Wuppertal 2015 – scientific programme

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T: Fachverband Teilchenphysik

T 10: Niederenergie Neutrinophysik I

T 10.2: Talk

Monday, March 9, 2015, 14:20–14:35, I.12.01 (HS 30)

Detecting surface events at the COBRA Experiment — •Jan Tebrügge for the COBRA collaboration — Exp. Physik IV, TU Dortmund

The aim of the COBRA experiment is to prove the existence of neutrinoless double-beta-decay and to measure its half-life. For this purpose the COBRA demonstrator, a prototype for a large-scale experiment, is operated at the Gran Sasso Underground Laboratory (LNGS) in Italy. The demonstrator is a detector array made of 64 Cadmium-Zinc-Telluride (CdZnTe) semiconductor detectors in the coplanar grid anode configuration. Each detector is 1 * 1 * 1 ccm in size. This setup is used to investigate the experimental issues of operating CdZnTe detectors in low background mode and identify potential background components. As the "detector = source" principle is used, the neutrinoless double beta decay COBRA searches for happens within the whole detector volume. Consequently, events on the surface of the detectors are considered as background. These surface events are a main background component, stemming mainly from the natural radioactivity, especially radon. This talk explains to what extent surface events occur and shows how these are recognized and vetoed in the analysis using pulse shape discrimination algorithms.