Münster 2017 – wissenschaftliches Programm
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T: Fachverband Teilchenphysik
T 56: Neutrinophysik 4 (Doppelbetazerfall und Massen)
T 56.2: Vortrag
Dienstag, 28. März 2017, 17:05–17:20, VSH 118
Discrimination of single-site and multi-site events in CZT-CPG detectors for the COBRA experiment — •Stefan Zatschler for the COBRA collaboration — TU Dresden, Institut für Kern- und Teilchenphysik, Germany
The COBRA experiment is aiming to search for the rare neutrinoless double beta-decay (0νββ-decay) with CdZnTe detectors. Currently, a demonstrator setup is operated at the underground facility LNGS in Italy. Each monolithic detector of the 4×4×4 array is 1 cm3 in size and equipped with a coplanar grid (CPG) readout. This demonstrator is used to characterize potential background components and to prove that stable operation over several years can be achieved. One key requirement for a high sensitivity is the ability to differentiate between signal and background events. In this context, pulse-shape analysis has been found to show excellent capabilities while maintaining a high signal efficiency. The 0νββ-decay signal is expected to be almost always a single-site event (SSE) within only one detector. Hence, all multi-detector and multi-site events (MSEs), which are likely induced by multiply scattered photons in the same crystal, can be vetoed as background. The imprints on the recorded pulse-shapes caused by the drift of multiple, separated charge clouds can be used to discriminate those MSEs from signal-like SSEs. In this talk, an overview of the developed technique to discriminate between both event types will be presented. Additionally, the results of a dedicated laboratory experiment, which makes use of coincident Compton scattering to create a library of SSEs, as well as an efficiency estimate will be shown.