Background rejection of n+ surface events in GERDA Phase II

The GERDA experiment searches for neutrinoless double beta (0vββ) decay in 76Ge using an array of high purity germanium (HPGe) detectors immersed in liquid argon (LAr). Phase II of the experiment uses 30 new broad energy germanium (BEGe) detectors with superior pulse shape discrimination capabilitie...

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Bibliographic Details
Published inJournal of physics. Conference series Vol. 718; no. 6; pp. 62035 - 62040
Main Author Lehnert, Björn
Format Journal Article
LanguageEnglish
Published Bristol IOP Publishing 01.05.2016
Subjects
Argon
Beta decay
Detectors
Discrimination
Germanium
Particle decay
Physics
Pulse shape
Sensors
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Summary:The GERDA experiment searches for neutrinoless double beta (0vββ) decay in 76Ge using an array of high purity germanium (HPGe) detectors immersed in liquid argon (LAr). Phase II of the experiment uses 30 new broad energy germanium (BEGe) detectors with superior pulse shape discrimination capabilities compared to the previously used semi-coaxial detector design. By far the largest background component for BEGe detectors in GERDA are n+-surface events from 42K β decays which are intrinsic in LAr. The β particles with up to 3.5 MeV can traverse the 0.5 to 0.9 mm thick electrode and deposit energy within the region of interest for the 0vββ decay. However, those events have particular pulse shape features allowing for a strong discrimination. The understanding and simulation of this background, showing a reduction by up to a factor 145 with pulse shape discrimination alone, is presented in this work.
ISSN:1742-6588
1742-6596
DOI:10.1088/1742-6596/718/6/062035