Heidelberg-Moscow ββ experiment with 76 Ge: Full setup with five detectors

摘要: The full setup of the Heidelberg-Moscow double \ensuremath{\beta} decay experiment is presented. This gives at present most stringent upper bound, improving neutrino mass limit into sub-eV range. Out 19.2 kg 86% ${\mathrm{enriched}}^{76}$Ge five crystals were grown with a total 11.51 kg. Since February 1995 all detectors, corresponding to 10.96 active mass, are in regular operation Gran Sasso underground laboratory, four them common shield. No signal observed for neutrinoless (0\ensuremath{\nu}\ensuremath{\beta}\ensuremath{\beta}). measured data from first three enriched detectors statistical significance 13.60 yr result new half-life ${\mathit{T}}_{1/2}$${(0}^{+}$\ensuremath{\rightarrow}${0}^{+}$)g7.4\ifmmode\times\else\texttimes\fi{}${10}^{24}$ (90% C.L.). With this Majorana neutrinos larger than 0.6 eV C.L.) excluded. From taken previously operated shielding and 10.58 results extracted two (2\ensuremath{\nu}\ensuremath{\beta}\ensuremath{\beta}) ${\mathrm{of}}^{76}$Ge. procedure quantitative model-independent description background via Monte Carlo simulation outlined some detail. combined ${\mathit{T}}_{1/2}^{2\mathrm{\ensuremath{\nu}}}$=[${1.77}_{\mathrm{\ensuremath{-}}0.01}^{+0.01}$${(\mathrm{stat})}_{\mathrm{\ensuremath{-}}0.11}^{+0.13}$(sys)]\ifmmode\times\else\texttimes\fi{}${10}^{21}$ yr. Further on concerning Majoron models impact SUSY parameters briefly reviewed. Future improvements application digital pulse shape analysis discussed an outlook future \ensuremath{\beta}\ensuremath{\beta} research given.