Münster 2017 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 14: Astroparticle Physics I

HK 14.3: Talk

Tuesday, March 28, 2017, 11:45–12:00, F 33

Pulse shape discrimination performance of BEGe detectors in Gerda Phase II — •Anna Julia Zsigmond for the GERDA collaboration — Max Planck Institut für Physik, München

The Gerda experiment searches for the lepton number violating neutrinoless double beta (0νββ) decay of ⁷⁶Ge. Bare Ge diodes are operated in liquid argon at cryogenic temperatures in an ultra-low background environment. Isotopically enriched Broad Energy Germanium (BEGe) detectors are used in Phase II of the experiment because of their superior energy resolution and pulse shape discrimination properties. 0νββ events are single-site events confined in the detector active volume to a scale of about a millimeter, while most of the backgrounds are multi-site gamma-ray events or surface events. These events are identified by a single parameter, the amplitude of the change pulse over the energy of the event and rejected to maximize the sensitivity of the experiment. The long-term stability and performance of the detectors during Phase II data taking using calibration and 2νββ data will be presented. The effect of pulse shape discrimination on the background index and 0νββ half-life limit will be demonstrated.