Double beta decay of Ge-76 into excited states of Se-76 in GERDA

GERDA searches for the neutrinoless double beta (0νββ) decay of 76-Ge. The observation of such a decay would prove the Majorana character of the neutrino and indicate the effective Majorana neutrino mass.

The half life of the neutrino accompanied double beta (2νββ) decay of 76-Ge into the ground state of 76-Se was measured by GERDA with unprecedented precision. Furthermore 76-Ge can decay into excited states of 76-Se, although these transitions are phase space suppressed. Theoretical predictions for the half lives of these transitions vary by several orders of magnitude since they depend on various nuclear models. The observation of the 2νββ decay of 76-Ge into excited states would constrain these models and improve the models for the 0νββ decay, which rely on similar assumptions.

The poster will present the analysis and preliminary results of GERDA Phase II on 2νββ of 76-Ge into excited states.