Searching for double-beta decays with the GERDA experiment

The search for neutrinoless double-beta decay (0νββ) is presently the only feasible way to approach the fundamental question regarding the Majorana or Dirac nature of the neutrino. The observation of 0νββ would be the proof that the neutrino is a Majorana particle, i.e. that it is its own antiparticle. The measurement of the half-life of 0νββ would give direct access to a determination of the effective Majorana mass of the neutrino. The Germanium Detector Array (GERDA) experiment at the LNGS underground laboratories uses high-purity germanium detectors to search for 0νββ of 76Ge. The experiment started Phase I in November 2011, using 15 kg of enriched germanium crystals with the goal of a background index of 10-2 counts/(keV.kg.y). A second, later phase will double the mass of the enriched detectors and aim at a background at the level of 10-3 counts/(keV.kg.y). This contribution presents the status of the GERDA Phase I data taking. A short outlook is given on the ongoing preparations for Phase II.