Hamburg 2016 – scientific programme
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T: Fachverband Teilchenphysik
T 99: Detektorsysteme IV
T 99.8: Talk
Thursday, March 3, 2016, 18:30–18:45, VMP8 SR 205
Discrimination of Alpha Particles in CdZnTe Detectors with Coplanar Grid for the COBRA Experiment — •Henning Rebber for the COBRA collaboration — Universität Hamburg, Institut für Experimentalphysik, Luruper Chaussee 149, 22761 Hamburg
The aim of the COBRA experiment is the search for neutrinoless double beta decay using CdZnTe semiconductor detectors. A background rate in the order of 10−3 counts per keV, kg and year is intended in order to be sensitive to a half-life larger than 1026 years. Measurements from a demonstrator setup and Monte Carlo simulations indicate that a large background component is due to alpha particles. These generate charge clouds of only few µm in diameter in the detector, leading to characteristic pulse features.
Parameter-based cut criteria were developed to discriminate alpha events by means of their pulse shapes. The cuts were tested on data from alpha and beta irradiation of a (1× 1× 1 ) cm3 CdZnTe detector with coplanar grid. The pulse shapes of all event signals were read out by FADCs with a sampling rate of 100 MHz. The signals were reproduced by a detector simulation which hence was used to study the cuts for energies up to 3 MeV and different detector regions.