Search for neutrinoless double beta decay with enriched 76Ge in Gran Sasso 1990-2003

Klapdor-Kleingrothaus, H. V.; Krivosheina, I. V.; Dietz, A.; Chkvorets, O.

Search for neutrinoless double beta decay with enriched 76Ge in Gran Sasso 1990-2003

Authors

Klapdor-Kleingrothaus, H. V.

Krivosheina, I. V.

Dietz, A.

Chkvorets, O.

Description

The results of the HEIDELBERG-MOSCOW experiment which searches with 11 kg of enriched 76Ge for double beta decay in the GRAN Sasso underground laboratory are presented for the full running period August 1990 - May 2003. The duty cycle of the experiment was ~80%, the collected statistics is 71.7 kg y. The background achieved in the energy region of the Q value for double beta decay is 0.11 events/ kg y keV. The two-neutrino accompanied half-life is determined on the basis of more than 100 000 events. The confidence level for the neutrinoless signal has been improved to 4.2 sigma.
19 pages, latex, 9 figures, 2 tables