Phase shift analysis and extraction of structure functions for Coulomb distortion on (e, e'p) reactions at high electron energies |
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Authors: | KS Kim Myung Ki Cheoun Yeungun Chung Hyung Joo Nam |
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Institution: | (1) Max-Planck-Institute für Kernphysik, Postfach 10 39 80, D-69029 Heidelberg, Germany, DE;(2) Russian Science Centre, Kurchatov Institute, 123 182 Moscow, Russia, RU |
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Abstract: | New results for the double beta decay of 76
Ge are presented. They are extracted from data obtained with the HEIDELBERG-MOSCOW experiment, which operates five enriched
76
Ge 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
2ν = 1.55±0.01(stat)+0.19
-0.15(syst)]×1021 y. The lower limit on the half-life of the 0νββ decay obtained with pulse shape analysis is T
1/2
0ν > 1.9×1025(3.1×1025) 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.
Received: 22 August 2001 / Accepted: 18 October 2001 |
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Keywords: | PACS 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 |
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