https://doi.org/10.1140/epjc/s10052-021-09184-8
Special Article – Tools for Experiment and Theory
Characterization of inverted coaxial 
Ge detectors in GERDA for future double-
decay experiments
1
INFN Laboratori Nazionali del Gran Sasso and Gran Sasso Science Institute, Assergi, Italy
2
INFN Laboratori Nazionali del Gran Sasso and Università degli Studi dell’Aquila, L’Aquila, Italy
3
INFN Laboratori Nazionali del Sud, Catania, Italy
4
Institute of Physics, Jagiellonian University, Cracow, Poland
5
Institut für Kern- und Teilchenphysik, Technische Universität Dresden, Dresden, Germany
6
Joint Institute for Nuclear Research, Dubna, Russia
7
European Commission, JRC-Geel, Geel, Belgium
8
Max-Planck-Institut für Kernphysik, Heidelberg, Germany
9
Department of Physics and Astronomy, University College London, London, UK
10
Dipartimento di Fisica, Università Milano Bicocca, Milan, Italy
11
INFN Milano Bicocca, Milan, Italy
12
Dipartimento di Fisica, Università degli Studi di Milano and INFN Milano, Milan, Italy
13
Institute for Nuclear Research of the Russian Academy of Sciences, Moscow, Russia
14
Institute for Theoretical and Experimental Physics, NRC “Kurchatov Institute”, Moscow, Russia
15
National Research Centre “Kurchatov Institute”, Moscow, Russia
16
Max-Planck-Institut für Physik, Munich, Germany
17
Physik Department, Technische Universität München, Munich, Germany
18
Dipartimento di Fisica e Astronomia, Università degli Studi di Padova, Padua, Italy
19
INFN Padova, Padua, Italy
20
Physikalisches Institut, Eberhard Karls Universität Tübingen, Tübingen, Germany
21
Physik-Institut, Universität Zürich, Zurich, Switzerland
22
NRNU MEPhI, Moscow, Russia
23
Moscow Institute of Physics and Technology, Moscow, Russia
24
Leibniz-Institut für Kristallzüchtung, Berlin, Germany
25
Dubna State University, Dubna, Russia
Received:
3
February
2021
Accepted:
27
April
2021
Published online:
7
June
2021
Neutrinoless double- decay of 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 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- decay of Ge (
= 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 
around . This work confirms the feasibility of IC detectors for the next-generation experiment Legend.
© The Author(s) 2021
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Funded by SCOAP3
