The Cadmium-Zinc-Telluride 0-Neutrino-Double-Beta Research Apparatus
(COBRA-Experiment) investigates the theoretically predicted neutrinoless
double beta decay (0νββ-decay) to indirectly determine the effective Ma-
jorana mass of the electron-neutrino by a measurement of the half-life of
the 0νββ-decay using room-temperature semiconducting Cadmium-Zinc-
Telluride-detectors (CZT). The detectors are made of elements containing
several isotopes that decay via double beta decay (ββ-decay). In such a con-
figuration the detector itself becomes the source of the decay and, hence,
the efficiency for the detection of such events rises.
This work covers the investigations and characterizations made on the CZT
detectors used in the COBRA-Experiment, currently running. Prior to in-
stallation the physical properties of the detectors are analyzed and during
operation the stability of the detectors is monitored. For the laboratory
analysis three dedicated setups are developed that allow for detailed inves-
tigations of different properties of the detectors. Beside the working point
determination and the analysis of the temperature dependence of the de-
tector performance, the spatial detector response to localized irradiation is
analyzed and a setup to generate a library of specific pulse shapes is designed
and operated. Furthermore, an investigation for a possible discrimination
of α- and β-decay events based on pulse shape discrimination is performed
as well as an analysis of the long term stability of underground operated
CZT detectors.