Speaker
Description
The observation of neutrinoless double beta ($0\nu\beta\beta$) decay would prove lepton number violation and would shed light onto the nature of neutrinos. The GERDA experiment is aiming to perform a background free search for this process in $^{76}$Ge by operating isotopically enriched high purity Germanium detectors bare in liquid argon. Phase II of the experiment combines for the first time the excellent properties of semiconductor Germanium detectors with an active background suppression technique based on the simultaneous detection of liquid argon scintillation light by photomultiplier tubes and silicon photomultipliers coupled to scintillating fibers (LAr veto).
This talk outlines the Phase II upgrade with special emphasis on background rejection techniques and focusses on the first results of Phase II. Exhibiting the world-best background index (if normalized to the narrow energy-signal region of Germanium detectors), a limit on the $0\nu\beta\beta$-decay half-life of $^{76}$Ge of $5.3 \cdot 10^{25}$ yr at 90% C.L. could be set based on an exposure of only 34.4 kg$\cdot$yr. With an ultimate exposure of 100 kg$\cdot$yr this will allow for a $0\nu\beta\beta$-decay half-life sensitivity of the GERDA Phase II experiment of $10^{26}$ yr.
| Author's Name | Anne Christin Wegmann |
|---|---|
| Author's Institute | Max-Planck-Institut fuer Kernphysik |
| Author's e-mail | anne.wegmann@mpi-hd.mpg.de |
| Abstract Title | Background free search for neutrinoless double beta decay with GERDA Phase II |
| Subject | Neutrinos |
