Eur. Phys. J. A 12, 147-154 (2001)
Latest results from the HEIDELBERG-MOSCOW double beta decay experiment
H.V. Klapdor-Kleingrothaus1, A. Dietz1, L. Baudis1, G. Heusser1, I.V. Krivosheina1, B. Majorovits1, H. Paes1, H. Strecker1, V. Alexeev2, A. Balysh2, A. Bakalyarov2, S.T. Belyaev2, V.I. Lebedev2 and S. Zhukov21 Max-Planck-Institute für Kernphysik, Postfach 10 39 80, D-69029 Heidelberg, Germany
2 Russian Science Centre, Kurchatov Institute, 123 182 Moscow, Russia
klapdor@gustav.mpi-hd.mpg.de
(Received: 22 August 2001 Communicated by D. Schwalm)
Abstract
New results for the double beta decay of 76Ge are presented.
They are extracted from data obtained with the HEIDELBERG-MOSCOW experiment, which operates
five enriched 76Ge detectors in an extreme low-level
environment in the Gran Sasso underground laboratory.
The two-neutrino-accompanied double beta decay is evaluated for the
first time for all five detectors with a statistical significance of
47.7 kg y resulting in a half-life of
![$T_{1/2}^{2\nu}=[1.55\pm0.01({\rm stat)} ^{+0.19}_{-0.15}({\rm syst})]\times
10^{21}$](/articles/epja/abs/2001/10/100500147/img1.gif){kind=small}
y.
The lower limit on the half-life of the
decay obtained with
pulse shape analysis is
) y with 90%
C.L. (68% C.L.) (with 35.5 kg y).
This results in an upper limit of the effective Majorana-neutrino mass
of 0.35 eV (0.27 eV) using the matrix elements
of A. Staudt et al.'s work (Europhys. Lett. 13, 31 (1990)).
This is the most stringent limit at present from double beta decay.
No evidence for a majoron-emitting decay mode
is observed.
14.60.Pq - Neutrino mass and mixing.
23.40.Bw - Weak-interaction and lepton (including neutrino) aspects.
23.40.-s - Beta decay; double beta decay; electron and muon capture.
12.60.Jv - Supersymmetric models.
© Società Italiana di Fisica, Springer-Verlag 2001
