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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. The cross section functions for neutron induced reactions with Rhenium in the energy range 13.0–19.5 MeV

Author: Jovančević N., Daraban L., Stroh H., Oberstedt S., Hult M., Bonaldi C., Geerts W., Hambsch F.-J., Lutter G., Marissens G., and Vidali M.
Subjects: Physics, QC1-999
Abstract: The technique for measuring neutron activation cross-sections using wide energy neutron beams (NAXSUN) was recently developed at JRC-Geel . This method is based on the detection of the gamma activity induced by the activation of the samples in different but overlapping neutron fields and following an unfolding procedure. In the present work, measurements of the cross-section functions by the NAXSUN technique for the (n,a), (n,2n), (n,p) and (n,3n) reactions on rhenium isotopes 185Re and 187Re were performed. The results are the first experimental data for the mentioned reaction cross-sections in the energy range 13.0–19.5 MeV. The obtained data are of interest for possible applications of Re in nuclear technology and medicine.
Published: 2017
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9. A new certified reference material IAEA-465 for radionuclides in Baltic Sea sediment

Author: Pham, M.K., Aust, M.-O., Bartocci, J., Blinova, O., Carvalho, F.P., Chamizo, E., Cook, M., Degering, D., Fujak, M., Gascó, C., Gurriaran, R., Jobbágy, V., Herrmann, J., Hult, M., Ilchmann, C., La Rosa, J., Laubenstein, M., Lee, S.-H., Levy, I., Mas, J.L., Mc-Ginnity, P., Mietelski, J.W., Morimoto, T., Nakano, M., Nielsen, S.P., Nour, S., Osvath, I., Povinec, P.P., Rieth, U., Schikowski, J., Smedley, P., Suplinska, M., Sýkora, I., Van Beek, P., Vartti, V.-P., and Zalewska, T.
Published: 2024
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10. 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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11. New limits on double-beta decay of $^{190}$Pt and $^{198}$Pt

Author: Danevich, F. A., Hult, M., Junghans, A., Kasperovych, D. V., Kropivyansky, B. N., Lutter, G., Marissens, G., Polischuk, O. G., Romaniuk, M. V., Stroh, H., Tessalina, S., Tretyak, V. I., and Ware, B.
Subjects: Nuclear Experiment
Abstract: A search for double-beta decay of $^{190}$Pt and $^{198}$Pt with emission of $\gamma$-ray quanta was realized at the HADES underground laboratory with a 148 g platinum sample measured by two ultralow-background HPGe detectors over 8946 h. The isotopic composition of the platinum sample has been measured with high precision using inductively coupled plasma mass spectrometry. New lower limits for the half-lives of $^{190}$Pt relative to different channels and modes of the decays were set on the level of $\lim T_{1/2}\sim 10^{14}-10^{16}$ yr. A possible exact resonant $0\nu KN$ transition to the 1,2 1326.9 keV level of $^{190}$Os is limited for the first time as $T_{1/2} \geq 2.5 \times10^{16}$ yr. A new lower limit on the double-beta decay of $^{198}$Pt to the first excited level of $^{198}$Hg was set as $T_{1/2} \geq 3.2\times10^{19}$ yr, one order of magnitude higher than the limit obtained in the previous experiment., Comment: 23 pages, 11 figures, 4 tables
Published: 2022
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12. Constraints on partial half-lives of Ce-136 and Ce-138 double electron captures

Author: Lehnert, B., Hult, M., Lutter, G., Marissens, G., Oberstedt, S., Stroh, H., Kotila, J., Oberstedt, A., and Zuber, K.
Subjects: Nuclear Experiment
Abstract: The gamma-ray emissions from a radiopure cerium-bromide crystal with a mass of 4381 g were measured for a total of 497.4 d by means of high-resolution gamma-ray spectrometry in the HADES underground laboratory at a depth of 500 m.w.e. A search for 0/2nee and 0/2neb+ double beta decay transitions of Ce-136 and Ce-138 was performed using Bayesian analysis techniques. No signals were observed for a total of 35 investigated decay modes. 90% credibility limits were set in the order of 1e18-1e19 a. Existing constraints from a cerium oxide powder measurement were tested with a different cerium compound and half-life limits could be improved for most of the decay modes. The most likely accessible decay mode of the Ce-136 2nee transition into the 0+1 state of Ba-136 results in a new best 90% credibility limit of 5.0e18 a.
Published: 2021
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13. Constraints on partial half-lives of Ce136 and Ce138 double electron captures

Author: Lehnert, B, Hult, M, Lutter, G, Marissens, G, Oberstedt, S, Stroh, H, Kotila, J, Oberstedt, A, and Zuber, K
Subjects: Atomic, Molecular, Nuclear, Particle and Plasma Physics, Nuclear & Particles Physics
Abstract: The γ-ray emissions from a radiopure cerium-bromide crystal with a mass of 4381 g were measured for a total of 497.4 d by means of high-resolution γ-ray spectrometry in the HADES underground laboratory at a depth of 500 m.w.e. A search for 0/2νϵϵ and 0/2νϵβ+ double beta decay transitions of Ce136 and Ce138 was performed using Bayesian analysis techniques. No signals were observed for a total of 35 investigated decay modes. 90% credibility limits were set in the order of 1018-1019 yr. Existing constraints from a cerium oxide powder measurement were tested with a different cerium compound and half-life limits could be improved for most of the decay modes. The most likely accessible decay mode of the Ce136 2νϵϵ transition into the 01+ state of Ba136 results in a new best 90% credibility limit of 5.0×1018 yr.
Published: 2022

14. 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

15. 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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16. 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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17. 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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18. Decay scheme of 50V

Author: Danevich, F. A., Hult, M., Kasperovych, D. V., Klavdiienko, V. R., Lutter, G., Marissens, G., Polischuk, O. G., and Tretyak, V. I.
Subjects: Nuclear Experiment
Abstract: Investigation of the $^{50}$V electron-capture to the $2^+$ 1553.8 keV level of $^{50}$Ti and search for $\beta^-$ decay of $^{50}$V to the $2^+$ 783.3 keV level of $^{50}$Cr (both those decays are fourfold forbidden with $\Delta J^{\Delta \pi}=4^+$) have been performed using a vanadium sample of natural isotopic abundance with mass of 955 g. The measurements were conducted with the help of an ultra low-background HPGe-detector system located 225 m underground in the laboratory HADES (Belgium). The measured value of the half-life of $^{50}$V for electron capture was $T^{\mathrm{EC}}_{1/2}=(2.77^{+0.20}_{-0.19})\times 10^{17}$ yr. The $\beta^-$-decay branch was not detected and the corresponding lower bound of the half-life was $T^{\beta}_{1/2}\geq 8.9\times 10^{18}$ yr at the 90\% confidence level., Comment: 20 pages, 9 figures, 7 tables, 27 references
Published: 2020

19. The first search for bosonic super-WIMPs with masses up to 1 MeV/c$^2$ with GERDA

Author: GERDA collaboration, Agostini, M., Bakalyarov, A. M., Balata, M., Barabanov, I., Baudis, L., Bauer, C., Bellotti, E., Belogurov, S., Bettini, A., Bezrukov, L., Borowicz, D., Bossio, E., Bothe, V., Brudanin, V., Brugnera, R., Caldwell, A., Cattadori, C., Chernogorov, A., Comellato, T., D'Andrea, V., Demidova, E. V., Di Marco, N., Doroshkevich, E., Egorov, V., Fischer, F., Fomina, M., Gangapshev, A., Garfagnini, A., Gooch, C., Grabmayr, P., Gurentsov, V., Gusev, K., Hakenmüller, J., Hemmer, S., Hiller, R., Hofmann, W., Hult, M., Inzhechik, L. V., Csáthy, J. Janicskó, Jochum, J., Junker, M., Kazalov, V., Kermaïdic, Y., Khushbakht, H., Kihm, T., Kirpichnikov, I. V., Klimenko, A., Kneißl, R., Knöpfle, K. T., Kochetov, O., Kornoukhov, V. N., Krause, P., Kuzminov, V. V., Laubenstein, M., Lazzaro, A., Lindner, M., Lippi, I., Lubashevskiy, A., Lubsandorzhiev, B., Lutter, G., Macolino, C., Majorovits, B., Maneschg, W., Miloradovic, M., Mingazheva, R., Misiaszek, M., Moseev, P., Nemchenok, I., Panas, K., Pandola, L., Pelczar, K., Pertoldi, L., Piseri, P., Pullia, A., Ransom, C., Rauscher, L., Riboldi, S., Rumyantseva, N., Sada, C., Salamida, F., Schönert, S., Schreiner, J., Schütt, M., Schütz, A-K., Schulz, O., Schwarz, M., Schwingenheuer, B., Selivanenko, O., Shevchik, E., Shirchenko, M., Simgen, H., Smolnikov, A., Stukov, D., Vasenko, A. A., Veresnikova, A., Vignoli, C., von Sturm, K., Wester, T., Wiesinger, C., Wojcik, M., Yanovich, E., Zatschler, B., Zhitnikov, I., Zhukov, S. V., Zinatulina, D., Zschocke, A., Zsigmond, A. J., and Zuzel, K. Zuber G.
Subjects: High Energy Physics - Experiment, Nuclear Experiment
Abstract: We present the first search for bosonic super-WIMPs as keV-scale dark matter candidates performed with the GERDA experiment. GERDA is a neutrinoless double-beta decay experiment which operates high-purity germanium detectors enriched in $^{76}$Ge in an ultra-low background environment at the Laboratori Nazionali del Gran Sasso (LNGS) of INFN in Italy. Searches were performed for pseudoscalar and vector particles in the mass region from 60 keV/c$^2$ to 1 MeV/c$^2$. No evidence for a dark matter signal was observed, and the most stringent constraints on the couplings of super-WIMPs with masses above 120 keV/c$^2$ have been set. As an example, at a mass of 150 keV/c$^2$ the most stringent direct limits on the dimensionless couplings of axion-like particles and dark photons to electrons of $g_{ae} < 3 \cdot 10^{-12}$ and ${\alpha'}/{\alpha} < 6.5 \cdot 10^{-24}$ at 90% credible interval, respectively, were obtained., Comment: 6 pages, 3 figures, submitted to Physical Review Letters, added list of authors, updated ref. [21]
Published: 2020
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20. First search for $2\varepsilon$ and $\varepsilon\beta^+$ decay of $^{174}$Hf

Author: Danevich, F. A., Hult, M., Kasperovych, D. V., Kovtun, G. P., Kovtun, K. V., Lutter, G., Marissens, G., Polischuk, O. G., Stetsenko, S. P., and Tretyak, V. I.
Subjects: Nuclear Experiment
Abstract: The first ever search for $2\varepsilon$ and $\varepsilon\beta^+$ decay of $^{174}$Hf was realized using a high-pure sample of hafnium (with mass 179.8 g) and the ultra low-background HPGe-detector system located 225 m underground. After 75 days of data taking no indication of the double beta decay transitions could be detected but lower limits for the half-lives of the different channels and modes of the decays were set on the level of $\lim T_{1/2}\sim 10^{16}-10^{18}$ a., Comment: 16 pages, 9 figures, 3 Tables
Published: 2020
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21. 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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22. Quantification of uranium-238 in environmental samples using gamma-ray spectrometry

Author: Yeltepe E., Pommé S., González de Orduña R., Andreotti E., and Hult M.
Subjects: Physics, QC1-999
Abstract: A large number of environmental samples are routinely measured world-wide using gamma-ray spectrometry some of its assets being easy sample preparation and comprehensive data for many radionu-clides in one analysis. Although other techniques can be considered more suitable for analysing 238U in environmental samples, it is also routinely done by gamma-ray spectrometry. One mainly uses γ-ray emissions following the decay of the first daughter, 234Th, for determining the 238U activity. However, the low-energy gamma-rays at 63 keV and 92.5 keV are very difficult to quantify in a robust way due to high attenuation and interferences. This paper quantifies parameters affecting the possibility of making robust quantification of 238U via 234Th using gamma-ray spectrometry. It addresses the use of correct decay data, suitable detectors, optimised sample size, enhanced spectral amplification, correction for peak interferences and control of background.
Published: 2012
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23. First search for $\alpha$ decays of naturally occurring Hf nuclides with emission of $\gamma$ quanta

Author: Danevich, F. A., Hult, M., Kasperovych, D. V., Kovtun, G. P., Kovtun, K. V., Lutter, G., Marissens, G., Polischuk, O. G., Stetsenko, S. P., and Tretyak, V. I.
Subjects: Nuclear Experiment
Abstract: The first ever search for $\alpha$ decays to the first excited state in Yb was performed for six isotopes of hafnium (174, 176, 177, 178, 179, 180) using a high purity Hf-sample of natural isotopic abundance with a mass of 179.8 g. For $^{179}$Hf, also $\alpha$ decay to the ground state of $^{175}$Yb was searched for thanks to the $\beta$-instability of the daughter nuclide $^{175}$Yb. The measurements were conducted using an ultra low-background HPGe-detector system located 225 m underground. After 75 d of data taking no decays were detected but lower bounds for the half-lives of the decays were derived on the level of $\lim T_{1/2}\sim 10^{15}-10^{18}$~a. The decay with the shortest half-life based on theoretical calculation is the decay of $^{174}$Hf to the first $2^+$ 84.3~keV excited level of $^{170}$Yb. The experimental lower bound was found to be $T_{1/2}\geq 3.3\times 10^{15}$ a., Comment: 19 pages, 7 figures, 7 tables
Published: 2019
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24. 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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25. 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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26. 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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27. 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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28. 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

29. 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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30. 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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31. 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

32. 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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33. 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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34. 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

35. 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

36. 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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37. Double Beta Decays into Excited States in $^{110}$Pd and $^{102}$Pd

Author: Lehnert, B., Andreotti, E., Degering, D., Hult, M., Laubenstein, M., Wester, T., and Zuber, K.
Subjects: Nuclear Experiment
Abstract: A search for double beta decays of $^{110}$Pd and $^{102}$Pd into excited states of the daughter nuclides has been performed using three ultra-low background gamma-spectrometry measurements in the Felsenkeller laboratory, Germany, the HADES laboratory, Belgium and at the LNGS, Italy. The combined Bayesian analysis of the three measurements sets improved half-life limits for the $2\nu\beta\beta$ and $0\nu\beta\beta$ decay modes of the $2^+_1$, $0^+_1$ and $2^+_2$ transitions in $^{110}$Pd to $2.9\cdot10^{20}$ yr, $4.0\cdot10^{20}$ yr and $3.0\cdot10^{20}$ yr respectively and in $^{102}$Pd to $7.6\cdot10^{18}$ yr, $8.8\cdot10^{18}$ yr and $1.4\cdot10^{19}$ yr respectively with 90% credibility.
Published: 2016
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38. 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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39. 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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40. The large enriched germanium experiment for neutrinoless double beta decay (LEGEND)

Author: Abgrall, N, Abramov, A, Abrosimov, N, Abt, I, Agostini, M, Agartioglu, M, Ajjaq, A, Alvis, SI, Avignone, FT, Bai, X, Balata, M, Barabanov, I, Barabash, AS, Barton, PJ, Baudis, L, Bezrukov, L, Bode, T, Bolozdynya, A, Borowicz, D, Boston, A, Boston, H, Boyd, STP, Breier, R, Brudanin, V, Brugnera, R, Busch, M, Buuck, M, Caldwell, A, Caldwell, TS, Camellato, T, Carpenter, M, Cattadori, C, Cederkäll, J, Chan, Y-D, Chen, S, Chernogorov, A, Christofferson, CD, Chu, P-H, Cooper, RJ, Cuesta, C, Demidova, EV, Deng, Z, Deniz, M, Detwiler, JA, Di Marco, N, Domula, A, Du, Q, Efremenko, Yu, Egorov, V, Elliott, SR, Fields, D, Fischer, F, Galindo-Uribarri, A, Gangapshev, A, Garfagnini, A, Gilliss, T, Giordano, M, Giovanetti, GK, Gold, M, Golubev, P, Gooch, C, Grabmayr, P, Green, MP, Gruszko, J, Guinn, IS, Guiseppe, VE, Gurentsov, V, Gurov, Y, Gusev, K, Hakenmüeller, J, Harkness-Brennan, L, Harvey, ZR, Haufe, CR, Hauertmann, L, Heglund, D, Hehn, L, Heinz, A, Hiller, R, Hinton, J, Hodak, R, Hofmann, W, Howard, S, Howe, MA, Hult, M, Inzhechik, LV, Csáthy, J Janicskó, Janssens, R, Ješkovský, M, Jochum, J, Johansson, HT, Judson, D, Junker, M, Kaizer, J, Kang, K, Kazalov, V, Kermadic, Y, Kiessling, F, Kirsch, A, Kish, A, and Klimenko, A
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, physics.ins-det, hep-ex, nucl-ex
Abstract: The observation of neutrinoless double-beta decay (0νββ) would show that lepton number is violated, reveal that neu-trinos 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 ∼0.1 count /(FWHM·t·yr) in the region of the signal. The current generation 76Ge 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 0νββ signal region of all 0νββ experiments. Building on this success, the LEGEND collaboration has been formed to pursue a tonne-scale 76Ge experiment. The collaboration aims to develop a phased 0νββ experimental program with discovery potential at a half-life approaching or at 1028 years, using existing resources as appropriate to expedite physics results.
Published: 2017

41. 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

42. 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

43. 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

44. 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

45. 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

46. 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

47. 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

48. 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

49. Reference material for natural radionuclides in glass designed for underground experiments

Author: Povinec, P. P., Pham, M. K., Busto, J., Cerna, C., Degering, D., Hamajima, Y., Holy, K., Hult, M., Jeskovsky, M., Koehler, M., Kovacik, A., Laubenstein, M., Loaiza, P., Mamedov, F., Marquet, C., Mott, J., Mullerova, M., Perrot, F., Piquemal, F., Reyss, J. -L., Saakyan, R., Simgen, H., Soule, B., Stanicek, J., Sykora, I., and Stekl, I.
Subjects: Physics - Instrumentation and Detectors, Nuclear Experiment
Abstract: A reference material designed for the determination of natural radionuclides in solid samples (glass pellets) is described and the results of certification are presented. The material has been certified for 7 natural radionuclides (40K, 226Ra, 228Ra, 228Th, 232Th, 235U and 238U). An information value is given for 210Pb. Radon (222Rn) emanation experiments showed results comparable within participating laboratories, however, the number of data and precision was too low to carry out a certification process. The reference material may be used for quality management of analytical laboratories engaged in the high-sensitive analysis of radionuclides in the construction materials of detectors placed in ultra low background underground laboratories., Comment: 13 pages 6 tables, 3 figures
Published: 2015

50. $2\nu\beta\beta$ 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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