Background reduction in neutrinoless double beta decay experiments using segmented detectors—A Monte Carlo study for the GERDA setup

The identification of gamma radiation is essential for a new generation of double beta decay experiments. The GERmanium Detector Array, GERDA, located at the INFN Gran Sasso National Laboratory (LNGS) in Italy, uses germanium, enriched in Ge76, as source and detector, and aims at a background level of less than 10-3counts/(kgkeVy) in the region of the QββQββ-value. For the first time highly segmented detectors will be installed in a double beta decay experiment. A detailed GEANT4 Monte Carlo study was performed to evaluate the background reduction achievable by anti-coincidence cuts between crystals and segments.Within the overall geometry of GERDA, the segmentation scheme considered here provides around an order of magnitude of extra background reduction.