Background-free search for neutrino-less double beta decay of 76Ge with GERDA

The GERDA detector, installed in the underground laboratory at Gran Sasso (LNGS) in Italy has been designed to search for neutrino-less double beta (0vββ) decay of 76Ge. Observation of this process would mean that neutrino is a Majorana particle and the lepton number is not conserved, implying physics beyond the Standard Model.

 

In GERDA high-purity Germanium (HPGe) detectors enriched in the 76Ge isotope are used. They are directly immersed in the radio-pure liquid argon, which acts as a passive/active shield and as a cooling medium for the detectors. Recently a new half-life limit on the 0vββ decay of 76Ge of T1/2 > 1x10^26 yr has been obtained. The background rate in the energy region of interest is so low that < 1 count is expected within the anticipated life time of the experiment. Thus, GERDA is the first background-free detector devoted to searches for the 0vββ decay with high discovery potential. The design, the importance of the achieved results, and the perspectives of GERDA will be discussed.