Flux Modulations seen by the Muon Veto of the GERDA Experiment

The GERDA experiment at LNGS of INFN is equipped with an active muon veto. The main part of the system is a water Cherenkov veto with 66~PMTs in the water tank surrounding the GERDA cryostat. The muon flux recorded by this veto shows a seasonal modulation. Two effects have been identified which are caused by secondary muons from the CNGS neutrino beam (2.2 %) and a temperature modulation of the atmosphere (1.4 %). A mean cosmic muon rate of $I^0_{\mu} = (3.477 \pm 0.002_{\textrm{stat}} \pm 0.067_{\textrm{sys}}) \times 10^{-4}$/(s$\cdot$m$^2$) was found in good agreement with other experiments at LNGS at a depth of 3500~meter water equivalent.Comment: 7 pages, 6 figure

Limit on Neutrinoless Double Beta Decay of 76Ge by GERDA

The Gerda experiment at the Laboratori Nazionali del Gran Sasso in Italy uses germanium detectors made from material with an enriched Ge-76 isotope fraction to search for neutrinoless double beta decay of this nucleus. Applying a blind analysis we find no signal after an exposure of 21.6 kg.yr and a background of about 0.01 cts/(keV.kg.yr). A half-life limit of T-1/20(v) > 2.1 . 10(25) yr (90% C.L.) is extracted. The previous claim of a signal for Ge-76 is excluded with 99% probability in a model independent way

Search of Neutrinoless Double Beta Decay with the GERDA Experiment

The GERDA (GERmanium Detector Array) is an experiment for the search of neutrinoless double beta decay (0 nu beta beta) in Ge-76, located at Laboratori Nazionali del Gran Sasso of INFN (Italy). In the first phase of the experiment, a 90% confidence level (C.L.) sensitivity of 2.4 . 10(25) yr on the 0 nu beta beta decay half-life was achieved with a 21.6 kg.yr exposure and an unprecedented background index in the region of interest of 10(-2) counts/(keV.kg.yr). No excess of signal events was found, and an experimental lower limit on the half-life of 2.1 . 10(25) yr (90% C.L.) was established. Correspondingly, the limit on the effective Majorana neutrino mass is m(ee) < 0.2-0.4 eV, depending on the considered nuclear matrix element. The previous claim for evidence of a 0 nu beta beta decay signal is strongly disfavored, and the field of research is open again

Damping signatures at JUNO, a medium-baseline reactor neutrino oscillation experiment

Abstract We study damping signatures at the Jiangmen Underground Neutrino Observatory (JUNO), a medium-baseline reactor neutrino oscillation experiment. These damping signatures are motivated by various new physics models, including quantum decoherence, nu(3) decay, neutrino absorption, and wave packet decoherence. The phenomenological effects of these models can be characterized by exponential damping factors at the probability level. We assess how well JUNO can constrain these damping parameters and how to disentangle these different damping signatures at JUNO. Compared to current experimental limits, JUNO can significantly improve the limits on tau(3)/m(3) in the nu(3) decay model, the width of the neutrino wave packet sigma(x), and the intrinsic relative dispersion of neutrino momentum sigma(rel)