hofmann, W, Hult, M, Inzhechik, LV, Janicskó Csáthy, J, Jochum, J, Junker, M, Kazalov, V, Kihm, T, Kirpichnikov, IV, Kirsch, A, Kish, A, Klimenko, A, Kneißl, R, Knöpfle, KT, Kochetov, O, Kornoukhov, VN, Kuzminov, VV, Laubenstein, M, Lazzaro, A, Lebedev, VI, Lehnert, B, Liao, HY, Lindner, M, Lippi, I, Lubashevskiy, A, Lubsandorzhiev, B, Lutter, G, Macolino, C, Majorovits, B, Maneschg, W, Medinaceli, E, Miloradovic, M, Mingazheva, R, Misiaszek, M, Moseev, P, Nemchenok, I, Palioselitis, D, Panas, K, Pandola, L, Pelczar, K, Pullia, A, Riboldi, S, Rumyantseva, N, Sada, C, Salamida, F, Salathe, M, Schmitt, C, Schneider, B, Schönert, S, Schreiner, J, Schulz, O, Schütz, AK, Schwingenheuer, B, Selivanenko, O, Shevchik, E, Shirchenko, M, Simgen, H, Smolnikov, A, Stanco, L, Vanhoefer, L, Vasenko, AA, and Veresnikova, A
Abstract: The GERmanium Detector Array (Gerda) experiment, located at the Gran Sasso underground laboratory in Italy, is built for the search of 0vββ decay in 76Ge. 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.yr with a background level of 10-2 cts/(keV.kg.yr). Gerda Phase I set a limit on the 0vββ decay of 76Ge of T1/20v > 2.1.1025 yr. In Phase II 35 kg of germanium detectors enriched in 76Ge are operated to reach an exposure of 100 kg.yr. The design goal is to reduce the background by one order of magnitude to reach the sensitivity for T1/20v = (1026) 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.yr exposure reached in June 2016.
Published: 2016

48. First results of GERDA Phase II

Author: Agostini, M, Allardt, M, Bakalyarov, AM, Balata, M, Barabanov, I, Baudis, L, Bauer, C, Bellotti, E, Belogurov, S, Belyaev, ST, Benato, G, Bettini, A, Bezrukov, L, Bode, T, Borowicz, D, Brudanin, V, Brugnera, R, Caldwell, A, Cattadori, C, Chernogorov, A, D'Andrea, V, Demidova, EV, Di Marco, N, Domula, A, Doroshkevich, E, Egorov, V, Falkenstein, R, Frodyma, N, Gangapshev, A, Garfagnini, A, Gooch, C, Grabmayr, P, Gurentsov, V, Gusev, K, Hakenmüller, J, Hegai, A, Heisel, M, Hemmer, S, Hofmann, W, Hult, M, Inzhechik, LV, Janicskó Csáthy, J, Jochum, J, Junker, M, Kazalov, V, Kihm, T, Kirpichnikov, IV, Kirsch, A, Kish, A, Klimenko, A, Kneißl, R, Knöpfle, KT, Kochetov, O, Kornoukhov, VN, Kuzminov, VV, Laubenstein, M, Lazzaro, A, Lebedev, VI, Lehnert, B, Liao, HY, Lindner, M, Lippi, I, Lubashevskiy, A, Lubsandorzhiev, B, Lutter, G, Macolino, C, Majorovits, B, Maneschg, W, Medinaceli, E, Miloradovic, M, Mingazheva, R, Misiaszek, M, Moseev, P, Nemchenok, I, Palioselitis, D, Panas, K, Pandola, L, Pelczar, K, Pullia, A, Riboldi, S, Rumyantseva, N, Sada, C, Salamida, F, Salathe, M, Schmitt, C, Schneider, B, Schönert, S, Schreiner, J, Schulz, O, Schütz, AK, Schwingenheuer, B, Selivanenko, O, Shevzik, E, Shirchenko, M, Simgen, H, Smolnikov, A, Stanco, L, Vanhoefer, L, Vasenko, AA, and Veresnikova, A
Abstract: The GErmanium Detector Array (Gerda) experiment, located at the Laboratori Nazionali del Gran Sass15, searches for the 0νββ decay of 76Ge. Gerda Phase II was started in December 2015, aiming to reach a sensitivity on the 0νββ decay half-life larger than 1026 yr in three yr of data taking with about 100 kg·yr exposure with background index of about 10-3 cts/(keV·kg·yr). The major upgrade of Phase II is the deployment of thirty newly produced Broad Energy Germanium 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. After 6 months of operation a first data release with 10.8 kg·yr exposure was performed, showing that the background goal has been achieved. A new lower limit on the 0νββ decay half life of 76Ge of 5.3·1025 yr (90% C.L.) has been set.
Published: 2016

49. Production, characterization and operation of $^{76}$Ge enriched BEGe detectors in GERDA

Author: Agostini, M., Allardt, M., Andreotti, E., Bakalyarov, A. M., Balata, M., Barabanov, I., Barros, N., Baudis, L., Bauer, C., Becerici-Schmidt, N., Bellotti, E., Belogurov, S., Belyaev, S. T., Benato, G., Bettini, A., Bezrukov, L., Bode, T., Borowicz, D., Brudanin, V., Brugnera, R., Budjas, D., Caldwel, A., Cattadori, C., Chernogorov, A., D'Andrea, V., Demidova, E. V., Domula, A., Egorov, V., Falkenstein, R., Freund, K., Frodyma, N., Gangapshev, A., Garfagnini, A., Gotti, C., Grabmayr, P., Gurentsov, V., Gusev, K., Hampel, W., Hegai, A., Heisel, M., Hemmer, S., Heusser, G., Hofmann, W., Hult, M., Inzhechik, L. V., Ioannucci, L., Csathy, J. Janicsko, Jochum, J., Junker, M., Kazalov, V., Kihm, T., Kirpichnikov, I. V., Kirsch, A., Klimenko, A., Knöpfle, K. T., Kochetov, O., Kornoukhov, V. N., Kuzminov, V. V., Laubenstein, M., Lazzaro, A., Lebedev, V. I., Lehnert, B., Liao, H. Y., Lindner, M., Lippi, I., Lubashevskiy, A., Lubsandorzhiev, B., Lutter, G., Macolino, C., Majorovits, B., Maneschg, W., Misiaszek, M., Nemchenok, I., Nisi, S., O'Shaughnessy, C., Palioselitis, D., 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., Ur, C. A., Vanhoefer, L., Vasenko, A. A., von Sturm, K., Wagner, V., Walter, M., Wegmann, A., Wester, T., Wilsenach, H., Wojcik, M., Yanovich, E., Zavarise, P., Zhitnikov, I., Zhukov, S. V., Zinatulina, D., Zuber, K., and Zuzel, G.
Subjects: Physics - Instrumentation and Detectors, High Energy Physics - Experiment, Nuclear Experiment
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., Comment: 23 pages, 21 figures
Published: 2014
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50. Results on ββ decay with emission of two neutrinos or Majorons in 76Ge from GERDA Phase I: GERDA Collaboration

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

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