Dresden 2013 – wissenschaftliches Programm

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T: Fachverband Teilchenphysik

T 103: Niederenergie-Neutrinophysik 5

T 103.4: Vortrag

Donnerstag, 7. März 2013, 17:40–17:55, WIL-A317

Background characterization for the GERDA experiment — •Neslihan Becerici-Schmidt — Max-Planck-Institut für Physik, München

The GERmanium Detector Array (Gerda) experiment at the LNGS laboratory of INFN searches for the neutrinoless double beta (0νββ) decay of ⁷⁶Ge. A discovery of this decay can greatly advance our knowledge on the nature and properties of neutrinos. The current best limit on the half-life of ⁷⁶Ge 0νββ decay is 1.9·10²⁵ years (90% C.L.). In order to increase the sensitivity on the half-life with respect to past experiments, the background rate in the energy region of interest (ROI) around Q_ββ= 2039 keV has been reduced by a factor 10. Gerda started data-taking with the full set of Phase I detectors in November 2011. Identification of the background in the first phase of the experiment is of major importance to further mitigate the background for Gerda Phase II.

An analysis of the Phase I data resulted in a good understanding of the individual components in the Gerda background spectrum. The background components in the ROI have been identified to be mainly due to β- and γ-induced events originating from ²¹⁴Bi (²³⁸U-series), ²⁰⁸Tl (²³²Th-series), ⁴²K (progeny of ⁴²Ar) and α-induced events coming from isotopes in the ²²⁶Ra decay chain. A background decomposition in the ROI will be presented, with a special emphasis on the contribution from α-induced events.