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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. 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

15. 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

16. 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

17. 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

18. 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

19. 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

20. 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

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