Author/Authors :
L. Baudis، نويسنده , , M Günther، نويسنده , , H. Ferkel and R. J. Hellmig، نويسنده , , G Heusser، نويسنده , , M Hirsch، نويسنده , , H.V. Klapdor-Kleingrothaus، نويسنده , , H P?s، نويسنده , , Y. Ramachers and H. Strecker، نويسنده , , H Strecker، نويسنده , , M. J. Vollinger ، نويسنده , , A Bakalyarov، نويسنده , , A Balysh، نويسنده , , S.T Belyaev، نويسنده , , V.I Lebedev، نويسنده , , S Zhoukov، نويسنده , , S Kolb، نويسنده ,
Abstract :
The Heidelberg-Moscow experiment operates five enriched 76Ge detectors with 10.96 kg active mass in the Gran Sasso underground laboratory. After 28.7 kg y of measurement with a counting rate between 2000 keV and 2080 keV of 0.20 ± 0.01 cts/kg y keV we receive a lower limit on the neutrinoless double beta decay of 76Ge of T12(0+ → 0+) > 1.1 × 1025 y (90% C.L.). This restricts the Majorana neutrino mass to 0.46 eV. Recently we achieved a reduction in the background counting rate by a factor of 3–5 within the energy region of the neutrinoless double beta decay by recording the differentiated preamplifier pulse shapes and doing an off-line analysis to distinguish between pointlike and multiple scattered interactions.
