Heidelberg-Moscow {beta}{beta} experiment with {sup 76}Ge: Full setup with five detectors

Journal Article · Wed Jan 01 04:00:00 EST 1997 · Physical Review, D

DOI:https://doi.org/10.1103/PhysRevD.55.54· OSTI ID:439115

Guenther, M; Hellmig, J; Heusser, G; Hirsch, M; Klapdor-Kleingrothaus, H V; Maier, B; Paes, H; Petry, F; Ramachers, Y; Strecker, H; Voellinger, M ^[1]; Balysh, A; Belyaev, S T; Demehin, A; Gurov, A; Kondratenko, I; Kotelnikov, D; Lebedev, V I ^[2]; Mueller, A ^[3]

---

1. Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany)
2. Russian Science Center Kurchatov Institute, 123 182 Moscow (Russia)
3. Istituto Nazionale di Fisica Nucleare, I-67010 Assergi (Italy)

The full setup of the Heidelberg-Moscow double {beta} decay experiment is presented. This experiment gives at present the most stringent upper bound, improving the neutrino mass limit into the sub-eV range. Out of 19.2 kg of 86{percent} enriched {sup 76}Ge five crystals were grown with a total mass of 11.51 kg. Since February 1995 all five detectors, corresponding to 10.96 kg active mass, are in regular operation in the Gran Sasso underground laboratory, four of them in a common shield. No signal is observed for the neutrinoless double {beta} decay (0{nu}{beta}{beta}). The measured data from the first three enriched detectors with a statistical significance of 13.60 kgyr result in a new half-life limit of T{sub 1/2}(0{sup +}{r_arrow}0{sup +}){gt}7.4{times}10{sup 24} yr (90{percent} C.L.). With this limit a Majorana mass of the neutrinos larger than 0.6 eV (90{percent} C.L.) is excluded. From the data taken in the previously operated setup with three enriched detectors in a common shielding and a statistical significance of 10.58 kgyr new results are extracted for the two neutrino double {beta} decay (2{nu}{beta}{beta}) of {sup 76}Ge. The procedure of a quantitative and model-independent description of the background via a Monte Carlo simulation is outlined in some detail. The combined result is T{sub 1/2}{sup 2{nu}}=[1.77{sub {minus}0.01}{sup +0.01}(stat){sub {minus}0.11}{sup +0.13}(sys)]{times}10{sup 21} yr. Further on the results concerning new Majoron models and the impact on SUSY parameters are briefly reviewed. Future improvements on the background with the application of digital pulse shape analysis are discussed and an outlook on the future of {beta}{beta} research is given. {copyright} {ital 1996} {ital The American Physical Society}

• OSTI ID: 439115
• Journal Information: Physical Review, D, Journal Name: Physical Review, D Journal Issue: 1 Vol. 55; ISSN PRVDAQ; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
DOUBLE BETA DECAY
GERMANIUM 76
HALF-LIFE
MASS
MONTE CARLO METHOD
NEUTRINOS