Off-line data processing and analysis for the GERDA experiment

Abstract

GERDA is an experiment designed to look for the neutrinoless double beta decay of Ge-76. The experiment uses an array of high-purity germanium detectors, enriched in Ge-76, directly immersed in liquid argon. GERDA is presently operating eight enriched coaxial detectors (approximately 15 kg of Ge-76) and about 30 new custom-made enriched BEGe detectors will be deployed in the next phase (additional 20 kg of Ge-76). The paper describes the GERDA off-line analysis of the high-purity germanium detector data. Firstly we present the signal processing flow, focusing on the digital filters and on the algorithms used. Secondly we discuss the rejection of non-physical events and the data quality monitoring. The analysis is performed completely with the GERDA software framework (GELATIO), designed to support a multi-channel processing and to perform a modular analysis of digital signals.