  The primary goal of the GERmanium Detector Array (Gerda) experiment at the
Laboratori Nazionali del Gran Sasso of INFN is the search for the neutrinoless
double beta decay of Ge-76. High-purity germanium detectors made from material
enriched in Ge-76 are operated directly immersed in liquid argon, allowing for
a substantial reduction of the background with respect to predecessor
experiments. The first 5.04 kg yr of data collected in Phase I of the
experiment have been analyzed to measure the half-life of the
neutrino-accompanied double beta decay of Ge-76. The observed spectrum in the
energy range between 600 and 1800 keV is dominated by the double beta decay of
Ge-76. The half-life extracted from Gerda data is T(1/2) = (1.84 +0.14 -0.10)
10^{21} yr.
