https://doi.org/10.1140/epjc/s10052-017-5499-9
Regular Article - Experimental Physics
Mitigation of 
Ar/K background for the GERDA Phase II experiment
1
Max Planck Institut für Kernphysik, Heidelberg, Germany
2
Joint Institute for Nuclear Research, Dubna, Russia
3
Gran Sasso Science Institute, L’Aquila, Italy
4
Physik Department E15, Technische Universität München, Munich, Germany
5
Institute for Nuclear Research of the Russian Academy of Sciences, Moscow, Russia
6
Russian Research Center Kurchatov Institute, Moscow, Russia
7
Institut für Kern- und Teilchenphysik Technische Universität Dresden, Dresden, Germany
8
Institute of Physics, Jagellonian University, Cracow, Poland
9
Physik Institut der Universität Zürich, Zurich, Switzerland
10
Physics Department, Carleton University, Ottawa, Canada
11
INFN Laboratori Nazionali del Gran Sasso, LNGS, Assergi, Italy
* e-mail: lav@nusun.jinr.ru
Received:
2
August
2017
Accepted:
21
December
2017
Published online:
11
January
2018
Background coming from the Ar decay chain is considered to be one of the most relevant for the Gerda experiment, which searches for the neutrinoless double beta decay of 
Ge. The sensitivity strongly relies on the absence of background around the Q-value of the decay. Background coming from K, a progeny of Ar, can contribute to that background via electrons from the continuous spectrum with an endpoint at 3.5 MeV. Research and development on the suppression methods targeting this source of background were performed at the low-background test facility LArGe . It was demonstrated that by reducing K ion collection on the surfaces of the broad energy germanium detectors in combination with pulse shape discrimination techniques and an argon scintillation veto, it is possible to suppress K background by three orders of magnitude. This is sufficient for Phase II of the Gerda experiment.
© The Author(s), 2018
