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T: Fachverband Teilchenphysik
T 109: Niederenergie-Neutrinophysik/Suche nach Dunkler Materie 4
T 109.1: Group Report
Tuesday, February 28, 2012, 16:45–17:05, ZHG 103
The Gerda experiment on 0νββ decay — •Kai Freund — Eberhard Karls Universität Tübingen, Germany
The Gerda (Germanium Detector Array) collaboration searches for the neutrinoless double beta decay (0νββ) of 76Ge. The existence of this decay would give rise to the assumption that the neutrino is a Majorana particle, i.e. its own antiparticle. A measured half-life could be used to determine the effective neutrino mass and hence resolve the neutrino mass hierarchy problem. Germanium diodes, isotopically enriched in 76Ge, are used as both source and detector. Due to the low rate of this decay (T1/2>1025 y), the experimental background must be reduced to a level of 10−2counts/(kg y keV) or better in the region around Qββ. To minimize background from cosmogenically produced secondary particles, a low Z shielding is employed. Thus, the naked diodes are operated in a liquid argon cryostat, which is surrounded by a water tank acting as both passive shield and active muon Cherenkov veto.
Gerda started the commissioning runs in 2010 and in November 2011, the first phase of data taking with enriched detectors has begun. In this talk, the first year of the experiment will be summarized.
[1] GERDA proposal 2004, htpp://www.mpi-hd.mpg.de/gerda
This work was supported by BMBF (05A08VT1).