Limits on uranium and thorium bulk content in GERDA Phase I detectors

Abstract

Internal contaminations of ${}^{238}$U, ${}^{235}$U and ${}^{232}$Th in the bulk of high purity germanium detectors are potential backgrounds for experiments searching for neutrinoless double beta decay of ${}^{76}$Ge. The data from GERDA Phase~I have been analyzed for alpha events from the decay chain of these contaminations by looking for full decay chains and for time correlations between successive decays in the same detector. No candidate events for a full chain have been found. Upper limits on the activities in the range of a few nBq/kg for ${}^{226}$Ra, ${}^{227}$Ac and ${}^{228}$Th, the long-lived daughter nuclides of ${}^{238}$U, ${}^{235}$U and ${}^{232}$Th, respectively, have been derived. With these upper limits a background index in the energy region of interest from ${}^{226}$Ra and ${}^{228}$Th contamination is estimated which satisfies the prerequisites of a future ton scale germanium double beta decay experiment.

arXiv comment2 figures, 7 pages

References in corpus (6)

• Latest Results from the Heidelberg-Moscow Double Beta Decay Experiment
• Results on neutrinoless double beta decay of 76Ge from GERDA Phase I
• The Igex 76ge Neutrinoless Double-Beta Decay Experiment: Prospects for Next Generation Experiments
• 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
• The background in the neutrinoless double beta decay experiment GERDA

Cited by in corpus (4)

• The Large Enriched Germanium Experiment for Neutrinoless Double Beta Decay (LEGEND)
• Pulse shape analysis in GERDA Phase II
• Main features of detectors and isotopes to investigate double beta decay with increased sensitivity
• An assay-based background projection for the MAJORANA DEMONSTRATOR using Monte Carlo Uncertainty Propagation