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1. 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

2. 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

3. 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

4. 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

5. 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

6. 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

7. 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

8. 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

9. 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

10. 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

11. 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

12. Flux modulations seen by the muon veto of the Gerda experiment

Author

collaboration, GERDA, Agostini, M, Allardt, M, Bakalyarov, AM, Balata, M, Barabanov, I, Barros, N, Baudis, L, Bauer, C, Becerici-Schmidt, N, Bellotti, E, Belogurov, S, Belyaev, ST, Benato, G, Bettini, A, Bezrukov, L, Bode, T, Borowicz, D, Brudanin, V, Brugnera, R, Caldwell, A, Cattadori, C, Chernogorov, A, D’Andrea, V, Demidova, EV, di Vacri, A, Domula, A, Doroshkevich, E, Egorov, V, Falkenstein, R, Fedorova, O, Freund, K, Frodyma, N, Gangapshev, A, Garfagnini, A, Grabmayr, P, Gurentsov, V, Gusev, K, Hegai, A, Heisel, M, Hemmer, S, Hofmann, W, Hult, M, Inzhechik, LV, Ioannucci, L, Cs’athy, J Janicsk’o, Jochum, J, Junker, M, Kazalov, V, Kihm, T, Kirpichnikov, IV, Kirsch, A, Klimenko, A, Knapp, M, Knöpfle, KT, Kochetov, O, Kornoukhov, VN, Kuzminov, VV, Laubenstein, M, Lazzaro, A, Lebedev, VI, Lehnert, B, Liao, HY, Lindner, M, Lippi, I, Lubashevskiy, A, Lubsandorzhiev, B, Lutter, G, Macolino, C, Majorovits, B, Maneschg, W, Medinaceli, E, Misiaszek, M, Moseev, P, Nemchenok, I, Palioselitis, D, Panas, K, Pandola, L, Pelczar, K, Pullia, A, Riboldi, S, Ritter, F, Rumyantseva, N, Sada, C, Salathe, M, Schmitt, C, Schneider, B, Schönert, S, Schreiner, J, Schütz, A-K, Schulz, O, Schwingenheuer, B, Selivanenko, O, Shevchik, E, Shirchenko, M, Simgen, H, Smolnikov, A, Stanco, L, Stepaniuk, M, and Strecker, H

Subjects
Water cherenkov detector, Underground experiment, Cosmic rays, Muon interaction, physics.ins-det, hep-ex, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Nuclear & Particles Physics
Abstract

The GERDA experiment at LNGS of INFN is equipped with an active muon veto. The main part of the system is a water Cherenkov veto with 66 PMTs in the water tank surrounding the GERDA cryostat. The muon flux recorded by this veto shows a seasonal modulation. Two causes have been identified: (i) secondary muons from the CNGS neutrino beam (2.2%) and (ii) a temperature modulation of the atmosphere (1.4%). A mean cosmic muon rate of Iμ0=(3.477±0.002stat±0.067sys)×10−4/(s · m2) was found in good agreement with other experiments at LNGS. Combining the present result with those from previous experiments at LNGS the effective temperature coefficient αT,Lngs is determined to 0.93 ± 0.03. A fit of the temperature coefficients measured at various underground sites yields a kaon to pion ratio rK/π of 0.10 ± 0.03.

Published
2016

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

Author

Agostini, M, Balata, M, D'Andrea, V, di Vacri, A, Ioannucci, L, Junker, M, Laubenstein, M, Macolino, C, Pandola, L, Borowicz, D, Frodyma, N, Misiaszek, M, Panas, K, Pelczar, K, Wojcik, M, Zuzel, G, Allardt, M, Barros, N, Domula, A, Lehnert, B, Schneider, B, Wester, T, Wilsenach, H, Zuber, K, Brudanin, V, Egorov, V, Gusev, K, Klimenko, A, Kochetov, O, Lubashevskiy, A, Nemchenok, I, Rumyantseva, N, Shevchik, E, Shirchenko, M, Zhitnikov, I, Zinatulina, D, Hult, M, Lutter, G, Bauer, C, Gangapshev, A, Heisel, M, Hofmann, W, Kihm, T, Kirsch, A, Knöpfle, KT, Lindner, M, Maneschg, W, Salathe, M, Schreiner, J, Schwingenheuer, B, Simgen, H, Smolnikov, A, Stepaniuk, M, Strecker, H, Wagner, V, Wegmann, A, Bellotti, E, Cattadori, C, Pullia, A, Riboldi, S, Barabanov, I, Belogurov, S, Bezrukov, L, Doroshkevich, E, Fedorova, O, Gurentsov, V, Inzhechik, LV, Kazalov, V, Kornoukhov, VN, Kuzminov, VV, Lubsandorzhiev, B, Moseev, P, Selivanenko, O, Veresnikova, A, Yanovich, E, Chernogorov, A, Demidova, EV, Kirpichnikov, IV, Vasenko, AA, Bakalyarov, AM, Belyaev, ST, Lebedev, VI, Zhukov, SV, Becerici-Schmidt, N, Caldwell, A, Liao, HY, Majorovits, B, Palioselitis, D, Schulz, O, Vanhoefer, L, Bode, T, Janicsk'o Cs'athy, J, Lazzaro, A, Schönert, S, Wiesinger, C, Bettini, A, Brugnera, R, Garfagnini, A, Hemmer, S, and Medinaceli, E

Subjects
Water cherenkov detector, Underground experiment, Cosmic rays, Muon interaction, physics.ins-det, hep-ex, Nuclear & Particles Physics, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics
Abstract

The GERDA experiment at LNGS of INFN is equipped with an active muon veto. The main part of the system is a water Cherenkov veto with 66 PMTs in the water tank surrounding the GERDA cryostat. The muon flux recorded by this veto shows a seasonal modulation. Two causes have been identified: (i) secondary muons from the CNGS neutrino beam (2.2%) and (ii) a temperature modulation of the atmosphere (1.4%). A mean cosmic muon rate of Iμ0=(3.477±0.002stat±0.067sys)×10−4/(s · m2) was found in good agreement with other experiments at LNGS. Combining the present result with those from previous experiments at LNGS the effective temperature coefficient αT,Lngs is determined to 0.93 ± 0.03. A fit of the temperature coefficients measured at various underground sites yields a kaon to pion ratio rK/π of 0.10 ± 0.03.

Published
2016

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

Author

Agostini, M, Allardt, M, Bakalyarov, AM, Balata, M, Barabanov, I, Baudis, L, Bauer, C, Becerici-Schmidt, N, Bellotti, E, Belogurov, S, Belyaev, ST, Benato, G, Bettini, A, Bezrukov, L, Bode, T, Borowicz, D, Brudanin, V, Brugnera, R, Budjáš, D, Caldwell, A, Cattadori, C, Chernogorov, A, D'Andrea, V, Demidova, EV, Domula, A, Doroshkevich, E, Egorov, V, Falkenstein, R, Fedorova, O, Freund, K, Frodyma, N, Gangapshev, A, Garfagnini, A, Gooch, C, Gotti, C, Grabmayr, P, Gurentsov, V, Gusev, K, Hampel, W, Hegai, A, Heisel, M, Hemmer, S, Heusser, G, Hoffmann, W, Hult, M, Inzhechik, LV, Ioannucci, L, Csáthy, J Janicksó, Jochum, J, Junker, M, Kazalov, V, Kihm, T, Kirpichnikov, IV, Kirsch, A, Klimenko, A, Knöpfle, KT, Kochetov, O, Kornoukhov, VN, Kuzminov, VV, Laubenstein, M, Lazzaro, A, Lebedev, VI, Lehnert, B, Liao, HY, Lindner, M, Lippi, I, Lubashevskiy, A, Lubsandorzhiev, B, Lutter, G, Macolino, C, Majorovits, B, Maneschg, W, Marissens, G, Medinaceli, E, Misiaszek, M, Moseev, P, Nemchenok, I, Nisi, S, Palioselitis, D, Panas, K, Pandola, L, Pelczar, K, Pessina, G, Pullia, A, Reissfelder, M, Riboldi, S, Rumyantseva, N, Sada, C, Salathe, M, Schmitt, C, Schneider, B, Schreiner, J, Schulz, O, Schwingenheuer, B, Schönert, S, Seitz, H, Selivalenko, O, Shevchik, E, Shirchenko, M, and Simgen, H

Subjects
neutrinoless double beta decay, T-1/2(0 nu), Ge-76, enriched Ge detectors
Abstract

The GERDA (GERmanium Detector Array) is an experiment for the search of neutrinoless double beta decay (0νββ) in 76Ge, located at Laboratori Nazionali del Gran Sasso of INFN (Italy). In the first phase of the experiment, a 90% confidence level (C.L.) sensitivity of 2.4·1025 yr on the 0νββ decay half-life was achieved with a 21.6 kg·yr exposure and an unprecedented background index in the region of interest of 10-2 counts/(keV·kg·yr). No excess of signal events was found, and an experimental lower limit on the half-life of 2.1 · 1025 yr (90% C.L.) was established. Correspondingly, the limit on the effective Majorana neutrino mass is mee

Published
2016

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

Author

Agostini, M, Allardt, M, Bakalyarov, AM, Balata, M, Barabanov, I, Baudis, L, Bauer, C, Bellotti, E, Belogurov, S, Belyaev, ST, Benato, G, Bettini, A, Bezrukov, L, Bode, T, Borowicz, D, Brudanin, V, Brugnera, R, Caldwell, A, Cattadori, C, Chernogorov, A, D'Andrea, V, Demidova, EV, Di Marco, N, Domula, A, Doroshkevich, E, Egorov, V, Falkenstein, R, Frodyma, N, Gangapshev, A, Garfagnini, A, Gooch, C, Grabmayr, P, Gurentsov, V, Gusev, K, Hakenmüller, J, Hegai, A, Heisel, M, Hemmer, S, Hofmann, W, Hult, M, Inzhechik, LV, Janicskó Csáthy, J, Jochum, J, Junker, M, Kazalov, V, Kihm, T, Kirpichnikov, IV, Kirsch, A, Kish, A, Klimenko, A, Kneißl, R, Knöpfle, KT, Kochetov, O, Kornoukhov, VN, Kuzminov, VV, Laubenstein, M, Lazzaro, A, Lebedev, VI, Lehnert, B, Liao, HY, Lindner, M, Lippi, I, Lubashevskiy, A, Lubsandorzhiev, B, Lutter, G, Macolino, C, Majorovits, B, Maneschg, W, Medinaceli, E, Miloradovic, M, Mingazheva, R, Misiaszek, M, Moseev, P, Nemchenok, I, Palioselitis, D, Panas, K, Pandola, L, Pelczar, K, Pullia, A, Riboldi, S, Rumyantseva, N, Sada, C, Salamida, F, Salathe, M, Schmitt, C, Schneider, B, Schönert, S, Schreiner, J, Schulz, O, Schütz, AK, Schwingenheuer, B, Selivanenko, O, Shevchik, E, Shirchenko, M, Simgen, H, Smolnikov, A, Stanco, L, Vanhoefer, L, Vasenko, AA, and Veresnikova, A

Abstract

The GERmanium Detector Array (Gerda) experiment, located at the Gran Sasso underground laboratory in Italy, is built for the search of 0vββ decay in 76Ge. Gerda operates bare high purity germanium detectors submersed in liquid Argon (LAr). Phase I of the experiment was completed reaching an exposure of about 21 kg.yr with a background level of 10-2 cts/(keV.kg.yr). Gerda Phase I set a limit on the 0vββ decay of 76Ge of T1/20v > 2.1.1025 yr. In Phase II 35 kg of germanium detectors enriched in 76Ge are operated to reach an exposure of 100 kg.yr. The design goal is to reduce the background by one order of magnitude to reach the sensitivity for T1/20v = (1026) yr. The Phase II setup comprises thirty newly produced Broad Energy Germanium (BEGe) detectors. They contribute to the background reduction with better energy resolution and enhanced pulse shape discrimination. To achieve the necessary background reduction, the setup was complemented with LAr veto. The hardware upgrade for Phase II was finished and all detectors were deployed in December 2015. We present the first results of Phase II with 10.8 kg.yr exposure reached in June 2016.

Published
2016

16. First results of GERDA Phase II

Author

Agostini, M, Allardt, M, Bakalyarov, AM, Balata, M, Barabanov, I, Baudis, L, Bauer, C, Bellotti, E, Belogurov, S, Belyaev, ST, Benato, G, Bettini, A, Bezrukov, L, Bode, T, Borowicz, D, Brudanin, V, Brugnera, R, Caldwell, A, Cattadori, C, Chernogorov, A, D'Andrea, V, Demidova, EV, Di Marco, N, Domula, A, Doroshkevich, E, Egorov, V, Falkenstein, R, Frodyma, N, Gangapshev, A, Garfagnini, A, Gooch, C, Grabmayr, P, Gurentsov, V, Gusev, K, Hakenmüller, J, Hegai, A, Heisel, M, Hemmer, S, Hofmann, W, Hult, M, Inzhechik, LV, Janicskó Csáthy, J, Jochum, J, Junker, M, Kazalov, V, Kihm, T, Kirpichnikov, IV, Kirsch, A, Kish, A, Klimenko, A, Kneißl, R, Knöpfle, KT, Kochetov, O, Kornoukhov, VN, Kuzminov, VV, Laubenstein, M, Lazzaro, A, Lebedev, VI, Lehnert, B, Liao, HY, Lindner, M, Lippi, I, Lubashevskiy, A, Lubsandorzhiev, B, Lutter, G, Macolino, C, Majorovits, B, Maneschg, W, Medinaceli, E, Miloradovic, M, Mingazheva, R, Misiaszek, M, Moseev, P, Nemchenok, I, Palioselitis, D, Panas, K, Pandola, L, Pelczar, K, Pullia, A, Riboldi, S, Rumyantseva, N, Sada, C, Salamida, F, Salathe, M, Schmitt, C, Schneider, B, Schönert, S, Schreiner, J, Schulz, O, Schütz, AK, Schwingenheuer, B, Selivanenko, O, Shevzik, E, Shirchenko, M, Simgen, H, Smolnikov, A, Stanco, L, Vanhoefer, L, Vasenko, AA, and Veresnikova, A

Abstract

The GErmanium Detector Array (Gerda) experiment, located at the Laboratori Nazionali del Gran Sass15, searches for the 0νββ decay of 76Ge. Gerda Phase II was started in December 2015, aiming to reach a sensitivity on the 0νββ decay half-life larger than 1026 yr in three yr of data taking with about 100 kg·yr exposure with background index of about 10-3 cts/(keV·kg·yr). The major upgrade of Phase II is the deployment of thirty newly produced Broad Energy Germanium detectors. They contribute to the background reduction with better energy resolution and enhanced pulse shape discrimination. To achieve the necessary background reduction, the setup was complemented with LAr veto. After 6 months of operation a first data release with 10.8 kg·yr exposure was performed, showing that the background goal has been achieved. A new lower limit on the 0νββ decay half life of 76Ge of 5.3·1025 yr (90% C.L.) has been set.

Published
2016

17. Results on ββ decay with emission of two neutrinos or Majorons in 76Ge from GERDA Phase I: GERDA Collaboration

Author

GERDA Collaboration, Agostini, M, Allardt, M, Bakalyarov, AM, Balata, M, Barabanov, I, Barros, N, Baudis, L, Bauer, C, Becerici-Schmidt, N, Bellotti, E, Belogurov, S, Belyaev, ST, Benato, G, Bettini, A, Bezrukov, L, Bode, T, Borowicz, D, Brudanin, V, Brugnera, R, Budjáš, D, Caldwell, A, Cattadori, C, Chernogorov, A, D’Andrea, V, Demidova, EV, di Vacri, A, Domula, A, Doroshkevich, E, Egorov, V, Falkenstein, R, Fedorova, O, Freund, K, Frodyma, N, Gangapshev, A, Garfagnini, A, Grabmayr, P, Gurentsov, V, Gusev, K, Hegai, A, Heisel, M, Hemmer, S, Heusser, G, Hofmann, W, Hult, M, Inzhechik, LV, Csáthy, JJ, Jochum, J, Junker, M, Kazalov, V, Kihm, T, Kirpichnikov, IV, Kirsch, A, Klimenko, A, Knöpfle, KT, Kochetov, O, Kornoukhov, VN, Kuzminov, VV, Laubenstein, M, Lazzaro, A, Lebedev, VI, Lehnert, B, Liao, HY, Lindner, M, Lippi, I, Lubashevskiy, A, Lubsandorzhiev, B, Lutter, G, Macolino, C, Majorovits, B, Maneschg, W, Medinaceli, E, Misiaszek, M, Moseev, P, Nemchenok, I, Palioselitis, D, Panas, K, Pandola, L, Pelczar, K, Pullia, A, Riboldi, S, Rumyantseva, N, Sada, C, Salathe, M, Schmitt, C, Schneider, B, Schönert, S, Schreiner, J, Schütz, AK, Schulz, O, Schwingenheuer, B, Selivanenko, O, Shirchenko, M, Simgen, H, Smolnikov, A, Stanco, L, Stepaniuk, M, Ur, CA, Vanhoefer, L, and Vasenko, AA

Subjects
nucl-ex, physics.ins-det, Nuclear & Particles Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics
Abstract

A search for neutrinoless ββ decay processes accompanied with Majoron emission has been performed using data collected during Phase I of the GERmanium Detector Array (GERDA) experiment at the Laboratori Nazionali del Gran Sasso of INFN (Italy). Processes with spectral indices n = 1, 2, 3, 7 were searched for. No signals were found and lower limits of the order of 1023 yr on their half-lives were derived, yielding substantially improved results compared to previous experiments with 76Ge. A new result for the half-life of the neutrino-accompanied ββ decay of 76Ge with significantly reduced uncertainties is also given, resulting in (Formula presented.) yr.

Published
2015

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

Author

GERDA Collaboration, Agostini, M, Allardt, M, Bakalyarov, AM, Balata, M, Barabanov, I, Barros, N, Baudis, L, Bauer, C, Becerici-Schmidt, N, Bellotti, E, Belogurov, S, Belyaev, ST, Benato, G, Bettini, A, Bezrukov, L, Bode, T, Borowicz, D, Brudanin, V, Brugnera, R, Budjáš, D, Caldwell, A, Cattadori, C, Chernogorov, A, D’Andrea, V, Demidova, EV, Vacri, AD, Domula, A, Doroshkevich, E, Egorov, V, Falkenstein, R, Fedorova, O, Freund, K, Frodyma, N, Gangapshev, A, Garfagnini, A, Grabmayr, P, Gurentsov, V, Gusev, K, Hegai, A, Heisel, M, Hemmer, S, Heusser, G, Hofmann, W, Hult, M, Inzhechik, LV, Janicskó Csáthy, J, Jochum, J, Junker, M, Kazalov, V, Kihm, T, Kirpichnikov, IV, Kirsch, A, Klimenko, A, Knöpfle, KT, Kochetov, O, Kornoukhov, VN, Kuzminov, VV, Laubenstein, M, Lazzaro, A, Lebedev, VI, Lehnert, B, Liao, HY, Lindner, M, Lippi, I, Lubashevskiy, A, Lubsandorzhiev, B, Lutter, G, Macolino, C, Majorovits, B, Maneschg, W, Medinaceli, E, Misiaszek, M, Moseev, P, Nemchenok, I, Palioselitis, D, Panas, K, Pandola, L, Pelczar, K, Pullia, A, Riboldi, S, Rumyantseva, N, Sada, C, Salathe, M, Schmitt, C, Schneider, B, Schönert, S, Schreiner, J, Schütz, AK, Schulz, O, Schwingenheuer, B, Selivanenko, O, Shirchenko, M, Simgen, H, Smolnikov, A, Stanco, L, Stepaniuk, M, Ur, CA, Vanhoefer, L, and Vasenko, AA

Subjects
physics.ins-det, nucl-ex, Nuclear & Particles Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics
Abstract

An optimized digital shaping filter has been developed for the Gerda experiment which searches for neutrinoless double beta decay in $$^{76}$$76Ge. The Gerda Phase I energy calibration data have been reprocessed and an average improvement of 0.3 keV in energy resolution (FWHM) corresponding to 10 % at the $$Q$$Q value for $$0\nu \beta \beta $$0νββ decay in $$^{76}$$76Ge is obtained. This is possible thanks to the enhanced low-frequency noise rejection of this Zero Area Cusp (ZAC) signal shaping filter.

Published
2015

19. Production, characterization and operation of 76Ge enriched BEGe detectors in GERDA

Author

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

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

Published
2015

20. The background in the 0νββ experiment Gerda

Author

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

Subjects
physics.ins-det, hep-ex, Nuclear & Particles Physics, Quantum Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics
Abstract

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

Published
2014

21. Pulse shape discrimination for GERDA Phase I data

Author

Agostini, M, Allardt, M, Andreotti, E, Bakalyarov, AM, Balata, M, Barabanov, I, Heider, MB, Barros, N, Baudis, L, Bauer, C, Becerici-Schmidt, N, Bellotti, E, Belogurov, S, Belyaev, ST, Benato, G, Bettini, A, Bezrukov, L, Bode, T, Brudanin, V, Brugnera, R, Budjáš, D, Caldwell, A, Cattadori, C, Chernogorov, A, Cossavella, F, Demidova, EV, Domula, A, Egorov, V, Falkenstein, R, Ferella, A, Freund, K, Frodyma, N, Gangapshev, A, Garfagnini, A, Gotti, C, Grabmayr, P, Gurentsov, V, Gusev, K, Guthikonda, KK, Hampel, W, Hegai, A, Heisel, M, Hemmer, S, Heusser, G, Hofmann, W, Hult, M, Inzhechik, LV, Ioannucci, L, Csáthy, JJ, Jochum, J, Junker, M, Kihm, T, Kirpichnikov, IV, Kirsch, A, Klimenko, A, Knöpfle, KT, Kochetov, O, Kornoukhov, VN, Kuzminov, VV, Laubenstein, M, Lazzaro, A, Lebedev, VI, Lehnert, B, Liao, HY, Lindner, M, Lippi, I, Liu, X, Lubashevskiy, A, Lubsandorzhiev, B, Lutter, G, Macolino, C, Machado, AA, Majorovits, B, Maneschg, W, Misiaszek, M, Nemchenok, I, Nisi, S, O’Shaughnessy, C, Pandola, L, Pelczar, K, Pessina, G, Pullia, A, Riboldi, S, Rumyantseva, N, Sada, C, Salathe, M, Schmitt, C, Schreiner, J, Schulz, O, Schwingenheuer, B, Schönert, S, Shevchik, E, Shirchenko, M, Simgen, H, Smolnikov, A, Stanco, L, Strecker, H, Tarka, M, Ur, CA, 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 experiment located at the Laboratori Nazionali del Gran Sasso of INFN searches for neutrinoless double beta (0νββ) decay of 76Ge using germanium diodes as source and detector. In Phase I of the experiment eight semi-coaxial and five BEGe type detectors have been deployed. The latter type is used in this field of research for the first time. All detectors are made from material with enriched 76Ge fraction. The experimental sensitivity can be improved by analyzing the pulse shape of the detector signals with the aim to reject background events. This paper documents the algorithms developed before the data of Phase I were unblinded. The double escape peak (DEP) and Compton edge events of 2.615 MeV γ rays from 208Tl decays as well as two-neutrino double beta (2νββ) decays of 76Ge are used as proxies for 0νββ decay. For BEGe detectors the chosen selection is based on a single pulse shape parameter. It accepts 0.92 ± 0.02 of signal-like events while about 80 % of the background events at Qββ = 2039 keV are rejected. For semi-coaxial detectors three analyses are developed. The one based on an artificial neural network is used for the search of 0νββ decay. It retains 90 % of DEP events and rejects about half of the events around Qββ. The 2νββ events have an efficiency of 0.85±0.02 and the one for 0νββ decays is estimated to be 0.90+0.05−0.09. A second analysis uses a likelihood approach trained on Compton edge events. The third approach uses two pulse shape parameters. The latter two methods confirm the classification of the neural network since about 90 % of the data events rejected by the neural network are also removed by both of them. In general, the selection efficiency extracted from DEP events agrees well with those determined from Compton edge events or from 2νββ decays.

Published
2013

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

Author

Ackermann, K-H, Agostini, M, Allardt, M, Altmann, M, Andreotti, E, Bakalyarov, AM, Balata, M, Barabanov, I, Barnabé Heider, M, Barros, N, Baudis, L, Bauer, C, Becerici-Schmidt, N, Bellotti, E, Belogurov, S, Belyaev, ST, Benato, G, Bettini, A, Bezrukov, L, Bode, T, Brudanin, V, Brugnera, R, Budjáš, D, Caldwell, A, Cattadori, C, Chernogorov, A, Chkvorets, O, Cossavella, F, D‘Andragora, A, Demidova, EV, Denisov, A, di Vacri, A, Domula, A, Egorov, V, Falkenstein, R, Ferella, A, Freund, K, Froborg, F, Frodyma, N, Gangapshev, A, Garfagnini, A, Gasparro, J, Gazzana, S, Gonzalez de Orduna, R, Grabmayr, P, Gurentsov, V, Gusev, K, Guthikonda, KK, Hampel, W, Hegai, A, Heisel, M, Hemmer, S, Heusser, G, Hofmann, W, Hult, M, Inzhechik, LV, Ioannucci, L, Janicskó Csáthy, J, Jochum, J, Junker, M, Kankanyan, R, Kianovsky, S, Kihm, T, Kiko, J, Kirpichnikov, IV, Kirsch, A, Klimenko, A, Knapp, M, Knöpfle, KT, Kochetov, O, Kornoukhov, VN, Kröninger, K, Kusminov, V, Laubenstein, M, Lazzaro, A, Lebedev, VI, Lehnert, B, Lenz, D, Liao, H, Lindner, M, Lippi, I, Liu, J, Liu, X, Lubashevskiy, A, Lubsandorzhiev, B, Machado, AA, Majorovits, B, Maneschg, W, Marissens, G, Mayer, S, Meierhofer, G, Nemchenok, I, Niedermeier, L, Nisi, S, Oehm, J, O’Shaughnessy, C, Pandola, L, Peiffer, P, Pelczar, K, and Pullia, A

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, physics.ins-det, hep-ex, 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 search for neutrinoless double beta decay of 76Ge with the eponymous detector. The experiment has been installed and commissioned at the Laboratori Nazionali del Gran Sasso and has started operation in November 2011. The design, construction and first operational results are described, along with detailed information from the R&D phase. © 2013 The Author(s).

Published
2013

23. Characterization of 30 76 Ge enriched Broad Energy Ge detectors for GERDA Phase II.

Author

Agostini, M, 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, Vasenko, AA, Agostini, M, 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

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

24. Background-free search for neutrinoless double-β decay of 76 Ge with GERDA

Author

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, 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, Hakenmöller, 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, Kneibl, 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, and Schreiner, J

Abstract

©2017 Macmillan Publishers Limited, part of Springer Nature. All rights reserved. Many extensions of the Standard Model of particle physics explain the dominance of matter over antimatter in our Universe by neutrinos being their own antiparticles. This would imply the existence of neutrinoless double-β decay, which is an extremely rare lepton-number-violating radioactive decay process whose detection requires the utmost background suppression. Among the programmes that aim to detect this decay, the GERDA Collaboration is searching for neutrinoless double-β decay of 76 Ge by operating bare detectors, made of germanium with an enriched 76 Ge fraction, in liquid argon. After having completed Phase I of data taking, we have recently launched Phase II. Here we report that in GERDA Phase II we have achieved a background level of approximately 10 â '3 counts keV â '1 kg â '1 yr â '1. This implies that the experiment is background-free, even when increasing the exposure up to design level. This is achieved by use of an active veto system, superior germanium detector energy resolution and improved background recognition of our new detectors. No signal of neutrinoless double-β decay was found when Phase I and Phase II data were combined, and we deduce a lower-limit half-life of 5.3 × 10 25 years at the 90 per cent confidence level. Our half-life sensitivity of 4.0 × 10 25 years is competitive with the best experiments that use a substantially larger isotope mass. The potential of an essentially background-free search for neutrinoless double-β decay will facilitate a larger germanium experiment with sensitivity levels that will bring us closer to clarifying whether neutrinos are their own antiparticles.

Published
2017

25. Limit on the radiative neutrinoless double electron capture of36Ar 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, and Pullia, A

Abstract

© 2016, The Author(s). 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 of36Ar 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 of36Ar was established: T1 / 2> 3.6 × 1021years at 90% CI.

Published
2016

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

Author

collaboration, G, Agostini, M, Balata, M, D'Andrea, V, di Vacri, A, Ioannucci, L, Junker, M, Laubenstein, M, Macolino, C, Pandola, L, Borowicz, D, Frodyma, N, Misiaszek, M, Panas, K, Pelczar, K, Wojcik, M, Zuzel, G, Allardt, M, Barros, N, Domula, A, Lehnert, B, Schneider, B, Wester, T, Wilsenach, H, Zuber, K, Brudanin, V, Egorov, V, Gusev, K, Klimenko, A, Kochetov, O, Lubashevskiy, A, Nemchenok, I, Rumyantseva, N, Shevchik, E, Shirchenko, M, Zhitnikov, I, Zinatulina, D, Hult, M, Lutter, G, Bauer, C, Gangapshev, A, Heisel, M, Hofmann, W, Kihm, T, Kirsch, A, Knöpfle, KT, Lindner, M, Maneschg, W, Salathe, M, Schreiner, J, Schwingenheuer, B, Simgen, H, Smolnikov, A, Stepaniuk, M, Strecker, H, Wagner, V, Wegmann, A, Bellotti, E, Cattadori, C, Pullia, A, Riboldi, S, Barabanov, I, Belogurov, S, Bezrukov, L, Doroshkevich, E, Fedorova, O, Gurentsov, V, Inzhechik, LV, Kazalov, V, Kornoukhov, VN, Kuzminov, VV, Lubsandorzhiev, B, Moseev, P, Selivanenko, O, Veresnikova, A, Yanovich, E, Chernogorov, A, Demidova, EV, Kirpichnikov, IV, Vasenko, AA, Bakalyarov, AM, Belyaev, ST, Lebedev, VI, Zhukov, SV, Becerici-Schmidt, N, Caldwell, A, Liao, HY, Majorovits, B, Palioselitis, D, and Schulz, O

Abstract

© 2016 Elsevier B.V. The GERDA experiment at LNGS of INFN is equipped with an active muon veto. The main part of the system is a water Cherenkov veto with 66 PMTs in the water tank surrounding the GERDA cryostat. The muon flux recorded by this veto shows a seasonal modulation. Two causes have been identified: (i) secondary muons from the CNGS neutrino beam (2.2%) and (ii) a temperature modulation of the atmosphere (1.4%). A mean cosmic muon rate of Iμ0=(3.477±0.002stat±0.067sys)×10−4/(s · m2) was found in good agreement with other experiments at LNGS. Combining the present result with those from previous experiments at LNGS the effective temperature coefficient αT,Lngsis determined to 0.93 ± 0.03. A fit of the temperature coefficients measured at various underground sites yields a kaon to pion ratio rK/πof 0.10 ± 0.03.

Published
2016

27. Results on ββ decay with emission of two neutrinos or Majorons in 76Ge from GERDA Phase I

Author

GERDA Collaboration, Agostini, M, Allardt, M, Bakalyarov, AM, Balata, M, Barabanov, I, Barros, N, Baudis, L, Bauer, C, Becerici-Schmidt, N, Bellotti, E, Belogurov, S, Belyaev, ST, Benato, G, Bettini, A, Bezrukov, L, Bode, T, Borowicz, D, Brudanin, V, Brugnera, R, Budjáš, D, Caldwell, A, Cattadori, C, Chernogorov, A, D’Andrea, V, Demidova, EV, di Vacri, A, Domula, A, Doroshkevich, E, Egorov, V, Falkenstein, R, Fedorova, O, Freund, K, Frodyma, N, Gangapshev, A, Garfagnini, A, Grabmayr, P, Gurentsov, V, Gusev, K, Hegai, A, Heisel, M, Hemmer, S, Heusser, G, Hofmann, W, Hult, M, Inzhechik, LV, Csáthy, J Janicskó, Jochum, J, Junker, M, Kazalov, V, Kihm, T, Kirpichnikov, IV, Kirsch, A, Klimenko, A, Knöpfle, KT, Kochetov, O, Kornoukhov, VN, Kuzminov, VV, Laubenstein, M, Lazzaro, A, Lebedev, VI, Lehnert, B, Liao, HY, Lindner, M, Lippi, I, Lubashevskiy, A, Lubsandorzhiev, B, Lutter, G, Macolino, C, Majorovits, B, Maneschg, W, Medinaceli, E, Misiaszek, M, Moseev, P, Nemchenok, I, Palioselitis, D, Panas, K, Pandola, L, Pelczar, K, Pullia, A, Riboldi, S, Rumyantseva, N, Sada, C, Salathe, M, Schmitt, C, Schneider, B, Schönert, S, Schreiner, J, Schütz, A-K, Schulz, O, Schwingenheuer, B, Selivanenko, O, Shirchenko, M, Simgen, H, Smolnikov, A, Stanco, L, Stepaniuk, M, Ur, CA, Vanhoefer, L, and Vasenko, AA

Subjects
Quantum Physics, Particle and Plasma Physics, Molecular, Nuclear, nucl-ex, physics.ins-det, Atomic, Nuclear & Particles Physics
Abstract

A search for neutrinoless ββ decay processes accompanied with Majoron emission has been performed using data collected during PhaseI of the GERmanium Detector Array (GERDA) experiment at the Laboratori Nazionali del Gran Sasso of INFN (Italy). Processes with spectral indices n = 1, 2, 3, 7 were searched for. No signals were found and lower limits of the order of 1023yr on their half-lives were derived, yielding substantially improved results compared to previous experiments with 76Ge. A new result for the half-life of the neutrino-accompanied ββ decay of 76Ge with significantly reduced uncertainties is also given, resulting in (Formula presented.) yr.

Published
2015

28. Production, characterization and operation of76Ge enriched BEGe detectors in GERDA: GERDA Collaboration

Author

Agostini, M, Allardt, M, Andreotti, E, Bakalyarov, AM, Balata, M, Barabanov, I, Barros, N, Baudis, L, Bauer, C, Becerici-Schmidt, N, Bellotti, E, Belogurov, S, Belyaev, ST, Benato, G, Bettini, A, Bezrukov, L, Bode, T, Borowicz, D, Brudanin, V, Brugnera, R, Budjáš, D, Caldwell, A, Cattadori, C, Chernogorov, A, D’Andrea, V, Demidova, EV, Domula, A, Egorov, V, Falkenstein, R, Freund, K, Frodyma, N, Gangapshev, A, Garfagnini, A, Gotti, C, Grabmayr, P, Gurentsov, V, Gusev, K, Hegai, A, Heisel, M, Hemmer, S, Heusser, G, Hofmann, W, Hult, M, Inzhechik, LV, Ioannucci, L, Janicskó Csáthy, J, Jochum, J, Junker, M, Kazalov, V, Kihm, T, Kirpichnikov, IV, Kirsch, A, Klimenko, A, Knöpfle, KT, Kochetov, O, Kornoukhov, VN, Kuzminov, VV, Laubenstein, M, Lazzaro, A, Lebedev, VI, Lehnert, B, Liao, HY, Lindner, M, Lippi, I, Lubashevskiy, A, Lubsandorzhiev, B, Lutter, G, Macolino, C, Majorovits, B, Maneschg, W, Misiaszek, M, Nemchenok, I, Nisi, S, O’Shaughnessy, C, Palioselitis, D, Pandola, L, Pelczar, K, Pessina, G, Pullia, A, Riboldi, S, and Rumyantseva, N

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

© 2015, The Author(s). The GERmanium Detector Array (Gerda) at the Gran Sasso Underground Laboratory (LNGS) searches for the neutrinoless double beta decay (0νββ) of76Ge. Germanium detectors made of material with an enriched76Ge fraction act simultaneously as sources and detectors for this decay. During Phase I of theexperiment mainly refurbished semi-coaxial Ge detectors from former experiments were used. For the upcoming Phase II, 30 new76Ge enriched detectors of broad energy germanium (BEGe)-type were produced. A subgroup of these detectors has already been deployed in Gerda during Phase I. The present paper reviews the complete production chain of these BEGe detectors including isotopic enrichment, purification, crystal growth and diode production. The efforts in optimizing the mass yield and in minimizing the exposure of the76Ge enriched germanium to cosmic radiation during processing are described. Furthermore, characterization measurements in vacuum cryostats of the first subgroup of seven BEGe detectors and their long-term behavior in liquid argon are discussed. The detector performance fulfills the requirements needed for the physics goals of Gerda Phase II.

Published
2015

29. Production, characterization and operation of 76Ge enriched BEGe detectors in GERDA: GERDA Collaboration

Author

Agostini, M, Allardt, M, Andreotti, E, Bakalyarov, AM, Balata, M, Barabanov, I, Barros, N, Baudis, L, Bauer, C, Becerici-Schmidt, N, Bellotti, E, Belogurov, S, Belyaev, ST, Benato, G, Bettini, A, Bezrukov, L, Bode, T, Borowicz, D, Brudanin, V, Brugnera, R, Budjáš, D, Caldwell, A, Cattadori, C, Chernogorov, A, D’Andrea, V, Demidova, EV, Domula, A, Egorov, V, Falkenstein, R, Freund, K, Frodyma, N, Gangapshev, A, Garfagnini, A, Gotti, C, Grabmayr, P, Gurentsov, V, Gusev, K, Hegai, A, Heisel, M, Hemmer, S, Heusser, G, Hofmann, W, Hult, M, Inzhechik, LV, Ioannucci, L, Janicskó Csáthy, J, Jochum, J, Junker, M, Kazalov, V, Kihm, T, Kirpichnikov, IV, Kirsch, A, Klimenko, A, Knöpfle, KT, Kochetov, O, Kornoukhov, VN, Kuzminov, VV, Laubenstein, M, Lazzaro, A, Lebedev, VI, Lehnert, B, Liao, HY, Lindner, M, Lippi, I, Lubashevskiy, A, Lubsandorzhiev, B, Lutter, G, Macolino, C, Majorovits, B, Maneschg, W, Misiaszek, M, Nemchenok, I, Nisi, S, O’Shaughnessy, C, Palioselitis, D, Pandola, L, Pelczar, K, Pessina, G, Pullia, A, Riboldi, S, Rumyantseva, N, Sada, C, Salathe, M, Schmitt, C, Schreiner, J, Schulz, O, Schütz, AK, Schwingenheuer, B, Schönert, S, Shevchik, E, Shirchenko, M, Simgen, H, Smolnikov, A, Stanco, L, Strecker, H, Ur, CA, Vanhoefer, L, Vasenko, AA, von Sturm, K, and Wagner, V

Subjects
Quantum Physics, Particle and Plasma Physics, Physics::Instrumentation and Detectors, hep-ex, Molecular, High Energy Physics::Experiment, Nuclear, Nuclear Experiment, nucl-ex, physics.ins-det, Nuclear & Particles Physics, Atomic
Abstract

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

Published
2015

30. The Gerda experiment for the search of 0νββ decay in76Ge

Author

Ackermann, KH, Agostini, M, Allardt, M, Altmann, M, Andreotti, E, Bakalyarov, AM, Balata, M, Barabanov, I, Barnabé Heider, M, Barros, N, Baudis, L, Bauer, C, Becerici-Schmidt, N, Bellotti, E, Belogurov, S, Belyaev, ST, Benato, G, Bettini, A, Bezrukov, L, Bode, T, Brudanin, V, Brugnera, R, Budjáš, D, Caldwell, A, Cattadori, C, Chernogorov, A, Chkvorets, O, Cossavella, F, D'Andragora, A, Demidova, EV, Denisov, A, di Vacri, A, Domula, A, Egorov, V, Falkenstein, R, Ferella, A, Freund, K, Froborg, F, Frodyma, N, Gangapshev, A, Garfagnini, A, Gasparro, J, Gazzana, S, Gonzalez de Orduna, R, Grabmayr, P, Gurentsov, V, Gusev, K, Guthikonda, KK, Hampel, W, Hegai, A, Heisel, M, Hemmer, S, Heusser, G, Hofmann, W, Hult, M, Inzhechik, LV, Ioannucci, L, Janicskó Csáthy, J, Jochum, J, Junker, M, Kankanyan, R, Kianovsky, S, Kihm, T, Kiko, J, Kirpichnikov, IV, Kirsch, A, Klimenko, A, Knapp, M, Knöpfle, KT, Kochetov, O, Kornoukhov, VN, Kröninger, K, Kusminov, V, Laubenstein, M, Lazzaro, A, Lebedev, VI, and Lehnert, B

Abstract

The Gerda collaboration is performing a search for neutrinoless double beta decay of76Ge with the eponymous detector. The experiment has been installed and commissioned at the Laboratori Nazionali del Gran Sasso and has started operation in November 2011. The design, construction and first operational results are described, along with detailed information from the R&D phase. © 2013 The Author(s).

Published
2013

31. Pulse shape discrimination in the IGEX experiment

Author

Cebrian, S., Garcia, E., Gonzalez, D., Irastorza, Ig, Morales, A., Morales, J., Solorzano, Ao, Puimedon, J., Sarsa, Ml, Villar, Ja, Aalseth, Ce, Avignone, Ft, Brodzinski, Rl, Hensley, Wk, Miley, Hs, Reeves, Jh, Kirpichnikov, Iv, Klimenko, Aa, Osetrov, Sb, Smolnikov, Aa, Vasenko, Aa, Vasiliev, Si, Pogosov, Vs, Tamanyan, Ag, Igex, Collaboration, Bellotti, E., Declais, Y., Strolin, P., and Zanotti, L.

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

Author

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

Abstract

A search for full energy depositions from bosonic keV-scale dark matter candidates of masses between 65 and 1021 keV has been performed with data collected during Phase II of the GERmanium Detector Array (Gerda) experiment. Our analysis includes direct dark matter absorption as well as dark Compton scattering. With a total exposure of 105.5 kg years, no evidence for a signal above the background has been observed. The resulting exclusion limits deduced with either Bayesian or Frequentist statistics are the most stringent direct constraints in the major part of the 140-1021 keV mass range. As an example, at a mass of 150 keV the dimensionless coupling of dark photons and axion-like particles to electrons has been constrained to α ' / α < 8.7 × 10 - 24 and g ae < 3.3 × 10 - 12 at 90% credible interval (CI), respectively. Additionally, a search for peak-like signals from beyond the Standard Model decays of nucleons and electrons is performed. We find for the inclusive decay of a single neutron in 76 Ge a lower lifetime limit of τ n > 1.5 × 10 24 years and for a proton τ p > 1.3 × 10 24 years at 90% CI. For the electron decay e - → ν e γ a lower limit of τ e > 5.4 × 10 25 years at 90% CI has been determined., Supplementary Information: The online version contains supplementary material available at 10.1140/epjc/s10052-024-13020-0., (© The Author(s) 2024.)

Published
2024
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33. Final Results of GERDA on the Two-Neutrino Double-β Decay Half-Life of ^{76}Ge.

Author

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

Abstract

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

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

Author

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

Abstract

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

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

Author

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

Abstract

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

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

Author

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

Abstract

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

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

Author

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

Abstract

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

Published
2022
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38. Calibration of the Gerda experiment.

Author

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

Abstract

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

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

Author

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

Abstract

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

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

Author

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

Abstract

The GERmanium Detector Array (GERDA) experiment searched for the lepton-number-violating neutrinoless double-β (0νββ) decay of ^{76}Ge, whose discovery would have far-reaching implications in cosmology and particle physics. By operating bare germanium diodes, enriched in ^{76}Ge, in an active liquid argon shield, GERDA achieved an unprecedently low background index of 5.2×10^{-4} counts/(keV kg yr) in the signal region and met the design goal to collect an exposure of 100 kg yr in a background-free regime. When combined with the result of Phase I, no signal is observed after 127.2 kg yr of total exposure. A limit on the half-life of 0νββ decay in ^{76}Ge is set at T&#95;{1/2}>1.8×10^{26}  yr at 90% C.L., which coincides with the sensitivity assuming no signal.

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

Author

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

Abstract

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

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

Author

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

Abstract

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

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

Author

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

Abstract

The GERmanium Detector Array (Gerda) is a low background experiment located at the Laboratori Nazionali del Gran Sasso in Italy, which searches for neutrinoless double-beta decay of 76 Ge into 76 Se+2e - . Gerda has been conceived in two phases. Phase II, which started in December 2015, features several novelties including 30 new 76 Ge enriched detectors. These were manufactured according to the Broad Energy Germanium (BEGe) detector design that has a better background discrimination capability and energy resolution compared to formerly widely-used types. Prior to their installation, the new BEGe detectors were mounted in vacuum cryostats and characterized in detail in the Hades underground laboratory in Belgium. This paper describes the properties and the overall performance of these detectors during operation in vacuum. The characterization campaign provided not only direct input for Gerda Phase II data collection and analyses, but also allowed to study detector phenomena, detector correlations as well as to test the accuracy of pulse shape simulation codes., (© The Author(s) 2019.)

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

Author

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

Abstract

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

Published
2018
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45. Results on neutrinoless double-β decay of 76Ge from phase I of the GERDA experiment.

Author

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

Abstract

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

Published
2013
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