https://doi.org/10.1140/epjc/s10052-015-3627-y
Regular Article - Experimental Physics
Results on
decay with emission of two neutrinos or Majorons in
Ge from GERDA Phase I
GERDA Collaboration
1
LNGS, Assergi, Italy
2
INFN Laboratori Nazionali del Gran Sasso and Gran Sasso Science Institute, Assergi, 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
Institute for Reference Materials and Measurements, Geel, Belgium
8
Max-Planck-Institut für Kernphysik, Heidelberg, Germany
9
Dipartimento di Fisica, Università Milano Bicocca, Milan, Italy
10
INFN Milano Bicocca, Milan, Italy
11
Dipartimento di Fisica, Università degli Studi di Milano e INFN Milano, Milan, Italy
12
Institute for Nuclear Research of the Russian Academy of Sciences, Moscow, Russia
13
Institute for Theoretical and Experimental Physics, Moscow, Russia
14
National Research Centre “Kurchatov Institute”, Moscow, Russia
15
Max-Planck-Institut für Physik, Munich, Germany
16
Physik Department and Excellence Cluster Universe, Technische Universität München, Munich, Germany
17
Dipartimento di Fisica e Astronomia dell‘Università di Padova, Padua, Italy
18
INFN Padova, Padua, Italy
19
Physikalisches Institut, Eberhard Karls Universität Tübingen, Tübingen, Germany
20
Physik Institut der Universität Zürich, Zurich, Switzerland
21
Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA, USA
22
Moscow Institute of Physics and Technology, Moscow, Russia
23
International University for Nature, Society and Man “Dubna”, Dubna, Russia
* e-mail: gerda-eb@mpi-hd.mpg.de
** e-mail: grabmayr@uni-tuebingen.de
Received:
9
January
2015
Accepted:
18
August
2015
Published online:
9
September
2015
A search for neutrinoless 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
were searched for. No signals were found and lower limits of the order of 10
yr on their half-lives were derived, yielding substantially improved results compared to previous experiments with
Ge. A new result for the half-life of the neutrino-accompanied
decay of
Ge with significantly reduced uncertainties is also given, resulting in
yr.
© SIF and Springer-Verlag Berlin Heidelberg, 2015