Background Rejection of n${}^{+}$ Surface Events in GERDA Phase II

Abstract

The GERDA experiment searches for neutrinoless double beta ($0\nu \beta \beta$) decay in ${}^{76}$Ge 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 ${}^{42}$K $\beta$ decays which are intrinsic in LAr. The $\beta$ 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 $0\nu \beta \beta$ 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.

arXiv commentProceeding TAUP 2015

References in corpus (8)

• Results on neutrinoless double beta decay of 76Ge from GERDA Phase I
• The GERDA experiment for the search of 0νββ decay in ^{76}Ge
• \textsc{MaGe} - a {\sc Geant4}-based Monte Carlo Application Framework for Low-background Germanium Experiments
• Pulse shape discrimination studies with a Broad-Energy Germanium detector for signal identification and background suppression in the GERDA double beta decay experiment
• Results on $\beta \beta$ decay with emission of two neutrinos or Majorons in ${}^{76}$Ge from GERDA Phase I
• Pulse shape discrimination for GERDA Phase I data
• The background in the neutrinoless double beta decay experiment GERDA
• Production, characterization and operation of ${}^{76}$Ge enriched BEGe detectors in GERDA

Cited by in corpus (2)

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